Disney BSSRDF, sample scattering profile, lower

Percentage Accurate: 61.1% → 97.7%
Time: 7.7s
Alternatives: 7
Speedup: 11.4×

Specification

?
\[\left(0 \leq s \land s \leq 256\right) \land \left(2.328306437 \cdot 10^{-10} \leq u \land u \leq 0.25\right)\]
\[\begin{array}{l} \\ s \cdot \log \left(\frac{1}{1 - 4 \cdot u}\right) \end{array} \]
(FPCore (s u) :precision binary32 (* s (log (/ 1.0 (- 1.0 (* 4.0 u))))))
float code(float s, float u) {
	return s * logf((1.0f / (1.0f - (4.0f * u))));
}
real(4) function code(s, u)
    real(4), intent (in) :: s
    real(4), intent (in) :: u
    code = s * log((1.0e0 / (1.0e0 - (4.0e0 * u))))
end function
function code(s, u)
	return Float32(s * log(Float32(Float32(1.0) / Float32(Float32(1.0) - Float32(Float32(4.0) * u)))))
end
function tmp = code(s, u)
	tmp = s * log((single(1.0) / (single(1.0) - (single(4.0) * u))));
end
\begin{array}{l}

\\
s \cdot \log \left(\frac{1}{1 - 4 \cdot u}\right)
\end{array}

Sampling outcomes in binary32 precision:

Local Percentage Accuracy vs ?

The average percentage accuracy by input value. Horizontal axis shows value of an input variable; the variable is choosen in the title. Vertical axis is accuracy; higher is better. Red represent the original program, while blue represents Herbie's suggestion. These can be toggled with buttons below the plot. The line is an average while dots represent individual samples.

Accuracy vs Speed?

Herbie found 7 alternatives:

AlternativeAccuracySpeedup
The accuracy (vertical axis) and speed (horizontal axis) of each alternatives. Up and to the right is better. The red square shows the initial program, and each blue circle shows an alternative.The line shows the best available speed-accuracy tradeoffs.

Initial Program: 61.1% accurate, 1.0× speedup?

\[\begin{array}{l} \\ s \cdot \log \left(\frac{1}{1 - 4 \cdot u}\right) \end{array} \]
(FPCore (s u) :precision binary32 (* s (log (/ 1.0 (- 1.0 (* 4.0 u))))))
float code(float s, float u) {
	return s * logf((1.0f / (1.0f - (4.0f * u))));
}
real(4) function code(s, u)
    real(4), intent (in) :: s
    real(4), intent (in) :: u
    code = s * log((1.0e0 / (1.0e0 - (4.0e0 * u))))
end function
function code(s, u)
	return Float32(s * log(Float32(Float32(1.0) / Float32(Float32(1.0) - Float32(Float32(4.0) * u)))))
end
function tmp = code(s, u)
	tmp = s * log((single(1.0) / (single(1.0) - (single(4.0) * u))));
end
\begin{array}{l}

\\
s \cdot \log \left(\frac{1}{1 - 4 \cdot u}\right)
\end{array}

Alternative 1: 97.7% accurate, 0.9× speedup?

\[\begin{array}{l} \\ \begin{array}{l} t_0 := 1 - u \cdot 4\\ \mathbf{if}\;t\_0 \leq 0.9800000190734863:\\ \;\;\;\;\log \left(\frac{1}{t\_0}\right) \cdot s\\ \mathbf{else}:\\ \;\;\;\;\left(\left(\left(\frac{\frac{4}{u} + 8}{u} \cdot u - -21.333333333333332 \cdot u\right) \cdot u\right) \cdot s\right) \cdot u\\ \end{array} \end{array} \]
(FPCore (s u)
 :precision binary32
 (let* ((t_0 (- 1.0 (* u 4.0))))
   (if (<= t_0 0.9800000190734863)
     (* (log (/ 1.0 t_0)) s)
     (*
      (* (* (- (* (/ (+ (/ 4.0 u) 8.0) u) u) (* -21.333333333333332 u)) u) s)
      u))))
float code(float s, float u) {
	float t_0 = 1.0f - (u * 4.0f);
	float tmp;
	if (t_0 <= 0.9800000190734863f) {
		tmp = logf((1.0f / t_0)) * s;
	} else {
		tmp = (((((((4.0f / u) + 8.0f) / u) * u) - (-21.333333333333332f * u)) * u) * s) * u;
	}
	return tmp;
}
real(4) function code(s, u)
    real(4), intent (in) :: s
    real(4), intent (in) :: u
    real(4) :: t_0
    real(4) :: tmp
    t_0 = 1.0e0 - (u * 4.0e0)
    if (t_0 <= 0.9800000190734863e0) then
        tmp = log((1.0e0 / t_0)) * s
    else
        tmp = (((((((4.0e0 / u) + 8.0e0) / u) * u) - ((-21.333333333333332e0) * u)) * u) * s) * u
    end if
    code = tmp
end function
function code(s, u)
	t_0 = Float32(Float32(1.0) - Float32(u * Float32(4.0)))
	tmp = Float32(0.0)
	if (t_0 <= Float32(0.9800000190734863))
		tmp = Float32(log(Float32(Float32(1.0) / t_0)) * s);
	else
		tmp = Float32(Float32(Float32(Float32(Float32(Float32(Float32(Float32(Float32(4.0) / u) + Float32(8.0)) / u) * u) - Float32(Float32(-21.333333333333332) * u)) * u) * s) * u);
	end
	return tmp
end
function tmp_2 = code(s, u)
	t_0 = single(1.0) - (u * single(4.0));
	tmp = single(0.0);
	if (t_0 <= single(0.9800000190734863))
		tmp = log((single(1.0) / t_0)) * s;
	else
		tmp = (((((((single(4.0) / u) + single(8.0)) / u) * u) - (single(-21.333333333333332) * u)) * u) * s) * u;
	end
	tmp_2 = tmp;
end
\begin{array}{l}

\\
\begin{array}{l}
t_0 := 1 - u \cdot 4\\
\mathbf{if}\;t\_0 \leq 0.9800000190734863:\\
\;\;\;\;\log \left(\frac{1}{t\_0}\right) \cdot s\\

\mathbf{else}:\\
\;\;\;\;\left(\left(\left(\frac{\frac{4}{u} + 8}{u} \cdot u - -21.333333333333332 \cdot u\right) \cdot u\right) \cdot s\right) \cdot u\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (-.f32 #s(literal 1 binary32) (*.f32 #s(literal 4 binary32) u)) < 0.980000019

