Beckmann Distribution sample, tan2theta, alphax == alphay

Percentage Accurate: 56.1% → 89.8%
Time: 7.9s
Alternatives: 6
Speedup: 10.5×

Specification

?
\[\left(0.0001 \leq \alpha \land \alpha \leq 1\right) \land \left(2.328306437 \cdot 10^{-10} \leq u0 \land u0 \leq 1\right)\]
\[\begin{array}{l} \\ \left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\right) \end{array} \]
(FPCore (alpha u0)
 :precision binary32
 (* (* (- alpha) alpha) (log (- 1.0 u0))))
float code(float alpha, float u0) {
	return (-alpha * alpha) * logf((1.0f - u0));
}
real(4) function code(alpha, u0)
    real(4), intent (in) :: alpha
    real(4), intent (in) :: u0
    code = (-alpha * alpha) * log((1.0e0 - u0))
end function
function code(alpha, u0)
	return Float32(Float32(Float32(-alpha) * alpha) * log(Float32(Float32(1.0) - u0)))
end
function tmp = code(alpha, u0)
	tmp = (-alpha * alpha) * log((single(1.0) - u0));
end
\begin{array}{l}

\\
\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\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 6 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: 56.1% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\right) \end{array} \]
(FPCore (alpha u0)
 :precision binary32
 (* (* (- alpha) alpha) (log (- 1.0 u0))))
float code(float alpha, float u0) {
	return (-alpha * alpha) * logf((1.0f - u0));
}
real(4) function code(alpha, u0)
    real(4), intent (in) :: alpha
    real(4), intent (in) :: u0
    code = (-alpha * alpha) * log((1.0e0 - u0))
end function
function code(alpha, u0)
	return Float32(Float32(Float32(-alpha) * alpha) * log(Float32(Float32(1.0) - u0)))
end
function tmp = code(alpha, u0)
	tmp = (-alpha * alpha) * log((single(1.0) - u0));
end
\begin{array}{l}

\\
\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\right)
\end{array}

Alternative 1: 89.8% accurate, 0.8× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;1 - u0 \leq 0.9998199939727783:\\ \;\;\;\;\log \left(1 - u0\right) \cdot \frac{\left(\alpha \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}{\alpha \cdot \alpha}\\ \mathbf{else}:\\ \;\;\;\;\frac{\left(\alpha \cdot \alpha\right) \cdot \alpha}{\alpha} \cdot u0\\ \end{array} \end{array} \]
(FPCore (alpha u0)
 :precision binary32
 (if (<= (- 1.0 u0) 0.9998199939727783)
   (*
    (log (- 1.0 u0))
    (/ (* (* alpha alpha) (* (- alpha) alpha)) (* alpha alpha)))
   (* (/ (* (* alpha alpha) alpha) alpha) u0)))
float code(float alpha, float u0) {
	float tmp;
	if ((1.0f - u0) <= 0.9998199939727783f) {
		tmp = logf((1.0f - u0)) * (((alpha * alpha) * (-alpha * alpha)) / (alpha * alpha));
	} else {
		tmp = (((alpha * alpha) * alpha) / alpha) * u0;
	}
	return tmp;
}
real(4) function code(alpha, u0)
    real(4), intent (in) :: alpha
    real(4), intent (in) :: u0
    real(4) :: tmp
    if ((1.0e0 - u0) <= 0.9998199939727783e0) then
        tmp = log((1.0e0 - u0)) * (((alpha * alpha) * (-alpha * alpha)) / (alpha * alpha))
    else
        tmp = (((alpha * alpha) * alpha) / alpha) * u0
    end if
    code = tmp
end function
function code(alpha, u0)
	tmp = Float32(0.0)
	if (Float32(Float32(1.0) - u0) <= Float32(0.9998199939727783))
		tmp = Float32(log(Float32(Float32(1.0) - u0)) * Float32(Float32(Float32(alpha * alpha) * Float32(Float32(-alpha) * alpha)) / Float32(alpha * alpha)));
	else
		tmp = Float32(Float32(Float32(Float32(alpha * alpha) * alpha) / alpha) * u0);
	end
	return tmp
end
function tmp_2 = code(alpha, u0)
	tmp = single(0.0);
	if ((single(1.0) - u0) <= single(0.9998199939727783))
		tmp = log((single(1.0) - u0)) * (((alpha * alpha) * (-alpha * alpha)) / (alpha * alpha));
	else
		tmp = (((alpha * alpha) * alpha) / alpha) * u0;
	end
	tmp_2 = tmp;
end
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;1 - u0 \leq 0.9998199939727783:\\
\;\;\;\;\log \left(1 - u0\right) \cdot \frac{\left(\alpha \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}{\alpha \cdot \alpha}\\

