Rump's expression from Stadtherr's award speech

Percentage Accurate: 9.2% → 20.2%
Time: 6.7s
Alternatives: 2
Speedup: 44.0×

Specification

?
\[x = 77617 \land y = 33096\]
\[\begin{array}{l} \\ -0.8273960599468214 \end{array} \]
(FPCore (x y) :precision binary64 -0.8273960599468214)
double code(double x, double y) {
	return -0.8273960599468214;
}
real(8) function code(x, y)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    code = -0.8273960599468214d0
end function
public static double code(double x, double y) {
	return -0.8273960599468214;
}
def code(x, y):
	return -0.8273960599468214
function code(x, y)
	return -0.8273960599468214
end
function tmp = code(x, y)
	tmp = -0.8273960599468214;
end
code[x_, y_] := -0.8273960599468214
\begin{array}{l}

\\
-0.8273960599468214
\end{array}

Sampling outcomes in binary64 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 2 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: 9.2% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \left(\left(333.75 \cdot {y}^{6} + \left(x \cdot x\right) \cdot \left(\left(\left(\left(\left(\left(11 \cdot x\right) \cdot x\right) \cdot y\right) \cdot y - {y}^{6}\right) - 121 \cdot {y}^{4}\right) - 2\right)\right) + 5.5 \cdot {y}^{8}\right) + \frac{x}{2 \cdot y} \end{array} \]
(FPCore (x y)
 :precision binary64
 (+
  (+
   (+
    (* 333.75 (pow y 6.0))
    (*
     (* x x)
     (-
      (- (- (* (* (* (* 11.0 x) x) y) y) (pow y 6.0)) (* 121.0 (pow y 4.0)))
      2.0)))
   (* 5.5 (pow y 8.0)))
  (/ x (* 2.0 y))))
double code(double x, double y) {
	return (((333.75 * pow(y, 6.0)) + ((x * x) * (((((((11.0 * x) * x) * y) * y) - pow(y, 6.0)) - (121.0 * pow(y, 4.0))) - 2.0))) + (5.5 * pow(y, 8.0))) + (x / (2.0 * y));
}
real(8) function code(x, y)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    code = (((333.75d0 * (y ** 6.0d0)) + ((x * x) * (((((((11.0d0 * x) * x) * y) * y) - (y ** 6.0d0)) - (121.0d0 * (y ** 4.0d0))) - 2.0d0))) + (5.5d0 * (y ** 8.0d0))) + (x / (2.0d0 * y))
end function
public static double code(double x, double y) {
	return (((333.75 * Math.pow(y, 6.0)) + ((x * x) * (((((((11.0 * x) * x) * y) * y) - Math.pow(y, 6.0)) - (121.0 * Math.pow(y, 4.0))) - 2.0))) + (5.5 * Math.pow(y, 8.0))) + (x / (2.0 * y));
}
def code(x, y):
	return (((333.75 * math.pow(y, 6.0)) + ((x * x) * (((((((11.0 * x) * x) * y) * y) - math.pow(y, 6.0)) - (121.0 * math.pow(y, 4.0))) - 2.0))) + (5.5 * math.pow(y, 8.0))) + (x / (2.0 * y))
function code(x, y)
	return Float64(Float64(Float64(Float64(333.75 * (y ^ 6.0)) + Float64(Float64(x * x) * Float64(Float64(Float64(Float64(Float64(Float64(Float64(11.0 * x) * x) * y) * y) - (y ^ 6.0)) - Float64(121.0 * (y ^ 4.0))) - 2.0))) + Float64(5.5 * (y ^ 8.0))) + Float64(x / Float64(2.0 * y)))
end
function tmp = code(x, y)
	tmp = (((333.75 * (y ^ 6.0)) + ((x * x) * (((((((11.0 * x) * x) * y) * y) - (y ^ 6.0)) - (121.0 * (y ^ 4.0))) - 2.0))) + (5.5 * (y ^ 8.0))) + (x / (2.0 * y));
end
code[x_, y_] := N[(N[(N[(N[(333.75 * N[Power[y, 6.0], $MachinePrecision]), $MachinePrecision] + N[(N[(x * x), $MachinePrecision] * N[(N[(N[(N[(N[(N[(N[(11.0 * x), $MachinePrecision] * x), $MachinePrecision] * y), $MachinePrecision] * y), $MachinePrecision] - N[Power[y, 6.0], $MachinePrecision]), $MachinePrecision] - N[(121.0 * N[Power[y, 4.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] - 2.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(5.5 * N[Power[y, 8.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] + N[(x / N[(2.0 * y), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
\left(\left(333.75 \cdot {y}^{6} + \left(x \cdot x\right) \cdot \left(\left(\left(\left(\left(\left(11 \cdot x\right) \cdot x\right) \cdot y\right) \cdot y - {y}^{6}\right) - 121 \cdot {y}^{4}\right) - 2\right)\right) + 5.5 \cdot {y}^{8}\right) + \frac{x}{2 \cdot y}
\end{array}