    1. Initial program 95.2%

      \[s \cdot \log \left(\frac{1}{1 - 4 \cdot u}\right) \]
    2. Add Preprocessing

    if 0.980000019 < (-.f32 #s(literal 1 binary32) (*.f32 #s(literal 4 binary32) u))

    1. Initial program 53.1%

      \[s \cdot \log \left(\frac{1}{1 - 4 \cdot u}\right) \]
    2. Add Preprocessing
    3. Taylor expanded in u around 0

      \[\leadsto \color{blue}{u \cdot \left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right)} \]
    4. Step-by-step derivation
      1. *-commutativeN/A

        \[\leadsto \color{blue}{\left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u} \]
      2. lower-*.f32N/A

        \[\leadsto \color{blue}{\left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u} \]
      3. *-commutativeN/A

        \[\leadsto \left(\color{blue}{s \cdot 4} + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u \]
      4. distribute-rgt-inN/A

        \[\leadsto \left(s \cdot 4 + \color{blue}{\left(\left(8 \cdot s\right) \cdot u + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)}\right) \cdot u \]
      5. associate-*r*N/A

        \[\leadsto \left(s \cdot 4 + \left(\color{blue}{8 \cdot \left(s \cdot u\right)} + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)\right) \cdot u \]
      6. *-commutativeN/A

        \[\leadsto \left(s \cdot 4 + \left(\color{blue}{\left(s \cdot u\right) \cdot 8} + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)\right) \cdot u \]
      7. *-commutativeN/A

        \[\leadsto \left(s \cdot 4 + \left(\left(s \cdot u\right) \cdot 8 + \color{blue}{\left(\left(s \cdot u\right) \cdot \frac{64}{3}\right)} \cdot u\right)\right) \cdot u \]
      8. associate-*l*N/A

        \[\leadsto \left(s \cdot 4 + \left(\left(s \cdot u\right) \cdot 8 + \color{blue}{\left(s \cdot u\right) \cdot \left(\frac{64}{3} \cdot u\right)}\right)\right) \cdot u \]
      9. distribute-lft-outN/A

        \[\leadsto \left(s \cdot 4 + \color{blue}{\left(s \cdot u\right) \cdot \left(8 + \frac{64}{3} \cdot u\right)}\right) \cdot u \]
      10. associate-*l*N/A

        \[\leadsto \left(s \cdot 4 + \color{blue}{s \cdot \left(u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)}\right) \cdot u \]
      11. distribute-lft-inN/A

        \[\leadsto \color{blue}{\left(s \cdot \left(4 + u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)\right)} \cdot u \]
      12. lower-*.f32N/A

        \[\leadsto \color{blue}{\left(s \cdot \left(4 + u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)\right)} \cdot u \]
      13. +-commutativeN/A

        \[\leadsto \left(s \cdot \color{blue}{\left(u \cdot \left(8 + \frac{64}{3} \cdot u\right) + 4\right)}\right) \cdot u \]
      14. *-commutativeN/A

        \[\leadsto \left(s \cdot \left(\color{blue}{\left(8 + \frac{64}{3} \cdot u\right) \cdot u} + 4\right)\right) \cdot u \]
      15. lower-fma.f32N/A

        \[\leadsto \left(s \cdot \color{blue}{\mathsf{fma}\left(8 + \frac{64}{3} \cdot u, u, 4\right)}\right) \cdot u \]
      16. +-commutativeN/A

        \[\leadsto \left(s \cdot \mathsf{fma}\left(\color{blue}{\frac{64}{3} \cdot u + 8}, u, 4\right)\right) \cdot u \]
      17. lower-fma.f3281.9

        \[\leadsto \left(s \cdot \mathsf{fma}\left(\color{blue}{\mathsf{fma}\left(21.333333333333332, u, 8\right)}, u, 4\right)\right) \cdot u \]
    5. Applied rewrites81.9%

      \[\leadsto \color{blue}{\left(s \cdot \mathsf{fma}\left(\mathsf{fma}\left(21.333333333333332, u, 8\right), u, 4\right)\right) \cdot u} \]
    6. Taylor expanded in u around inf

      \[\leadsto \left(s \cdot \left({u}^{2} \cdot \left(\frac{64}{3} + \left(8 \cdot \frac{1}{u} + \frac{4}{{u}^{2}}\right)\right)\right)\right) \cdot u \]
    7. Step-by-step derivation
      1. Applied rewrites98.2%

        \[\leadsto \left(s \cdot \left(\left(\left(\left(21.333333333333332 + \frac{4}{u \cdot u}\right) + \frac{8}{u}\right) \cdot u\right) \cdot u\right)\right) \cdot u \]
      2. Taylor expanded in u around -inf

        \[\leadsto \left(s \cdot \left(\left(-1 \cdot \left(u \cdot \left(-1 \cdot \frac{8 + 4 \cdot \frac{1}{u}}{u} - \frac{64}{3}\right)\right)\right) \cdot u\right)\right) \cdot u \]
      3. Step-by-step derivation
        1. Applied rewrites98.4%

          \[\leadsto \left(s \cdot \left(\left(\left(-u\right) \cdot \left(-21.333333333333332 - \frac{\frac{4}{u} + 8}{u}\right)\right) \cdot u\right)\right) \cdot u \]
        2. Step-by-step derivation
          1. Applied rewrites98.5%

            \[\leadsto \left(s \cdot \left(\left(\left(-u\right) \cdot -21.333333333333332 + \left(-u\right) \cdot \frac{-\left(8 + \frac{4}{u}\right)}{u}\right) \cdot u\right)\right) \cdot u \]
        3. Recombined 2 regimes into one program.
        4. Final simplification97.8%

          \[\leadsto \begin{array}{l} \mathbf{if}\;1 - u \cdot 4 \leq 0.9800000190734863:\\ \;\;\;\;\log \left(\frac{1}{1 - u \cdot 4}\right) \cdot s\\ \mathbf{else}:\\ \;\;\;\;\left(\left(\left(\frac{\frac{4}{u} + 8}{u} \cdot u - -21.333333333333332 \cdot u\right) \cdot u\right) \cdot s\right) \cdot u\\ \end{array} \]
        5. Add Preprocessing

        Alternative 2: 61.1% accurate, 2.0× speedup?

