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

Average Error: 3.8 → 1.8

Time: 8.8s

Precision: binary64

Math

\[\frac{x}{x + y \cdot e^{2 \cdot \left(\frac{z \cdot \sqrt{t + a}}{t} - \left(b - c\right) \cdot \left(\left(a + \frac{5}{6}\right) - \frac{2}{t \cdot 3}\right)\right)}} \]

↓

\[\begin{array}{l} t_1 := \left(a + 0.8333333333333334\right) - \frac{0.6666666666666666}{t}\\ \mathbf{if}\;t \leq 3.04319920050061 \cdot 10^{-301}:\\ \;\;\;\;\frac{x}{\mathsf{fma}\left(y, {\left(e^{2}\right)}^{\left(\mathsf{fma}\left(t_1, c - b, \frac{z \cdot \sqrt{a}}{t}\right)\right)}, x\right)}\\ \mathbf{else}:\\ \;\;\;\;\frac{x}{\mathsf{fma}\left(y, {\left(e^{2}\right)}^{\left(\mathsf{fma}\left(t_1, c - b, z \cdot \sqrt{\frac{1}{t}}\right)\right)}, x\right)}\\ \end{array} \]

FPCore

(FPCore (x y z t a b c)
 :precision binary64
 (/
  x
  (+
   x
   (*
    y
    (exp
     (*
      2.0
      (-
       (/ (* z (sqrt (+ t a))) t)
       (* (- b c) (- (+ a (/ 5.0 6.0)) (/ 2.0 (* t 3.0)))))))))))

↓

(FPCore (x y z t a b c)
 :precision binary64
 (let* ((t_1 (- (+ a 0.8333333333333334) (/ 0.6666666666666666 t))))
   (if (<= t 3.04319920050061e-301)
     (/ x (fma y (pow (exp 2.0) (fma t_1 (- c b) (/ (* z (sqrt a)) t))) x))
     (/
      x
      (fma y (pow (exp 2.0) (fma t_1 (- c b) (* z (sqrt (/ 1.0 t))))) x)))))

C

double code(double x, double y, double z, double t, double a, double b, double c) {
	return x / (x + (y * exp((2.0 * (((z * sqrt((t + a))) / t) - ((b - c) * ((a + (5.0 / 6.0)) - (2.0 / (t * 3.0)))))))));
}

↓

double code(double x, double y, double z, double t, double a, double b, double c) {
	double t_1 = (a + 0.8333333333333334) - (0.6666666666666666 / t);
	double tmp;
	if (t <= 3.04319920050061e-301) {
		tmp = x / fma(y, pow(exp(2.0), fma(t_1, (c - b), ((z * sqrt(a)) / t))), x);
	} else {
		tmp = x / fma(y, pow(exp(2.0), fma(t_1, (c - b), (z * sqrt((1.0 / t))))), x);
	}
	return tmp;
}

Julia

function code(x, y, z, t, a, b, c)
	return Float64(x / Float64(x + Float64(y * exp(Float64(2.0 * Float64(Float64(Float64(z * sqrt(Float64(t + a))) / t) - Float64(Float64(b - c) * Float64(Float64(a + Float64(5.0 / 6.0)) - Float64(2.0 / Float64(t * 3.0))))))))))
end

↓

function code(x, y, z, t, a, b, c)
	t_1 = Float64(Float64(a + 0.8333333333333334) - Float64(0.6666666666666666 / t))
	tmp = 0.0
	if (t <= 3.04319920050061e-301)
		tmp = Float64(x / fma(y, (exp(2.0) ^ fma(t_1, Float64(c - b), Float64(Float64(z * sqrt(a)) / t))), x));
	else
		tmp = Float64(x / fma(y, (exp(2.0) ^ fma(t_1, Float64(c - b), Float64(z * sqrt(Float64(1.0 / t))))), x));
	end
	return tmp
end