\mathbf{else}:\\
\;\;\;\;\frac{\left(\alpha \cdot \alpha\right) \cdot \alpha}{\alpha} \cdot u0\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (-.f32 #s(literal 1 binary32) u0) < 0.999819994

    1. Initial program 89.0%

      \[\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\right) \]
    2. Add Preprocessing
    3. Step-by-step derivation
      1. +-lft-identityN/A

        \[\leadsto \color{blue}{\left(0 + \left(-\alpha\right) \cdot \alpha\right)} \cdot \log \left(1 - u0\right) \]
      2. flip-+N/A

        \[\leadsto \color{blue}{\frac{0 \cdot 0 - \left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}{0 - \left(-\alpha\right) \cdot \alpha}} \cdot \log \left(1 - u0\right) \]
      3. neg-sub0N/A

        \[\leadsto \frac{0 \cdot 0 - \left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}{\color{blue}{\mathsf{neg}\left(\left(-\alpha\right) \cdot \alpha\right)}} \cdot \log \left(1 - u0\right) \]
      4. lift-*.f32N/A

        \[\leadsto \frac{0 \cdot 0 - \left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}{\mathsf{neg}\left(\color{blue}{\left(-\alpha\right) \cdot \alpha}\right)} \cdot \log \left(1 - u0\right) \]
      5. lift-neg.f32N/A

        \[\leadsto \frac{0 \cdot 0 - \left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}{\mathsf{neg}\left(\color{blue}{\left(\mathsf{neg}\left(\alpha\right)\right)} \cdot \alpha\right)} \cdot \log \left(1 - u0\right) \]
      6. distribute-lft-neg-outN/A

        \[\leadsto \frac{0 \cdot 0 - \left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}{\mathsf{neg}\left(\color{blue}{\left(\mathsf{neg}\left(\alpha \cdot \alpha\right)\right)}\right)} \cdot \log \left(1 - u0\right) \]
      7. remove-double-negN/A

        \[\leadsto \frac{0 \cdot 0 - \left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}{\color{blue}{\alpha \cdot \alpha}} \cdot \log \left(1 - u0\right) \]
      8. lower-/.f32N/A

        \[\leadsto \color{blue}{\frac{0 \cdot 0 - \left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}{\alpha \cdot \alpha}} \cdot \log \left(1 - u0\right) \]
      9. metadata-evalN/A

        \[\leadsto \frac{\color{blue}{0} - \left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}{\alpha \cdot \alpha} \cdot \log \left(1 - u0\right) \]
      10. lower--.f32N/A

        \[\leadsto \frac{\color{blue}{0 - \left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}}{\alpha \cdot \alpha} \cdot \log \left(1 - u0\right) \]
      11. lower-*.f32N/A

        \[\leadsto \frac{0 - \color{blue}{\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}}{\alpha \cdot \alpha} \cdot \log \left(1 - u0\right) \]
      12. lower-*.f3289.1

        \[\leadsto \frac{0 - \left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}{\color{blue}{\alpha \cdot \alpha}} \cdot \log \left(1 - u0\right) \]
    4. Applied rewrites89.1%

      \[\leadsto \color{blue}{\frac{0 - \left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}{\alpha \cdot \alpha}} \cdot \log \left(1 - u0\right) \]
    5. Step-by-step derivation
      1. lift--.f32N/A

        \[\leadsto \frac{\color{blue}{0 - \left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}}{\alpha \cdot \alpha} \cdot \log \left(1 - u0\right) \]
      2. sub0-negN/A

        \[\leadsto \frac{\color{blue}{\mathsf{neg}\left(\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)\right)}}{\alpha \cdot \alpha} \cdot \log \left(1 - u0\right) \]
      3. lift-*.f32N/A

        \[\leadsto \frac{\mathsf{neg}\left(\color{blue}{\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}\right)}{\alpha \cdot \alpha} \cdot \log \left(1 - u0\right) \]
      4. distribute-rgt-neg-inN/A

        \[\leadsto \frac{\color{blue}{\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\mathsf{neg}\left(\left(-\alpha\right) \cdot \alpha\right)\right)}}{\alpha \cdot \alpha} \cdot \log \left(1 - u0\right) \]
      5. lift-*.f32N/A

        \[\leadsto \frac{\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\mathsf{neg}\left(\color{blue}{\left(-\alpha\right) \cdot \alpha}\right)\right)}{\alpha \cdot \alpha} \cdot \log \left(1 - u0\right) \]
      6. lift-neg.f32N/A