        \[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;1 - u \cdot 4 \leq 0.9999899864196777:\\ \;\;\;\;\left(\frac{u}{\mathsf{fma}\left(21.333333333333332, u, -8\right)} \cdot \mathsf{fma}\left(u \cdot u, 455.1111111111111, -64\right) - -4\right) \cdot \left(s \cdot u\right)\\ \mathbf{else}:\\ \;\;\;\;\left(u \cdot 4\right) \cdot s\\ \end{array} \end{array} \]
        (FPCore (s u)
         :precision binary32
         (if (<= (- 1.0 (* u 4.0)) 0.9999899864196777)
           (*
            (-
             (*
              (/ u (fma 21.333333333333332 u -8.0))
              (fma (* u u) 455.1111111111111 -64.0))
             -4.0)
            (* s u))
           (* (* u 4.0) s)))
        float code(float s, float u) {
        	float tmp;
        	if ((1.0f - (u * 4.0f)) <= 0.9999899864196777f) {
        		tmp = (((u / fmaf(21.333333333333332f, u, -8.0f)) * fmaf((u * u), 455.1111111111111f, -64.0f)) - -4.0f) * (s * u);
        	} else {
        		tmp = (u * 4.0f) * s;
        	}
        	return tmp;
        }
        
        function code(s, u)
        	tmp = Float32(0.0)
        	if (Float32(Float32(1.0) - Float32(u * Float32(4.0))) <= Float32(0.9999899864196777))
        		tmp = Float32(Float32(Float32(Float32(u / fma(Float32(21.333333333333332), u, Float32(-8.0))) * fma(Float32(u * u), Float32(455.1111111111111), Float32(-64.0))) - Float32(-4.0)) * Float32(s * u));
        	else
        		tmp = Float32(Float32(u * Float32(4.0)) * s);
        	end
        	return tmp
        end
        
        \begin{array}{l}
        
        \\
        \begin{array}{l}
        \mathbf{if}\;1 - u \cdot 4 \leq 0.9999899864196777:\\
        \;\;\;\;\left(\frac{u}{\mathsf{fma}\left(21.333333333333332, u, -8\right)} \cdot \mathsf{fma}\left(u \cdot u, 455.1111111111111, -64\right) - -4\right) \cdot \left(s \cdot u\right)\\
        
        \mathbf{else}:\\
        \;\;\;\;\left(u \cdot 4\right) \cdot s\\
        
        
        \end{array}
        \end{array}
        
        Derivation
        1. Split input into 2 regimes
        2. if (-.f32 #s(literal 1 binary32) (*.f32 #s(literal 4 binary32) u)) < 0.999989986

          1. Initial program 79.9%

            \[s \cdot \log \left(\frac{1}{1 - 4 \cdot u}\right) \]
          2. Add Preprocessing
          3. Taylor expanded in u around 0

            \[\leadsto \color{blue}{u \cdot \left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right)} \]
          4. Step-by-step derivation
            1. *-commutativeN/A

              \[\leadsto \color{blue}{\left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u} \]
            2. lower-*.f32N/A

              \[\leadsto \color{blue}{\left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u} \]
            3. *-commutativeN/A

              \[\leadsto \left(\color{blue}{s \cdot 4} + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u \]
            4. distribute-rgt-inN/A

              \[\leadsto \left(s \cdot 4 + \color{blue}{\left(\left(8 \cdot s\right) \cdot u + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)}\right) \cdot u \]
            5. associate-*r*N/A

              \[\leadsto \left(s \cdot 4 + \left(\color{blue}{8 \cdot \left(s \cdot u\right)} + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)\right) \cdot u \]
            6. *-commutativeN/A

              \[\leadsto \left(s \cdot 4 + \left(\color{blue}{\left(s \cdot u\right) \cdot 8} + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)\right) \cdot u \]
            7. *-commutativeN/A

              \[\leadsto \left(s \cdot 4 + \left(\left(s \cdot u\right) \cdot 8 + \color{blue}{\left(\left(s \cdot u\right) \cdot \frac{64}{3}\right)} \cdot u\right)\right) \cdot u \]
            8. associate-*l*N/A

              \[\leadsto \left(s \cdot 4 + \left(\left(s \cdot u\right) \cdot 8 + \color{blue}{\left(s \cdot u\right) \cdot \left(\frac{64}{3} \cdot u\right)}\right)\right) \cdot u \]
            9. distribute-lft-outN/A

              \[\leadsto \left(s \cdot 4 + \color{blue}{\left(s \cdot u\right) \cdot \left(8 + \frac{64}{3} \cdot u\right)}\right) \cdot u \]
            10. associate-*l*N/A

              \[\leadsto \left(s \cdot 4 + \color{blue}{s \cdot \left(u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)}\right) \cdot u \]
            11. distribute-lft-inN/A

              \[\leadsto \color{blue}{\left(s \cdot \left(4 + u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)\right)} \cdot u \]
            12. lower-*.f32N/A

              \[\leadsto \color{blue}{\left(s \cdot \left(4 + u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)\right)} \cdot u \]
            13. +-commutativeN/A

              \[\leadsto \left(s \cdot \color{blue}{\left(u \cdot \left(8 + \frac{64}{3} \cdot u\right) + 4\right)}\right) \cdot u \]
            14. *-commutativeN/A

              \[\leadsto \left(s \cdot \left(\color{blue}{\left(8 + \frac{64}{3} \cdot u\right) \cdot u} + 4\right)\right) \cdot u \]
            15. lower-fma.f32N/A

              \[\leadsto \left(s \cdot \color{blue}{\mathsf{fma}\left(8 + \frac{64}{3} \cdot u, u, 4\right)}\right) \cdot u \]
            16. +-commutativeN/A

              \[\leadsto \left(s \cdot \mathsf{fma}\left(\color{blue}{\frac{64}{3} \cdot u + 8}, u, 4\right)\right) \cdot u \]
            17. lower-fma.f3255.5

              \[\leadsto \left(s \cdot \mathsf{fma}\left(\color{blue}{\mathsf{fma}\left(21.333333333333332, u, 8\right)}, u, 4\right)\right) \cdot u \]
          5. Applied rewrites55.5%

            \[\leadsto \color{blue}{\left(s \cdot \mathsf{fma}\left(\mathsf{fma}\left(21.333333333333332, u, 8\right), u, 4\right)\right) \cdot u} \]
          6. Step-by-step derivation
            1. Applied rewrites55.5%

              \[\leadsto \mathsf{fma}\left(s, \mathsf{fma}\left(21.333333333333332, u, 8\right) \cdot u, 4 \cdot s\right) \cdot u \]
            2. Step-by-step derivation
              1. Applied rewrites55.5%

