Numeric.SpecFunctions:invIncompleteBetaWorker from math-functions-0.1.5.2, G

Average Error: 5.6 → 0.9

Time: 1.2min

Precision: binary64

Cost: 19840

Math

\[x + \frac{e^{y \cdot \log \left(\frac{y}{z + y}\right)}}{y} \]

↓

\[x + \frac{{\left(e^{y}\right)}^{\log \left(\frac{y}{z + y}\right)}}{y} \]

FPCore

(FPCore (x y z)
 :precision binary64
 (+ x (/ (exp (* y (log (/ y (+ z y))))) y)))

↓

(FPCore (x y z)
 :precision binary64
 (+ x (/ (pow (exp y) (log (/ y (+ z y)))) y)))

C

double code(double x, double y, double z) {
	return x + (exp((y * log((y / (z + y))))) / y);
}

↓

double code(double x, double y, double z) {
	return x + (pow(exp(y), log((y / (z + y)))) / y);
}

Fortran

real(8) function code(x, y, z)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    code = x + (exp((y * log((y / (z + y))))) / y)
end function

↓

real(8) function code(x, y, z)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    code = x + ((exp(y) ** log((y / (z + y)))) / y)
end function

Java

public static double code(double x, double y, double z) {
	return x + (Math.exp((y * Math.log((y / (z + y))))) / y);
}

↓

public static double code(double x, double y, double z) {
	return x + (Math.pow(Math.exp(y), Math.log((y / (z + y)))) / y);
}

Python

def code(x, y, z):
	return x + (math.exp((y * math.log((y / (z + y))))) / y)

↓

def code(x, y, z):
	return x + (math.pow(math.exp(y), math.log((y / (z + y)))) / y)

Julia

function code(x, y, z)
	return Float64(x + Float64(exp(Float64(y * log(Float64(y / Float64(z + y))))) / y))
end

↓

function code(x, y, z)
	return Float64(x + Float64((exp(y) ^ log(Float64(y / Float64(z + y)))) / y))
end

MATLAB

function tmp = code(x, y, z)
	tmp = x + (exp((y * log((y / (z + y))))) / y);
end

↓

function tmp = code(x, y, z)
	tmp = x + ((exp(y) ^ log((y / (z + y)))) / y);
end

Wolfram

code[x_, y_, z_] := N[(x + N[(N[Exp[N[(y * N[Log[N[(y / N[(z + y), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]], $MachinePrecision] / y), $MachinePrecision]), $MachinePrecision]

↓

code[x_, y_, z_] := N[(x + N[(N[Power[N[Exp[y], $MachinePrecision], N[Log[N[(y / N[(z + y), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision] / y), $MachinePrecision]), $MachinePrecision]

Target

Original	5.6
Target	0.9
Herbie	0.9

\[\begin{array}{l} \mathbf{if}\;\frac{y}{z + y} < 7.11541576 \cdot 10^{-315}:\\ \;\;\;\;x + \frac{e^{\frac{-1}{z}}}{y}\\ \mathbf{else}:\\ \;\;\;\;x + \frac{e^{\log \left({\left(\frac{y}{y + z}\right)}^{y}\right)}}{y}\\ \end{array} \]

Derivation

1. Initial program 5.6

   \[x + \frac{e^{y \cdot \log \left(\frac{y}{z + y}\right)}}{y} \]

2. Simplified 0.9

   \[\leadsto \color{blue}{x + \frac{{\left(e^{y}\right)}^{\log \left(\frac{y}{z + y}\right)}}{y}} \]
   Proof

Alternatives

Alternative 1
Error	18.0
Cost	720

\[\begin{array}{l} \mathbf{if}\;x \leq -1.1 \cdot 10^{+56}:\\ \;\;\;\;x\\ \mathbf{elif}\;x \leq -14600000000000:\\ \;\;\;\;\frac{1}{y}\\ \mathbf{elif}\;x \leq -1.1 \cdot 10^{-77}:\\ \;\;\;\;x\\ \mathbf{elif}\;x \leq 115:\\ \;\;\;\;\frac{1}{y}\\ \mathbf{else}:\\ \;\;\;\;x\\ \end{array} \]

Alternative 2
Error	2.2
Cost	320

\[\frac{1}{y} + x \]

Alternative 3
Error	27.7
Cost	64

\[x \]

Reproduce

herbie shell --seed 2023033 
(FPCore (x y z)
  :name "Numeric.SpecFunctions:invIncompleteBetaWorker from math-functions-0.1.5.2, G"
  :precision binary64

  :herbie-target
  (if (< (/ y (+ z y)) 7.11541576e-315) (+ x (/ (exp (/ -1.0 z)) y)) (+ x (/ (exp (log (pow (/ y (+ y z)) y))) y)))

  (+ x (/ (exp (* y (log (/ y (+ z y))))) y)))