        \[\leadsto \frac{\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\mathsf{neg}\left(\color{blue}{\left(\mathsf{neg}\left(\alpha\right)\right)} \cdot \alpha\right)\right)}{\alpha \cdot \alpha} \cdot \log \left(1 - u0\right) \]
      7. distribute-lft-neg-outN/A

        \[\leadsto \frac{\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\mathsf{neg}\left(\color{blue}{\left(\mathsf{neg}\left(\alpha \cdot \alpha\right)\right)}\right)\right)}{\alpha \cdot \alpha} \cdot \log \left(1 - u0\right) \]
      8. lift-*.f32N/A

        \[\leadsto \frac{\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\mathsf{neg}\left(\left(\mathsf{neg}\left(\color{blue}{\alpha \cdot \alpha}\right)\right)\right)\right)}{\alpha \cdot \alpha} \cdot \log \left(1 - u0\right) \]
      9. remove-double-negN/A

        \[\leadsto \frac{\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \color{blue}{\left(\alpha \cdot \alpha\right)}}{\alpha \cdot \alpha} \cdot \log \left(1 - u0\right) \]
      10. lower-*.f3289.1

        \[\leadsto \frac{\color{blue}{\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\alpha \cdot \alpha\right)}}{\alpha \cdot \alpha} \cdot \log \left(1 - u0\right) \]
    6. Applied rewrites89.1%

      \[\leadsto \frac{\color{blue}{\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \left(\alpha \cdot \alpha\right)}}{\alpha \cdot \alpha} \cdot \log \left(1 - u0\right) \]

    if 0.999819994 < (-.f32 #s(literal 1 binary32) u0)

    1. Initial program 35.3%

      \[\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\right) \]
    2. Add Preprocessing
    3. Taylor expanded in u0 around 0

      \[\leadsto \color{blue}{{\alpha}^{2} \cdot u0} \]
    4. Step-by-step derivation
      1. *-commutativeN/A

        \[\leadsto \color{blue}{u0 \cdot {\alpha}^{2}} \]
      2. lower-*.f32N/A

        \[\leadsto \color{blue}{u0 \cdot {\alpha}^{2}} \]
      3. unpow2N/A

        \[\leadsto u0 \cdot \color{blue}{\left(\alpha \cdot \alpha\right)} \]
      4. lower-*.f3291.2

        \[\leadsto u0 \cdot \color{blue}{\left(\alpha \cdot \alpha\right)} \]
    5. Applied rewrites91.2%

      \[\leadsto \color{blue}{u0 \cdot \left(\alpha \cdot \alpha\right)} \]
    6. Step-by-step derivation
      1. Applied rewrites90.8%

        \[\leadsto u0 \cdot \left(\frac{-1}{{\alpha}^{6}} \cdot \color{blue}{\frac{-{\alpha}^{4}}{{\alpha}^{-4}}}\right) \]
      2. Step-by-step derivation
        1. Applied rewrites91.1%

          \[\leadsto u0 \cdot \left(\frac{\alpha \cdot \alpha}{\alpha} \cdot \color{blue}{\frac{\alpha \cdot \alpha}{\alpha}}\right) \]
        2. Step-by-step derivation
          1. Applied rewrites91.2%

            \[\leadsto u0 \cdot \frac{\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \alpha}{\color{blue}{-\alpha}} \]
        3. Recombined 2 regimes into one program.
        4. Final simplification90.4%

          \[\leadsto \begin{array}{l} \mathbf{if}\;1 - u0 \leq 0.9998199939727783:\\ \;\;\;\;\log \left(1 - u0\right) \cdot \frac{\left(\alpha \cdot \alpha\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}{\alpha \cdot \alpha}\\ \mathbf{else}:\\ \;\;\;\;\frac{\left(\alpha \cdot \alpha\right) \cdot \alpha}{\alpha} \cdot u0\\ \end{array} \]
        5. Add Preprocessing

        Alternative 2: 89.8% accurate, 0.9× speedup?