                \[\leadsto \mathsf{fma}\left(s, \frac{\mathsf{fma}\left(455.1111111111111, u \cdot u, -64\right)}{\mathsf{fma}\left(21.333333333333332, u, -8\right)} \cdot u, 4 \cdot s\right) \cdot u \]
              2. Taylor expanded in s around -inf

                \[\leadsto -1 \cdot \color{blue}{\left(s \cdot \left(u \cdot \left(-1 \cdot \frac{u \cdot \left(\frac{4096}{9} \cdot {u}^{2} - 64\right)}{\frac{64}{3} \cdot u - 8} - 4\right)\right)\right)} \]
              3. Step-by-step derivation
                1. Applied rewrites75.4%

                  \[\leadsto \left(\left(-u\right) \cdot s\right) \cdot \color{blue}{\left(-4 - \mathsf{fma}\left(u \cdot u, 455.1111111111111, -64\right) \cdot \frac{u}{\mathsf{fma}\left(21.333333333333332, u, -8\right)}\right)} \]

                if 0.999989986 < (-.f32 #s(literal 1 binary32) (*.f32 #s(literal 4 binary32) u))

                1. Initial program 38.3%

                  \[s \cdot \log \left(\frac{1}{1 - 4 \cdot u}\right) \]
                2. Add Preprocessing
                3. Taylor expanded in u around 0

                  \[\leadsto s \cdot \color{blue}{\left(4 \cdot u\right)} \]
                4. Step-by-step derivation
                  1. *-commutativeN/A

                    \[\leadsto s \cdot \color{blue}{\left(u \cdot 4\right)} \]
                  2. lower-*.f3295.1

                    \[\leadsto s \cdot \color{blue}{\left(u \cdot 4\right)} \]
                5. Applied rewrites95.1%

                  \[\leadsto s \cdot \color{blue}{\left(u \cdot 4\right)} \]
              4. Recombined 2 regimes into one program.
              5. Final simplification84.3%

                \[\leadsto \begin{array}{l} \mathbf{if}\;1 - u \cdot 4 \leq 0.9999899864196777:\\ \;\;\;\;\left(\frac{u}{\mathsf{fma}\left(21.333333333333332, u, -8\right)} \cdot \mathsf{fma}\left(u \cdot u, 455.1111111111111, -64\right) - -4\right) \cdot \left(s \cdot u\right)\\ \mathbf{else}:\\ \;\;\;\;\left(u \cdot 4\right) \cdot s\\ \end{array} \]
              6. Add Preprocessing

              Alternative 3: 90.8% accurate, 2.3× speedup?

              \[\begin{array}{l} \\ \left(\left(\left(\frac{\frac{4}{u} + 8}{u} \cdot u - -21.333333333333332 \cdot u\right) \cdot u\right) \cdot s\right) \cdot u \end{array} \]
              (FPCore (s u)
               :precision binary32
               (* (* (* (- (* (/ (+ (/ 4.0 u) 8.0) u) u) (* -21.333333333333332 u)) u) s) u))
              float code(float s, float u) {
              	return (((((((4.0f / u) + 8.0f) / u) * u) - (-21.333333333333332f * u)) * u) * s) * u;
              }
              
              real(4) function code(s, u)
                  real(4), intent (in) :: s
                  real(4), intent (in) :: u
                  code = (((((((4.0e0 / u) + 8.0e0) / u) * u) - ((-21.333333333333332e0) * u)) * u) * s) * u
              end function
              
              function code(s, u)
              	return Float32(Float32(Float32(Float32(Float32(Float32(Float32(Float32(Float32(4.0) / u) + Float32(8.0)) / u) * u) - Float32(Float32(-21.333333333333332) * u)) * u) * s) * u)
              end
              
              function tmp = code(s, u)
              	tmp = (((((((single(4.0) / u) + single(8.0)) / u) * u) - (single(-21.333333333333332) * u)) * u) * s) * u;
              end
              
              \begin{array}{l}
              
              \\
              \left(\left(\left(\frac{\frac{4}{u} + 8}{u} \cdot u - -21.333333333333332 \cdot u\right) \cdot u\right) \cdot s\right) \cdot u
              \end{array}
              
              Derivation
              1. Initial program 61.5%

                \[s \cdot \log \left(\frac{1}{1 - 4 \cdot u}\right) \]
              2. Add Preprocessing
              3. Taylor expanded in u around 0

                \[\leadsto \color{blue}{u \cdot \left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right)} \]
              4. Step-by-step derivation
                1. *-commutativeN/A

                  \[\leadsto \color{blue}{\left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u} \]
                2. lower-*.f32N/A

                  \[\leadsto \color{blue}{\left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u} \]
                3. *-commutativeN/A

                  \[\leadsto \left(\color{blue}{s \cdot 4} + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u \]
                4. distribute-rgt-inN/A

                  \[\leadsto \left(s \cdot 4 + \color{blue}{\left(\left(8 \cdot s\right) \cdot u + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)}\right) \cdot u \]
                5. associate-*r*N/A

                  \[\leadsto \left(s \cdot 4 + \left(\color{blue}{8 \cdot \left(s \cdot u\right)} + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)\right) \cdot u \]
                6. *-commutativeN/A

                  \[\leadsto \left(s \cdot 4 + \left(\color{blue}{\left(s \cdot u\right) \cdot 8} + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)\right) \cdot u \]
                7. *-commutativeN/A

                  \[\leadsto \left(s \cdot 4 + \left(\left(s \cdot u\right) \cdot 8 + \color{blue}{\left(\left(s \cdot u\right) \cdot \frac{64}{3}\right)} \cdot u\right)\right) \cdot u \]
                8. associate-*l*N/A

                  \[\leadsto \left(s \cdot 4 + \left(\left(s \cdot u\right) \cdot 8 + \color{blue}{\left(s \cdot u\right) \cdot \left(\frac{64}{3} \cdot u\right)}\right)\right) \cdot u \]
                9. distribute-lft-outN/A

                  \[\leadsto \left(s \cdot 4 + \color{blue}{\left(s \cdot u\right) \cdot \left(8 + \frac{64}{3} \cdot u\right)}\right) \cdot u \]
                10. associate-*l*N/A

                  \[\leadsto \left(s \cdot 4 + \color{blue}{s \cdot \left(u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)}\right) \cdot u \]
                11. distribute-lft-inN/A