Alternative 1: 20.2% accurate, 28.5× speedup?

\[\begin{array}{l} \\ \frac{x \cdot -0.5}{y} \end{array} \]
(FPCore (x y) :precision binary64 (/ (* x -0.5) y))
double code(double x, double y) {
	return (x * -0.5) / y;
}
real(8) function code(x, y)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    code = (x * (-0.5d0)) / y
end function
public static double code(double x, double y) {
	return (x * -0.5) / y;
}
def code(x, y):
	return (x * -0.5) / y
function code(x, y)
	return Float64(Float64(x * -0.5) / y)
end
function tmp = code(x, y)
	tmp = (x * -0.5) / y;
end
code[x_, y_] := N[(N[(x * -0.5), $MachinePrecision] / y), $MachinePrecision]
\begin{array}{l}

\\
\frac{x \cdot -0.5}{y}
\end{array}
Derivation
  1. Initial program 9.2%

    \[\left(\left(333.75 \cdot {y}^{6} + \left(x \cdot x\right) \cdot \left(\left(\left(\left(\left(\left(11 \cdot x\right) \cdot x\right) \cdot y\right) \cdot y - {y}^{6}\right) - 121 \cdot {y}^{4}\right) - 2\right)\right) + 5.5 \cdot {y}^{8}\right) + \frac{x}{2 \cdot y} \]
  2. Add Preprocessing
  3. Taylor expanded in y around 0

    \[\leadsto \color{blue}{-2 \cdot {x}^{2}} + \frac{x}{2 \cdot y} \]
  4. Step-by-step derivation
    1. lower-*.f64N/A

      \[\leadsto \color{blue}{-2 \cdot {x}^{2}} + \frac{x}{2 \cdot y} \]
    2. unpow2N/A

      \[\leadsto -2 \cdot \color{blue}{\left(x \cdot x\right)} + \frac{x}{2 \cdot y} \]
    3. lower-*.f6410.8

      \[\leadsto -2 \cdot \color{blue}{\left(x \cdot x\right)} + \frac{x}{2 \cdot y} \]
  5. Applied rewrites10.8%

    \[\leadsto \color{blue}{-2 \cdot \left(x \cdot x\right)} + \frac{x}{2 \cdot y} \]
  6. Applied rewrites10.8%

    \[\leadsto \color{blue}{\frac{\mathsf{fma}\left(\left(\left(x \cdot x\right) \cdot \left(x \cdot \left(x \cdot \left(x \cdot x\right)\right)\right)\right) \cdot \left(x \cdot \left(x \cdot x\right)\right), \left(\left(\left(x \cdot x\right) \cdot \left(x \cdot \left(x \cdot \left(x \cdot x\right)\right)\right)\right) \cdot \left(x \cdot \left(x \cdot x\right)\right)\right) \cdot -512, \frac{\left(\left(x \cdot x\right) \cdot \left(x \cdot \left(x \cdot \left(x \cdot x\right)\right)\right)\right) \cdot \left(x \cdot \left(x \cdot x\right)\right)}{-512 \cdot \left(\left(y \cdot \left(y \cdot y\right)\right) \cdot \left(\left(y \cdot \left(y \cdot y\right)\right) \cdot \left(y \cdot \left(y \cdot y\right)\right)\right)\right)}\right) \cdot \frac{1}{\mathsf{fma}\left(x \cdot x, \left(x \cdot x\right) \cdot 4 - \frac{x}{-y}, \frac{x \cdot x}{\left(y \cdot y\right) \cdot 4}\right)}}{\mathsf{fma}\left(\frac{x \cdot \left(x \cdot x\right)}{-8 \cdot \left(y \cdot \left(y \cdot y\right)\right)}, \frac{x \cdot \left(x \cdot x\right)}{-8 \cdot \left(y \cdot \left(y \cdot y\right)\right)} - -8 \cdot \left(\left(x \cdot x\right) \cdot \left(x \cdot \left(x \cdot \left(x \cdot x\right)\right)\right)\right), \left(\left(x \cdot x\right) \cdot \left(x \cdot \left(x \cdot \left(x \cdot x\right)\right)\right)\right) \cdot \left(\left(\left(x \cdot x\right) \cdot \left(x \cdot \left(x \cdot \left(x \cdot x\right)\right)\right)\right) \cdot 64\right)\right)}} \]
  7. Taylor expanded in x around 0