        \[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;1 - u0 \leq 0.9998199939727783:\\ \;\;\;\;\log \left(1 - u0\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)\\ \mathbf{else}:\\ \;\;\;\;\frac{\left(\alpha \cdot \alpha\right) \cdot \alpha}{\alpha} \cdot u0\\ \end{array} \end{array} \]
        (FPCore (alpha u0)
         :precision binary32
         (if (<= (- 1.0 u0) 0.9998199939727783)
           (* (log (- 1.0 u0)) (* (- alpha) alpha))
           (* (/ (* (* alpha alpha) alpha) alpha) u0)))
        float code(float alpha, float u0) {
        	float tmp;
        	if ((1.0f - u0) <= 0.9998199939727783f) {
        		tmp = logf((1.0f - u0)) * (-alpha * alpha);
        	} else {
        		tmp = (((alpha * alpha) * alpha) / alpha) * u0;
        	}
        	return tmp;
        }
        
        real(4) function code(alpha, u0)
            real(4), intent (in) :: alpha
            real(4), intent (in) :: u0
            real(4) :: tmp
            if ((1.0e0 - u0) <= 0.9998199939727783e0) then
                tmp = log((1.0e0 - u0)) * (-alpha * alpha)
            else
                tmp = (((alpha * alpha) * alpha) / alpha) * u0
            end if
            code = tmp
        end function
        
        function code(alpha, u0)
        	tmp = Float32(0.0)
        	if (Float32(Float32(1.0) - u0) <= Float32(0.9998199939727783))
        		tmp = Float32(log(Float32(Float32(1.0) - u0)) * Float32(Float32(-alpha) * alpha));
        	else
        		tmp = Float32(Float32(Float32(Float32(alpha * alpha) * alpha) / alpha) * u0);
        	end
        	return tmp
        end
        
        function tmp_2 = code(alpha, u0)
        	tmp = single(0.0);
        	if ((single(1.0) - u0) <= single(0.9998199939727783))
        		tmp = log((single(1.0) - u0)) * (-alpha * alpha);
        	else
        		tmp = (((alpha * alpha) * alpha) / alpha) * u0;
        	end
        	tmp_2 = tmp;
        end
        
        \begin{array}{l}
        
        \\
        \begin{array}{l}
        \mathbf{if}\;1 - u0 \leq 0.9998199939727783:\\
        \;\;\;\;\log \left(1 - u0\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)\\
        
        \mathbf{else}:\\
        \;\;\;\;\frac{\left(\alpha \cdot \alpha\right) \cdot \alpha}{\alpha} \cdot u0\\
        
        
        \end{array}
        \end{array}
        
        Derivation
        1. Split input into 2 regimes
        2. if (-.f32 #s(literal 1 binary32) u0) < 0.999819994

          1. Initial program 89.0%

            \[\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\right) \]
          2. Add Preprocessing

          if 0.999819994 < (-.f32 #s(literal 1 binary32) u0)

          1. Initial program 35.3%

            \[\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\right) \]
          2. Add Preprocessing
          3. Taylor expanded in u0 around 0

            \[\leadsto \color{blue}{{\alpha}^{2} \cdot u0} \]
          4. Step-by-step derivation
            1. *-commutativeN/A

              \[\leadsto \color{blue}{u0 \cdot {\alpha}^{2}} \]
            2. lower-*.f32N/A

              \[\leadsto \color{blue}{u0 \cdot {\alpha}^{2}} \]
            3. unpow2N/A

              \[\leadsto u0 \cdot \color{blue}{\left(\alpha \cdot \alpha\right)} \]
            4. lower-*.f3291.2

              \[\leadsto u0 \cdot \color{blue}{\left(\alpha \cdot \alpha\right)} \]
          5. Applied rewrites91.2%

            \[\leadsto \color{blue}{u0 \cdot \left(\alpha \cdot \alpha\right)} \]
          6. Step-by-step derivation
            1. Applied rewrites90.8%

              \[\leadsto u0 \cdot \left(\frac{-1}{{\alpha}^{6}} \cdot \color{blue}{\frac{-{\alpha}^{4}}{{\alpha}^{-4}}}\right) \]
            2. Step-by-step derivation
              1. Applied rewrites91.1%

                \[\leadsto u0 \cdot \left(\frac{\alpha \cdot \alpha}{\alpha} \cdot \color{blue}{\frac{\alpha \cdot \alpha}{\alpha}}\right) \]
              2. Step-by-step derivation
                1. Applied rewrites91.2%

                  \[\leadsto u0 \cdot \frac{\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \alpha}{\color{blue}{-\alpha}} \]
              3. Recombined 2 regimes into one program.
              4. Final simplification90.4%

                \[\leadsto \begin{array}{l} \mathbf{if}\;1 - u0 \leq 0.9998199939727783:\\ \;\;\;\;\log \left(1 - u0\right) \cdot \left(\left(-\alpha\right) \cdot \alpha\right)\\ \mathbf{else}:\\ \;\;\;\;\frac{\left(\alpha \cdot \alpha\right) \cdot \alpha}{\alpha} \cdot u0\\ \end{array} \]
              5. Add Preprocessing