                  \[\leadsto \color{blue}{\left(s \cdot \left(4 + u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)\right)} \cdot u \]
                12. lower-*.f32N/A

                  \[\leadsto \color{blue}{\left(s \cdot \left(4 + u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)\right)} \cdot u \]
                13. +-commutativeN/A

                  \[\leadsto \left(s \cdot \color{blue}{\left(u \cdot \left(8 + \frac{64}{3} \cdot u\right) + 4\right)}\right) \cdot u \]
                14. *-commutativeN/A

                  \[\leadsto \left(s \cdot \left(\color{blue}{\left(8 + \frac{64}{3} \cdot u\right) \cdot u} + 4\right)\right) \cdot u \]
                15. lower-fma.f32N/A

                  \[\leadsto \left(s \cdot \color{blue}{\mathsf{fma}\left(8 + \frac{64}{3} \cdot u, u, 4\right)}\right) \cdot u \]
                16. +-commutativeN/A

                  \[\leadsto \left(s \cdot \mathsf{fma}\left(\color{blue}{\frac{64}{3} \cdot u + 8}, u, 4\right)\right) \cdot u \]
                17. lower-fma.f3273.0

                  \[\leadsto \left(s \cdot \mathsf{fma}\left(\color{blue}{\mathsf{fma}\left(21.333333333333332, u, 8\right)}, u, 4\right)\right) \cdot u \]
              5. Applied rewrites73.0%

                \[\leadsto \color{blue}{\left(s \cdot \mathsf{fma}\left(\mathsf{fma}\left(21.333333333333332, u, 8\right), u, 4\right)\right) \cdot u} \]
              6. Taylor expanded in u around inf

                \[\leadsto \left(s \cdot \left({u}^{2} \cdot \left(\frac{64}{3} + \left(8 \cdot \frac{1}{u} + \frac{4}{{u}^{2}}\right)\right)\right)\right) \cdot u \]
              7. Step-by-step derivation
                1. Applied rewrites89.9%

                  \[\leadsto \left(s \cdot \left(\left(\left(\left(21.333333333333332 + \frac{4}{u \cdot u}\right) + \frac{8}{u}\right) \cdot u\right) \cdot u\right)\right) \cdot u \]
                2. Taylor expanded in u around -inf

                  \[\leadsto \left(s \cdot \left(\left(-1 \cdot \left(u \cdot \left(-1 \cdot \frac{8 + 4 \cdot \frac{1}{u}}{u} - \frac{64}{3}\right)\right)\right) \cdot u\right)\right) \cdot u \]
                3. Step-by-step derivation
                  1. Applied rewrites90.1%

                    \[\leadsto \left(s \cdot \left(\left(\left(-u\right) \cdot \left(-21.333333333333332 - \frac{\frac{4}{u} + 8}{u}\right)\right) \cdot u\right)\right) \cdot u \]
                  2. Step-by-step derivation
                    1. Applied rewrites90.1%

                      \[\leadsto \left(s \cdot \left(\left(\left(-u\right) \cdot -21.333333333333332 + \left(-u\right) \cdot \frac{-\left(8 + \frac{4}{u}\right)}{u}\right) \cdot u\right)\right) \cdot u \]
                    2. Final simplification90.1%

                      \[\leadsto \left(\left(\left(\frac{\frac{4}{u} + 8}{u} \cdot u - -21.333333333333332 \cdot u\right) \cdot u\right) \cdot s\right) \cdot u \]
                    3. Add Preprocessing

                    Alternative 4: 90.8% accurate, 2.6× speedup?

                    \[\begin{array}{l} \\ \left(\left(\left(\left(\frac{\frac{4}{u} + 8}{u} - -21.333333333333332\right) \cdot u\right) \cdot u\right) \cdot s\right) \cdot u \end{array} \]
                    (FPCore (s u)
                     :precision binary32
                     (* (* (* (* (- (/ (+ (/ 4.0 u) 8.0) u) -21.333333333333332) u) u) s) u))
                    float code(float s, float u) {
                    	return (((((((4.0f / u) + 8.0f) / u) - -21.333333333333332f) * u) * u) * s) * u;
                    }
                    
                    real(4) function code(s, u)
                        real(4), intent (in) :: s
                        real(4), intent (in) :: u
                        code = (((((((4.0e0 / u) + 8.0e0) / u) - (-21.333333333333332e0)) * u) * u) * s) * u
                    end function
                    
                    function code(s, u)
                    	return Float32(Float32(Float32(Float32(Float32(Float32(Float32(Float32(Float32(4.0) / u) + Float32(8.0)) / u) - Float32(-21.333333333333332)) * u) * u) * s) * u)
                    end
                    
                    function tmp = code(s, u)
                    	tmp = (((((((single(4.0) / u) + single(8.0)) / u) - single(-21.333333333333332)) * u) * u) * s) * u;
                    end
                    
                    \begin{array}{l}
                    
                    \\
                    \left(\left(\left(\left(\frac{\frac{4}{u} + 8}{u} - -21.333333333333332\right) \cdot u\right) \cdot u\right) \cdot s\right) \cdot u
                    \end{array}
                    
                    Derivation
                    1. Initial program 61.5%

                      \[s \cdot \log \left(\frac{1}{1 - 4 \cdot u}\right) \]
                    2. Add Preprocessing
                    3. Taylor expanded in u around 0

                      \[\leadsto \color{blue}{u \cdot \left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right)} \]
                    4. Step-by-step derivation
                      1. *-commutativeN/A

                        \[\leadsto \color{blue}{\left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u} \]
                      2. lower-*.f32N/A

                        \[\leadsto \color{blue}{\left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u} \]
                      3. *-commutativeN/A

                        \[\leadsto \left(\color{blue}{s \cdot 4} + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u \]
                      4. distribute-rgt-inN/A

                        \[\leadsto \left(s \cdot 4 + \color{blue}{\left(\left(8 \cdot s\right) \cdot u + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)}\right) \cdot u \]
                      5. associate-*r*N/A

                        \[\leadsto \left(s \cdot 4 + \left(\color{blue}{8 \cdot \left(s \cdot u\right)} + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)\right) \cdot u \]
                      6. *-commutativeN/A

                        \[\leadsto \left(s \cdot 4 + \left(\color{blue}{\left(s \cdot u\right) \cdot 8} + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)\right) \cdot u \]
                      7. *-commutativeN/A