    \[\leadsto \color{blue}{\frac{-1}{2} \cdot \frac{x}{y}} \]
  8. Step-by-step derivation
    1. associate-*r/N/A

      \[\leadsto \color{blue}{\frac{\frac{-1}{2} \cdot x}{y}} \]
    2. lower-/.f64N/A

      \[\leadsto \color{blue}{\frac{\frac{-1}{2} \cdot x}{y}} \]
    3. *-commutativeN/A

      \[\leadsto \frac{\color{blue}{x \cdot \frac{-1}{2}}}{y} \]
    4. lower-*.f6420.2

      \[\leadsto \frac{\color{blue}{x \cdot -0.5}}{y} \]
  9. Applied rewrites20.2%

    \[\leadsto \color{blue}{\frac{x \cdot -0.5}{y}} \]
  10. Add Preprocessing

Alternative 2: 10.8% accurate, 44.0× speedup?

\[\begin{array}{l} \\ x \cdot \left(x \cdot -2\right) \end{array} \]
(FPCore (x y) :precision binary64 (* x (* x -2.0)))
double code(double x, double y) {
	return x * (x * -2.0);
}
real(8) function code(x, y)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    code = x * (x * (-2.0d0))
end function
public static double code(double x, double y) {
	return x * (x * -2.0);
}
def code(x, y):
	return x * (x * -2.0)
function code(x, y)
	return Float64(x * Float64(x * -2.0))
end
function tmp = code(x, y)
	tmp = x * (x * -2.0);
end
code[x_, y_] := N[(x * N[(x * -2.0), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
x \cdot \left(x \cdot -2\right)
\end{array}
Derivation
  1. Initial program 9.2%

    \[\left(\left(333.75 \cdot {y}^{6} + \left(x \cdot x\right) \cdot \left(\left(\left(\left(\left(\left(11 \cdot x\right) \cdot x\right) \cdot y\right) \cdot y - {y}^{6}\right) - 121 \cdot {y}^{4}\right) - 2\right)\right) + 5.5 \cdot {y}^{8}\right) + \frac{x}{2 \cdot y} \]
  2. Add Preprocessing
  3. Taylor expanded in y around 0

    \[\leadsto \color{blue}{-2 \cdot {x}^{2}} + \frac{x}{2 \cdot y} \]
  4. Step-by-step derivation
    1. lower-*.f64N/A

      \[\leadsto \color{blue}{-2 \cdot {x}^{2}} + \frac{x}{2 \cdot y} \]
    2. unpow2N/A

      \[\leadsto -2 \cdot \color{blue}{\left(x \cdot x\right)} + \frac{x}{2 \cdot y} \]
    3. lower-*.f6410.8

      \[\leadsto -2 \cdot \color{blue}{\left(x \cdot x\right)} + \frac{x}{2 \cdot y} \]
  5. Applied rewrites10.8%

    \[\leadsto \color{blue}{-2 \cdot \left(x \cdot x\right)} + \frac{x}{2 \cdot y} \]
  6. Taylor expanded in x around inf

    \[\leadsto \color{blue}{-2 \cdot {x}^{2}} \]
  7. Step-by-step derivation
    1. unpow2N/A

      \[\leadsto -2 \cdot \color{blue}{\left(x \cdot x\right)} \]
    2. associate-*r*N/A

      \[\leadsto \color{blue}{\left(-2 \cdot x\right) \cdot x} \]
    3. *-commutativeN/A

      \[\leadsto \color{blue}{x \cdot \left(-2 \cdot x\right)} \]
    4. lower-*.f64N/A

      \[\leadsto \color{blue}{x \cdot \left(-2 \cdot x\right)} \]
    5. *-commutativeN/A

      \[\leadsto x \cdot \color{blue}{\left(x \cdot -2\right)} \]
    6. lower-*.f6410.8

      \[\leadsto x \cdot \color{blue}{\left(x \cdot -2\right)} \]
  8. Applied rewrites10.8%

    \[\leadsto \color{blue}{x \cdot \left(x \cdot -2\right)} \]
  9. Add Preprocessing

Reproduce

?
herbie shell --seed 2024221 
(FPCore (x y)
  :name "Rump's expression from Stadtherr's award speech"
  :precision binary64
  :pre (and (== x 77617.0) (== y 33096.0))
  (+ (+ (+ (* 333.75 (pow y 6.0)) (* (* x x) (- (- (- (* (* (* (* 11.0 x) x) y) y) (pow y 6.0)) (* 121.0 (pow y 4.0))) 2.0))) (* 5.5 (pow y 8.0))) (/ x (* 2.0 y))))