              Alternative 3: 89.8% accurate, 1.0× speedup?

              \[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;u0 \leq 0.00018000000272877514:\\ \;\;\;\;\frac{\left(\alpha \cdot \alpha\right) \cdot \alpha}{\alpha} \cdot u0\\ \mathbf{else}:\\ \;\;\;\;\left(\log \left(1 - u0\right) \cdot \left(-\alpha\right)\right) \cdot \alpha\\ \end{array} \end{array} \]
              (FPCore (alpha u0)
               :precision binary32
               (if (<= u0 0.00018000000272877514)
                 (* (/ (* (* alpha alpha) alpha) alpha) u0)
                 (* (* (log (- 1.0 u0)) (- alpha)) alpha)))
              float code(float alpha, float u0) {
              	float tmp;
              	if (u0 <= 0.00018000000272877514f) {
              		tmp = (((alpha * alpha) * alpha) / alpha) * u0;
              	} else {
              		tmp = (logf((1.0f - u0)) * -alpha) * alpha;
              	}
              	return tmp;
              }
              
              real(4) function code(alpha, u0)
                  real(4), intent (in) :: alpha
                  real(4), intent (in) :: u0
                  real(4) :: tmp
                  if (u0 <= 0.00018000000272877514e0) then
                      tmp = (((alpha * alpha) * alpha) / alpha) * u0
                  else
                      tmp = (log((1.0e0 - u0)) * -alpha) * alpha
                  end if
                  code = tmp
              end function
              
              function code(alpha, u0)
              	tmp = Float32(0.0)
              	if (u0 <= Float32(0.00018000000272877514))
              		tmp = Float32(Float32(Float32(Float32(alpha * alpha) * alpha) / alpha) * u0);
              	else
              		tmp = Float32(Float32(log(Float32(Float32(1.0) - u0)) * Float32(-alpha)) * alpha);
              	end
              	return tmp
              end
              
              function tmp_2 = code(alpha, u0)
              	tmp = single(0.0);
              	if (u0 <= single(0.00018000000272877514))
              		tmp = (((alpha * alpha) * alpha) / alpha) * u0;
              	else
              		tmp = (log((single(1.0) - u0)) * -alpha) * alpha;
              	end
              	tmp_2 = tmp;
              end
              
              \begin{array}{l}
              
              \\
              \begin{array}{l}
              \mathbf{if}\;u0 \leq 0.00018000000272877514:\\
              \;\;\;\;\frac{\left(\alpha \cdot \alpha\right) \cdot \alpha}{\alpha} \cdot u0\\
              
              \mathbf{else}:\\
              \;\;\;\;\left(\log \left(1 - u0\right) \cdot \left(-\alpha\right)\right) \cdot \alpha\\
              
              
              \end{array}
              \end{array}
              
              Derivation
              1. Split input into 2 regimes
              2. if u0 < 1.80000003e-4

                1. Initial program 35.3%

                  \[\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\right) \]
                2. Add Preprocessing
                3. Taylor expanded in u0 around 0

                  \[\leadsto \color{blue}{{\alpha}^{2} \cdot u0} \]
                4. Step-by-step derivation
                  1. *-commutativeN/A

                    \[\leadsto \color{blue}{u0 \cdot {\alpha}^{2}} \]
                  2. lower-*.f32N/A

                    \[\leadsto \color{blue}{u0 \cdot {\alpha}^{2}} \]
                  3. unpow2N/A

                    \[\leadsto u0 \cdot \color{blue}{\left(\alpha \cdot \alpha\right)} \]
                  4. lower-*.f3291.2

                    \[\leadsto u0 \cdot \color{blue}{\left(\alpha \cdot \alpha\right)} \]
                5. Applied rewrites91.2%

                  \[\leadsto \color{blue}{u0 \cdot \left(\alpha \cdot \alpha\right)} \]
                6. Step-by-step derivation
                  1. Applied rewrites90.8%

                    \[\leadsto u0 \cdot \left(\frac{-1}{{\alpha}^{6}} \cdot \color{blue}{\frac{-{\alpha}^{4}}{{\alpha}^{-4}}}\right) \]
                  2. Step-by-step derivation
                    1. Applied rewrites91.1%

                      \[\leadsto u0 \cdot \left(\frac{\alpha \cdot \alpha}{\alpha} \cdot \color{blue}{\frac{\alpha \cdot \alpha}{\alpha}}\right) \]
                    2. Step-by-step derivation
                      1. Applied rewrites91.2%