                        \[\leadsto \left(s \cdot 4 + \left(\left(s \cdot u\right) \cdot 8 + \color{blue}{\left(\left(s \cdot u\right) \cdot \frac{64}{3}\right)} \cdot u\right)\right) \cdot u \]
                      8. associate-*l*N/A

                        \[\leadsto \left(s \cdot 4 + \left(\left(s \cdot u\right) \cdot 8 + \color{blue}{\left(s \cdot u\right) \cdot \left(\frac{64}{3} \cdot u\right)}\right)\right) \cdot u \]
                      9. distribute-lft-outN/A

                        \[\leadsto \left(s \cdot 4 + \color{blue}{\left(s \cdot u\right) \cdot \left(8 + \frac{64}{3} \cdot u\right)}\right) \cdot u \]
                      10. associate-*l*N/A

                        \[\leadsto \left(s \cdot 4 + \color{blue}{s \cdot \left(u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)}\right) \cdot u \]
                      11. distribute-lft-inN/A

                        \[\leadsto \color{blue}{\left(s \cdot \left(4 + u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)\right)} \cdot u \]
                      12. lower-*.f32N/A

                        \[\leadsto \color{blue}{\left(s \cdot \left(4 + u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)\right)} \cdot u \]
                      13. +-commutativeN/A

                        \[\leadsto \left(s \cdot \color{blue}{\left(u \cdot \left(8 + \frac{64}{3} \cdot u\right) + 4\right)}\right) \cdot u \]
                      14. *-commutativeN/A

                        \[\leadsto \left(s \cdot \left(\color{blue}{\left(8 + \frac{64}{3} \cdot u\right) \cdot u} + 4\right)\right) \cdot u \]
                      15. lower-fma.f32N/A

                        \[\leadsto \left(s \cdot \color{blue}{\mathsf{fma}\left(8 + \frac{64}{3} \cdot u, u, 4\right)}\right) \cdot u \]
                      16. +-commutativeN/A

                        \[\leadsto \left(s \cdot \mathsf{fma}\left(\color{blue}{\frac{64}{3} \cdot u + 8}, u, 4\right)\right) \cdot u \]
                      17. lower-fma.f3273.0

                        \[\leadsto \left(s \cdot \mathsf{fma}\left(\color{blue}{\mathsf{fma}\left(21.333333333333332, u, 8\right)}, u, 4\right)\right) \cdot u \]
                    5. Applied rewrites73.0%

                      \[\leadsto \color{blue}{\left(s \cdot \mathsf{fma}\left(\mathsf{fma}\left(21.333333333333332, u, 8\right), u, 4\right)\right) \cdot u} \]
                    6. Taylor expanded in u around inf

                      \[\leadsto \left(s \cdot \left({u}^{2} \cdot \left(\frac{64}{3} + \left(8 \cdot \frac{1}{u} + \frac{4}{{u}^{2}}\right)\right)\right)\right) \cdot u \]
                    7. Step-by-step derivation
                      1. Applied rewrites89.9%

                        \[\leadsto \left(s \cdot \left(\left(\left(\left(21.333333333333332 + \frac{4}{u \cdot u}\right) + \frac{8}{u}\right) \cdot u\right) \cdot u\right)\right) \cdot u \]
                      2. Taylor expanded in u around -inf

                        \[\leadsto \left(s \cdot \left(\left(-1 \cdot \left(u \cdot \left(-1 \cdot \frac{8 + 4 \cdot \frac{1}{u}}{u} - \frac{64}{3}\right)\right)\right) \cdot u\right)\right) \cdot u \]
                      3. Step-by-step derivation
                        1. Applied rewrites90.1%

                          \[\leadsto \left(s \cdot \left(\left(\left(-u\right) \cdot \left(-21.333333333333332 - \frac{\frac{4}{u} + 8}{u}\right)\right) \cdot u\right)\right) \cdot u \]
                        2. Final simplification90.1%

                          \[\leadsto \left(\left(\left(\left(\frac{\frac{4}{u} + 8}{u} - -21.333333333333332\right) \cdot u\right) \cdot u\right) \cdot s\right) \cdot u \]
                        3. Add Preprocessing

                        Alternative 5: 90.5% accurate, 2.6× speedup?

                        \[\begin{array}{l} \\ \left(\left(\left(\frac{\frac{4}{u} + 8}{u} - -21.333333333333332\right) \cdot u\right) \cdot u\right) \cdot \left(s \cdot u\right) \end{array} \]
                        (FPCore (s u)
                         :precision binary32
                         (* (* (* (- (/ (+ (/ 4.0 u) 8.0) u) -21.333333333333332) u) u) (* s u)))
                        float code(float s, float u) {
                        	return ((((((4.0f / u) + 8.0f) / u) - -21.333333333333332f) * u) * u) * (s * u);
                        }
                        
                        real(4) function code(s, u)
                            real(4), intent (in) :: s
                            real(4), intent (in) :: u
                            code = ((((((4.0e0 / u) + 8.0e0) / u) - (-21.333333333333332e0)) * u) * u) * (s * u)
                        end function
                        
                        function code(s, u)
                        	return Float32(Float32(Float32(Float32(Float32(Float32(Float32(Float32(4.0) / u) + Float32(8.0)) / u) - Float32(-21.333333333333332)) * u) * u) * Float32(s * u))
                        end
                        
                        function tmp = code(s, u)
                        	tmp = ((((((single(4.0) / u) + single(8.0)) / u) - single(-21.333333333333332)) * u) * u) * (s * u);
                        end
                        
                        \begin{array}{l}
                        
                        \\
                        \left(\left(\left(\frac{\frac{4}{u} + 8}{u} - -21.333333333333332\right) \cdot u\right) \cdot u\right) \cdot \left(s \cdot u\right)
                        \end{array}
                        
                        Derivation
                        1. Initial program 61.5%

                          \[s \cdot \log \left(\frac{1}{1 - 4 \cdot u}\right) \]
                        2. Add Preprocessing
                        3. Taylor expanded in u around 0

                          \[\leadsto \color{blue}{u \cdot \left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right)} \]
                        4. Step-by-step derivation
                          1. *-commutativeN/A

                            \[\leadsto \color{blue}{\left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u} \]
                          2. lower-*.f32N/A

                            \[\leadsto \color{blue}{\left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u} \]
                          3. *-commutativeN/A

                            \[\leadsto \left(\color{blue}{s \cdot 4} + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u \]
                          4. distribute-rgt-inN/A

