Average Error: 18.1 → 0.1
Time: 4.9s
Precision: binary64
\[\]
↓
\[\]
↓
double code(double x, double y) {
	return ((double) (1.0 - ((double) log(((double) (1.0 - ((double) (((double) (x - y)) / ((double) (1.0 - y))))))))));
}

↓
double code(double x, double y) {
	double VAR;
	if ((((double) (((double) (x - y)) / ((double) (1.0 - y)))) <= 0.9999999547197751)) {
		VAR = ((double) (1.0 - ((double) (((double) log(((double) sqrt(((double) (1.0 - ((double) (((double) (x - y)) / ((double) (1.0 - y)))))))))) + ((double) log(((double) sqrt(((double) (1.0 - ((double) (((double) (x - y)) / ((double) (1.0 - y))))))))))))));
	} else {
		VAR = ((double) (1.0 - ((double) log(((double) (((double) (x / y)) + ((double) (((double) (1.0 / y)) * ((double) (((double) (x / y)) - 1.0))))))))));
	}
	return VAR;
}

Error
Bits error versus x
Bits error versus y
Try it out
Your Program's Arguments
Results
Enter valid numbers for all inputs
Target
Original18.1
Target0.1
Herbie0.1
\[\]
Derivation
  1. Split input into 2 regimes
  2. if  (/ (- x y) (- 1.0 y))  < 0.9999999547197751
    1. Initial program 0.1
      \[\]
    2. Using strategy rm
    3. Applied add-sqr-sqrt0.1
      \[\leadsto \]
    4. Applied log-prod0.1
      \[\leadsto \]
    if 0.9999999547197751 <  (/ (- x y) (- 1.0 y)) 
    1. Initial program 62.8
      \[\]
    2. Taylor expanded around inf 0.2
      \[\leadsto \]
    3. Simplified0.2
      \[\leadsto \]
  3. Recombined 2 regimes into one program.
  4. Final simplification0.1
    \[\leadsto \]
Reproduce
herbie shell --seed 2020180 
(FPCore (x y)
  :name "Numeric.SpecFunctions:invIncompleteGamma from math-functions-0.1.5.2, B"
  :precision binary64

  :herbie-target
  (if (< y -81284752.61947241) (- 1.0 (log (- (/ x (* y y)) (- (/ 1.0 y) (/ x y))))) (if (< y 3.0094271212461764e+25) (log (/ (exp 1.0) (- 1.0 (/ (- x y) (- 1.0 y))))) (- 1.0 (log (- (/ x (* y y)) (- (/ 1.0 y) (/ x y)))))))

  (- 1.0 (log (- 1.0 (/ (- x y) (- 1.0 y))))))