                        \[\leadsto u0 \cdot \frac{\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \alpha}{\color{blue}{-\alpha}} \]

                      if 1.80000003e-4 < u0

                      1. Initial program 89.0%

                        \[\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\right) \]
                      2. Add Preprocessing
                      3. Taylor expanded in alpha around 0

                        \[\leadsto \color{blue}{-1 \cdot \left({\alpha}^{2} \cdot \log \left(1 - u0\right)\right)} \]
                      4. Step-by-step derivation
                        1. mul-1-negN/A

                          \[\leadsto \color{blue}{\mathsf{neg}\left({\alpha}^{2} \cdot \log \left(1 - u0\right)\right)} \]
                        2. unpow2N/A

                          \[\leadsto \mathsf{neg}\left(\color{blue}{\left(\alpha \cdot \alpha\right)} \cdot \log \left(1 - u0\right)\right) \]
                        3. associate-*l*N/A

                          \[\leadsto \mathsf{neg}\left(\color{blue}{\alpha \cdot \left(\alpha \cdot \log \left(1 - u0\right)\right)}\right) \]
                        4. distribute-rgt-neg-inN/A

                          \[\leadsto \color{blue}{\alpha \cdot \left(\mathsf{neg}\left(\alpha \cdot \log \left(1 - u0\right)\right)\right)} \]
                        5. *-commutativeN/A

                          \[\leadsto \color{blue}{\left(\mathsf{neg}\left(\alpha \cdot \log \left(1 - u0\right)\right)\right) \cdot \alpha} \]
                        6. lower-*.f32N/A

                          \[\leadsto \color{blue}{\left(\mathsf{neg}\left(\alpha \cdot \log \left(1 - u0\right)\right)\right) \cdot \alpha} \]
                        7. distribute-lft-neg-inN/A

                          \[\leadsto \color{blue}{\left(\left(\mathsf{neg}\left(\alpha\right)\right) \cdot \log \left(1 - u0\right)\right)} \cdot \alpha \]
                        8. mul-1-negN/A

                          \[\leadsto \left(\color{blue}{\left(-1 \cdot \alpha\right)} \cdot \log \left(1 - u0\right)\right) \cdot \alpha \]
                        9. lower-*.f32N/A

                          \[\leadsto \color{blue}{\left(\left(-1 \cdot \alpha\right) \cdot \log \left(1 - u0\right)\right)} \cdot \alpha \]
                        10. mul-1-negN/A

                          \[\leadsto \left(\color{blue}{\left(\mathsf{neg}\left(\alpha\right)\right)} \cdot \log \left(1 - u0\right)\right) \cdot \alpha \]
                        11. lower-neg.f32N/A

                          \[\leadsto \left(\color{blue}{\left(-\alpha\right)} \cdot \log \left(1 - u0\right)\right) \cdot \alpha \]
                        12. sub-negN/A

                          \[\leadsto \left(\left(-\alpha\right) \cdot \log \color{blue}{\left(1 + \left(\mathsf{neg}\left(u0\right)\right)\right)}\right) \cdot \alpha \]
                        13. lower-log1p.f32N/A

                          \[\leadsto \left(\left(-\alpha\right) \cdot \color{blue}{\mathsf{log1p}\left(\mathsf{neg}\left(u0\right)\right)}\right) \cdot \alpha \]
                        14. lower-neg.f3246.9

                          \[\leadsto \left(\left(-\alpha\right) \cdot \mathsf{log1p}\left(\color{blue}{-u0}\right)\right) \cdot \alpha \]
                      5. Applied rewrites46.9%

                        \[\leadsto \color{blue}{\left(\left(-\alpha\right) \cdot \mathsf{log1p}\left(-u0\right)\right) \cdot \alpha} \]
                      6. Step-by-step derivation
                        1. Applied rewrites88.8%

                          \[\leadsto \left(\left(-\alpha\right) \cdot \log \left(1 - u0\right)\right) \cdot \alpha \]
                      7. Recombined 2 regimes into one program.
                      8. Final simplification90.3%

                        \[\leadsto \begin{array}{l} \mathbf{if}\;u0 \leq 0.00018000000272877514:\\ \;\;\;\;\frac{\left(\alpha \cdot \alpha\right) \cdot \alpha}{\alpha} \cdot u0\\ \mathbf{else}:\\ \;\;\;\;\left(\log \left(1 - u0\right) \cdot \left(-\alpha\right)\right) \cdot \alpha\\ \end{array} \]
                      9. Add Preprocessing