                            \[\leadsto \left(s \cdot 4 + \color{blue}{\left(\left(8 \cdot s\right) \cdot u + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)}\right) \cdot u \]
                          5. associate-*r*N/A

                            \[\leadsto \left(s \cdot 4 + \left(\color{blue}{8 \cdot \left(s \cdot u\right)} + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)\right) \cdot u \]
                          6. *-commutativeN/A

                            \[\leadsto \left(s \cdot 4 + \left(\color{blue}{\left(s \cdot u\right) \cdot 8} + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)\right) \cdot u \]
                          7. *-commutativeN/A

                            \[\leadsto \left(s \cdot 4 + \left(\left(s \cdot u\right) \cdot 8 + \color{blue}{\left(\left(s \cdot u\right) \cdot \frac{64}{3}\right)} \cdot u\right)\right) \cdot u \]
                          8. associate-*l*N/A

                            \[\leadsto \left(s \cdot 4 + \left(\left(s \cdot u\right) \cdot 8 + \color{blue}{\left(s \cdot u\right) \cdot \left(\frac{64}{3} \cdot u\right)}\right)\right) \cdot u \]
                          9. distribute-lft-outN/A

                            \[\leadsto \left(s \cdot 4 + \color{blue}{\left(s \cdot u\right) \cdot \left(8 + \frac{64}{3} \cdot u\right)}\right) \cdot u \]
                          10. associate-*l*N/A

                            \[\leadsto \left(s \cdot 4 + \color{blue}{s \cdot \left(u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)}\right) \cdot u \]
                          11. distribute-lft-inN/A

                            \[\leadsto \color{blue}{\left(s \cdot \left(4 + u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)\right)} \cdot u \]
                          12. lower-*.f32N/A

                            \[\leadsto \color{blue}{\left(s \cdot \left(4 + u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)\right)} \cdot u \]
                          13. +-commutativeN/A

                            \[\leadsto \left(s \cdot \color{blue}{\left(u \cdot \left(8 + \frac{64}{3} \cdot u\right) + 4\right)}\right) \cdot u \]
                          14. *-commutativeN/A

                            \[\leadsto \left(s \cdot \left(\color{blue}{\left(8 + \frac{64}{3} \cdot u\right) \cdot u} + 4\right)\right) \cdot u \]
                          15. lower-fma.f32N/A

                            \[\leadsto \left(s \cdot \color{blue}{\mathsf{fma}\left(8 + \frac{64}{3} \cdot u, u, 4\right)}\right) \cdot u \]
                          16. +-commutativeN/A

                            \[\leadsto \left(s \cdot \mathsf{fma}\left(\color{blue}{\frac{64}{3} \cdot u + 8}, u, 4\right)\right) \cdot u \]
                          17. lower-fma.f3273.0

                            \[\leadsto \left(s \cdot \mathsf{fma}\left(\color{blue}{\mathsf{fma}\left(21.333333333333332, u, 8\right)}, u, 4\right)\right) \cdot u \]
                        5. Applied rewrites73.0%

                          \[\leadsto \color{blue}{\left(s \cdot \mathsf{fma}\left(\mathsf{fma}\left(21.333333333333332, u, 8\right), u, 4\right)\right) \cdot u} \]
                        6. Taylor expanded in u around inf

                          \[\leadsto \left(s \cdot \left({u}^{2} \cdot \left(\frac{64}{3} + \left(8 \cdot \frac{1}{u} + \frac{4}{{u}^{2}}\right)\right)\right)\right) \cdot u \]
                        7. Step-by-step derivation
                          1. Applied rewrites89.9%

                            \[\leadsto \left(s \cdot \left(\left(\left(\left(21.333333333333332 + \frac{4}{u \cdot u}\right) + \frac{8}{u}\right) \cdot u\right) \cdot u\right)\right) \cdot u \]
                          2. Taylor expanded in u around -inf

                            \[\leadsto \left(s \cdot \left(\left(-1 \cdot \left(u \cdot \left(-1 \cdot \frac{8 + 4 \cdot \frac{1}{u}}{u} - \frac{64}{3}\right)\right)\right) \cdot u\right)\right) \cdot u \]
                          3. Step-by-step derivation
                            1. Applied rewrites90.1%

                              \[\leadsto \left(s \cdot \left(\left(\left(-u\right) \cdot \left(-21.333333333333332 - \frac{\frac{4}{u} + 8}{u}\right)\right) \cdot u\right)\right) \cdot u \]
                            2. Step-by-step derivation
                              1. Applied rewrites89.8%

                                \[\leadsto \color{blue}{\left(s \cdot u\right) \cdot \left(\left(\left(-21.333333333333332 - \frac{8 + \frac{4}{u}}{u}\right) \cdot \left(-u\right)\right) \cdot u\right)} \]
                              2. Final simplification89.8%

                                \[\leadsto \left(\left(\left(\frac{\frac{4}{u} + 8}{u} - -21.333333333333332\right) \cdot u\right) \cdot u\right) \cdot \left(s \cdot u\right) \]
                              3. Add Preprocessing

                              Alternative 6: 74.1% accurate, 11.4× speedup?

                              \[\begin{array}{l} \\ \left(u \cdot 4\right) \cdot s \end{array} \]
                              (FPCore (s u) :precision binary32 (* (* u 4.0) s))
                              float code(float s, float u) {
                              	return (u * 4.0f) * s;
                              }
                              
                              real(4) function code(s, u)
                                  real(4), intent (in) :: s
                                  real(4), intent (in) :: u
                                  code = (u * 4.0e0) * s
                              end function
                              
                              function code(s, u)
                              	return Float32(Float32(u * Float32(4.0)) * s)
                              end
                              
                              function tmp = code(s, u)
                              	tmp = (u * single(4.0)) * s;
                              end
                              
                              \begin{array}{l}
                              
                              \\
                              \left(u \cdot 4\right) \cdot s
                              \end{array}
                              
                              Derivation
                              1. Initial program 61.5%

                                \[s \cdot \log \left(\frac{1}{1 - 4 \cdot u}\right) \]
                              2. Add Preprocessing
                              3. Taylor expanded in u around 0

                                \[\leadsto s \cdot \color{blue}{\left(4 \cdot u\right)} \]
                              4. Step-by-step derivation
                                1. *-commutativeN/A

                                  \[\leadsto s \cdot \color{blue}{\left(u \cdot 4\right)} \]
                                2. lower-*.f3273.0

                                  \[\leadsto s \cdot \color{blue}{\left(u \cdot 4\right)} \]
                              5. Applied rewrites73.0%

                                \[\leadsto s \cdot \color{blue}{\left(u \cdot 4\right)} \]
                              6. Final simplification73.0%

                                \[\leadsto \left(u \cdot 4\right) \cdot s \]
                              7. Add Preprocessing

                              Alternative 7: 73.9% accurate, 11.4× speedup?