                      Alternative 4: 74.3% accurate, 4.3× speedup?

                      \[\begin{array}{l} \\ \frac{\left(\alpha \cdot \alpha\right) \cdot \alpha}{\alpha} \cdot u0 \end{array} \]
                      (FPCore (alpha u0)
                       :precision binary32
                       (* (/ (* (* alpha alpha) alpha) alpha) u0))
                      float code(float alpha, float u0) {
                      	return (((alpha * alpha) * alpha) / alpha) * u0;
                      }
                      
                      real(4) function code(alpha, u0)
                          real(4), intent (in) :: alpha
                          real(4), intent (in) :: u0
                          code = (((alpha * alpha) * alpha) / alpha) * u0
                      end function
                      
                      function code(alpha, u0)
                      	return Float32(Float32(Float32(Float32(alpha * alpha) * alpha) / alpha) * u0)
                      end
                      
                      function tmp = code(alpha, u0)
                      	tmp = (((alpha * alpha) * alpha) / alpha) * u0;
                      end
                      
                      \begin{array}{l}
                      
                      \\
                      \frac{\left(\alpha \cdot \alpha\right) \cdot \alpha}{\alpha} \cdot u0
                      \end{array}
                      
                      Derivation
                      1. Initial program 56.1%

                        \[\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\right) \]
                      2. Add Preprocessing
                      3. Taylor expanded in u0 around 0

                        \[\leadsto \color{blue}{{\alpha}^{2} \cdot u0} \]
                      4. Step-by-step derivation
                        1. *-commutativeN/A

                          \[\leadsto \color{blue}{u0 \cdot {\alpha}^{2}} \]
                        2. lower-*.f32N/A

                          \[\leadsto \color{blue}{u0 \cdot {\alpha}^{2}} \]
                        3. unpow2N/A

                          \[\leadsto u0 \cdot \color{blue}{\left(\alpha \cdot \alpha\right)} \]
                        4. lower-*.f3274.1

                          \[\leadsto u0 \cdot \color{blue}{\left(\alpha \cdot \alpha\right)} \]
                      5. Applied rewrites74.1%

                        \[\leadsto \color{blue}{u0 \cdot \left(\alpha \cdot \alpha\right)} \]
                      6. Step-by-step derivation
                        1. Applied rewrites73.8%

                          \[\leadsto u0 \cdot \left(\frac{-1}{{\alpha}^{6}} \cdot \color{blue}{\frac{-{\alpha}^{4}}{{\alpha}^{-4}}}\right) \]
                        2. Step-by-step derivation
                          1. Applied rewrites74.0%

                            \[\leadsto u0 \cdot \left(\frac{\alpha \cdot \alpha}{\alpha} \cdot \color{blue}{\frac{\alpha \cdot \alpha}{\alpha}}\right) \]
                          2. Step-by-step derivation
                            1. Applied rewrites74.1%

                              \[\leadsto u0 \cdot \frac{\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \alpha}{\color{blue}{-\alpha}} \]
                            2. Final simplification74.1%

                              \[\leadsto \frac{\left(\alpha \cdot \alpha\right) \cdot \alpha}{\alpha} \cdot u0 \]
                            3. Add Preprocessing

                            Alternative 5: 74.3% accurate, 4.3× speedup?

                            \[\begin{array}{l} \\ \frac{\left(\alpha \cdot \alpha\right) \cdot u0}{\alpha} \cdot \alpha \end{array} \]
                            (FPCore (alpha u0)
                             :precision binary32
                             (* (/ (* (* alpha alpha) u0) alpha) alpha))
                            float code(float alpha, float u0) {
                            	return (((alpha * alpha) * u0) / alpha) * alpha;
                            }
                            
                            real(4) function code(alpha, u0)
                                real(4), intent (in) :: alpha
                                real(4), intent (in) :: u0
                                code = (((alpha * alpha) * u0) / alpha) * alpha
                            end function
                            
                            function code(alpha, u0)
                            	return Float32(Float32(Float32(Float32(alpha * alpha) * u0) / alpha) * alpha)
                            end
                            
                            function tmp = code(alpha, u0)
                            	tmp = (((alpha * alpha) * u0) / alpha) * alpha;
                            end
                            
                            \begin{array}{l}
                            
                            \\
                            \frac{\left(\alpha \cdot \alpha\right) \cdot u0}{\alpha} \cdot \alpha
                            \end{array}
                            
                            Derivation
                            1. Initial program 56.1%

                              \[\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\right) \]
                            2. Add Preprocessing
                            3. Taylor expanded in u0 around 0