                              \[\begin{array}{l} \\ 4 \cdot \left(s \cdot u\right) \end{array} \]
                              (FPCore (s u) :precision binary32 (* 4.0 (* s u)))
                              float code(float s, float u) {
                              	return 4.0f * (s * u);
                              }
                              
                              real(4) function code(s, u)
                                  real(4), intent (in) :: s
                                  real(4), intent (in) :: u
                                  code = 4.0e0 * (s * u)
                              end function
                              
                              function code(s, u)
                              	return Float32(Float32(4.0) * Float32(s * u))
                              end
                              
                              function tmp = code(s, u)
                              	tmp = single(4.0) * (s * u);
                              end
                              
                              \begin{array}{l}
                              
                              \\
                              4 \cdot \left(s \cdot u\right)
                              \end{array}
                              
                              Derivation
                              1. Initial program 61.5%

                                \[s \cdot \log \left(\frac{1}{1 - 4 \cdot u}\right) \]
                              2. Add Preprocessing
                              3. Taylor expanded in u around 0

                                \[\leadsto \color{blue}{u \cdot \left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right)} \]
                              4. Step-by-step derivation
                                1. *-commutativeN/A

                                  \[\leadsto \color{blue}{\left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u} \]
                                2. lower-*.f32N/A

                                  \[\leadsto \color{blue}{\left(4 \cdot s + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u} \]
                                3. *-commutativeN/A

                                  \[\leadsto \left(\color{blue}{s \cdot 4} + u \cdot \left(8 \cdot s + \frac{64}{3} \cdot \left(s \cdot u\right)\right)\right) \cdot u \]
                                4. distribute-rgt-inN/A

                                  \[\leadsto \left(s \cdot 4 + \color{blue}{\left(\left(8 \cdot s\right) \cdot u + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)}\right) \cdot u \]
                                5. associate-*r*N/A

                                  \[\leadsto \left(s \cdot 4 + \left(\color{blue}{8 \cdot \left(s \cdot u\right)} + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)\right) \cdot u \]
                                6. *-commutativeN/A

                                  \[\leadsto \left(s \cdot 4 + \left(\color{blue}{\left(s \cdot u\right) \cdot 8} + \left(\frac{64}{3} \cdot \left(s \cdot u\right)\right) \cdot u\right)\right) \cdot u \]
                                7. *-commutativeN/A

                                  \[\leadsto \left(s \cdot 4 + \left(\left(s \cdot u\right) \cdot 8 + \color{blue}{\left(\left(s \cdot u\right) \cdot \frac{64}{3}\right)} \cdot u\right)\right) \cdot u \]
                                8. associate-*l*N/A

                                  \[\leadsto \left(s \cdot 4 + \left(\left(s \cdot u\right) \cdot 8 + \color{blue}{\left(s \cdot u\right) \cdot \left(\frac{64}{3} \cdot u\right)}\right)\right) \cdot u \]
                                9. distribute-lft-outN/A

                                  \[\leadsto \left(s \cdot 4 + \color{blue}{\left(s \cdot u\right) \cdot \left(8 + \frac{64}{3} \cdot u\right)}\right) \cdot u \]
                                10. associate-*l*N/A

                                  \[\leadsto \left(s \cdot 4 + \color{blue}{s \cdot \left(u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)}\right) \cdot u \]
                                11. distribute-lft-inN/A

                                  \[\leadsto \color{blue}{\left(s \cdot \left(4 + u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)\right)} \cdot u \]
                                12. lower-*.f32N/A

                                  \[\leadsto \color{blue}{\left(s \cdot \left(4 + u \cdot \left(8 + \frac{64}{3} \cdot u\right)\right)\right)} \cdot u \]
                                13. +-commutativeN/A

                                  \[\leadsto \left(s \cdot \color{blue}{\left(u \cdot \left(8 + \frac{64}{3} \cdot u\right) + 4\right)}\right) \cdot u \]
                                14. *-commutativeN/A

                                  \[\leadsto \left(s \cdot \left(\color{blue}{\left(8 + \frac{64}{3} \cdot u\right) \cdot u} + 4\right)\right) \cdot u \]
                                15. lower-fma.f32N/A

                                  \[\leadsto \left(s \cdot \color{blue}{\mathsf{fma}\left(8 + \frac{64}{3} \cdot u, u, 4\right)}\right) \cdot u \]
                                16. +-commutativeN/A

                                  \[\leadsto \left(s \cdot \mathsf{fma}\left(\color{blue}{\frac{64}{3} \cdot u + 8}, u, 4\right)\right) \cdot u \]
                                17. lower-fma.f3273.0

                                  \[\leadsto \left(s \cdot \mathsf{fma}\left(\color{blue}{\mathsf{fma}\left(21.333333333333332, u, 8\right)}, u, 4\right)\right) \cdot u \]
                              5. Applied rewrites73.0%

                                \[\leadsto \color{blue}{\left(s \cdot \mathsf{fma}\left(\mathsf{fma}\left(21.333333333333332, u, 8\right), u, 4\right)\right) \cdot u} \]
                              6. Step-by-step derivation
                                1. Applied rewrites72.8%

                                  \[\leadsto \mathsf{fma}\left(\mathsf{fma}\left(21.333333333333332, u, 8\right), u, 4\right) \cdot \color{blue}{\left(s \cdot u\right)} \]
                                2. Taylor expanded in u around 0

                                  \[\leadsto 4 \cdot \left(\color{blue}{s} \cdot u\right) \]
                                3. Step-by-step derivation
                                  1. Applied rewrites72.8%

                                    \[\leadsto 4 \cdot \left(\color{blue}{s} \cdot u\right) \]
                                  2. Add Preprocessing

                                  Reproduce

                                  ?
                                  herbie shell --seed 2024255 
                                  (FPCore (s u)
                                    :name "Disney BSSRDF, sample scattering profile, lower"
                                    :precision binary32
                                    :pre (and (and (<= 0.0 s) (<= s 256.0)) (and (<= 2.328306437e-10 u) (<= u 0.25)))
                                    (* s (log (/ 1.0 (- 1.0 (* 4.0 u))))))