                              \[\leadsto \color{blue}{{\alpha}^{2} \cdot u0} \]
                            4. Step-by-step derivation
                              1. *-commutativeN/A

                                \[\leadsto \color{blue}{u0 \cdot {\alpha}^{2}} \]
                              2. lower-*.f32N/A

                                \[\leadsto \color{blue}{u0 \cdot {\alpha}^{2}} \]
                              3. unpow2N/A

                                \[\leadsto u0 \cdot \color{blue}{\left(\alpha \cdot \alpha\right)} \]
                              4. lower-*.f3274.1

                                \[\leadsto u0 \cdot \color{blue}{\left(\alpha \cdot \alpha\right)} \]
                            5. Applied rewrites74.1%

                              \[\leadsto \color{blue}{u0 \cdot \left(\alpha \cdot \alpha\right)} \]
                            6. Step-by-step derivation
                              1. Applied rewrites74.0%

                                \[\leadsto \left(u0 \cdot \alpha\right) \cdot \color{blue}{\alpha} \]
                              2. Step-by-step derivation
                                1. Applied rewrites73.9%

                                  \[\leadsto \alpha \cdot \color{blue}{\frac{u0}{\frac{1}{\alpha}}} \]
                                2. Step-by-step derivation
                                  1. Applied rewrites74.1%

                                    \[\leadsto \alpha \cdot \frac{u0 \cdot \left(\left(-\alpha\right) \cdot \alpha\right)}{\color{blue}{-\alpha}} \]
                                  2. Final simplification74.1%

                                    \[\leadsto \frac{\left(\alpha \cdot \alpha\right) \cdot u0}{\alpha} \cdot \alpha \]
                                  3. Add Preprocessing

                                  Alternative 6: 74.4% accurate, 10.5× speedup?

                                  \[\begin{array}{l} \\ \left(\alpha \cdot \alpha\right) \cdot u0 \end{array} \]
                                  (FPCore (alpha u0) :precision binary32 (* (* alpha alpha) u0))
                                  float code(float alpha, float u0) {
                                  	return (alpha * alpha) * u0;
                                  }
                                  
                                  real(4) function code(alpha, u0)
                                      real(4), intent (in) :: alpha
                                      real(4), intent (in) :: u0
                                      code = (alpha * alpha) * u0
                                  end function
                                  
                                  function code(alpha, u0)
                                  	return Float32(Float32(alpha * alpha) * u0)
                                  end
                                  
                                  function tmp = code(alpha, u0)
                                  	tmp = (alpha * alpha) * u0;
                                  end
                                  
                                  \begin{array}{l}
                                  
                                  \\
                                  \left(\alpha \cdot \alpha\right) \cdot u0
                                  \end{array}
                                  
                                  Derivation
                                  1. Initial program 56.1%

                                    \[\left(\left(-\alpha\right) \cdot \alpha\right) \cdot \log \left(1 - u0\right) \]
                                  2. Add Preprocessing
                                  3. Taylor expanded in u0 around 0

                                    \[\leadsto \color{blue}{{\alpha}^{2} \cdot u0} \]
                                  4. Step-by-step derivation
                                    1. *-commutativeN/A

                                      \[\leadsto \color{blue}{u0 \cdot {\alpha}^{2}} \]
                                    2. lower-*.f32N/A

                                      \[\leadsto \color{blue}{u0 \cdot {\alpha}^{2}} \]
                                    3. unpow2N/A

                                      \[\leadsto u0 \cdot \color{blue}{\left(\alpha \cdot \alpha\right)} \]
                                    4. lower-*.f3274.1

                                      \[\leadsto u0 \cdot \color{blue}{\left(\alpha \cdot \alpha\right)} \]
                                  5. Applied rewrites74.1%

                                    \[\leadsto \color{blue}{u0 \cdot \left(\alpha \cdot \alpha\right)} \]
                                  6. Final simplification74.1%

                                    \[\leadsto \left(\alpha \cdot \alpha\right) \cdot u0 \]
                                  7. Add Preprocessing

                                  Reproduce

                                  ?
                                  herbie shell --seed 2024259 
                                  (FPCore (alpha u0)
                                    :name "Beckmann Distribution sample, tan2theta, alphax == alphay"
                                    :precision binary32
                                    :pre (and (and (<= 0.0001 alpha) (<= alpha 1.0)) (and (<= 2.328306437e-10 u0) (<= u0 1.0)))
                                    (* (* (- alpha) alpha) (log (- 1.0 u0))))