Wolfram

code[x_, y_, z_, t_, a_, b_, c_] := N[(x / N[(x + N[(y * N[Exp[N[(2.0 * N[(N[(N[(z * N[Sqrt[N[(t + a), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / t), $MachinePrecision] - N[(N[(b - c), $MachinePrecision] * N[(N[(a + N[(5.0 / 6.0), $MachinePrecision]), $MachinePrecision] - N[(2.0 / N[(t * 3.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]

↓

code[x_, y_, z_, t_, a_, b_, c_] := Block[{t$95$1 = N[(N[(a + 0.8333333333333334), $MachinePrecision] - N[(0.6666666666666666 / t), $MachinePrecision]), $MachinePrecision]}, If[LessEqual[t, 3.04319920050061e-301], N[(x / N[(y * N[Power[N[Exp[2.0], $MachinePrecision], N[(t$95$1 * N[(c - b), $MachinePrecision] + N[(N[(z * N[Sqrt[a], $MachinePrecision]), $MachinePrecision] / t), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] + x), $MachinePrecision]), $MachinePrecision], N[(x / N[(y * N[Power[N[Exp[2.0], $MachinePrecision], N[(t$95$1 * N[(c - b), $MachinePrecision] + N[(z * N[Sqrt[N[(1.0 / t), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] + x), $MachinePrecision]), $MachinePrecision]]]

Error

Bits error versus x

Bits error versus y

Bits error versus z

Bits error versus t

Bits error versus a

Bits error versus b

Bits error versus c

Target

Original	3.8
Target	3.2
Herbie	1.8

\[\begin{array}{l} \mathbf{if}\;t < -2.118326644891581 \cdot 10^{-50}:\\ \;\;\;\;\frac{x}{x + y \cdot e^{2 \cdot \left(\left(a \cdot c + 0.8333333333333334 \cdot c\right) - a \cdot b\right)}}\\ \mathbf{elif}\;t < 5.196588770651547 \cdot 10^{-123}:\\ \;\;\;\;\frac{x}{x + y \cdot e^{2 \cdot \frac{\left(z \cdot \sqrt{t + a}\right) \cdot \left(\left(3 \cdot t\right) \cdot \left(a - \frac{5}{6}\right)\right) - \left(\left(\frac{5}{6} + a\right) \cdot \left(3 \cdot t\right) - 2\right) \cdot \left(\left(a - \frac{5}{6}\right) \cdot \left(\left(b - c\right) \cdot t\right)\right)}{\left(\left(t \cdot t\right) \cdot 3\right) \cdot \left(a - \frac{5}{6}\right)}}}\\ \mathbf{else}:\\ \;\;\;\;\frac{x}{x + y \cdot e^{2 \cdot \left(\frac{z \cdot \sqrt{t + a}}{t} - \left(b - c\right) \cdot \left(\left(a + \frac{5}{6}\right) - \frac{2}{t \cdot 3}\right)\right)}}\\ \end{array} \]

Derivation

1. Split input into 2 regimes

2. if t < 3.04319920050060997e-301

   1. Initial program 5.9

      \[\frac{x}{x + y \cdot e^{2 \cdot \left(\frac{z \cdot \sqrt{t + a}}{t} - \left(b - c\right) \cdot \left(\left(a + \frac{5}{6}\right) - \frac{2}{t \cdot 3}\right)\right)}} \]

   2. Simplified 3.5

      \[\leadsto \color{blue}{\frac{x}{\mathsf{fma}\left(y, {\left(e^{2}\right)}^{\left(\mathsf{fma}\left(\left(a + 0.8333333333333334\right) - \frac{0.6666666666666666}{t}, c - b, \frac{z \cdot \sqrt{t + a}}{t}\right)\right)}, x\right)}} \]

   3. Taylor expanded in t around 0 3.5

      \[\leadsto \frac{x}{\mathsf{fma}\left(y, {\left(e^{2}\right)}^{\left(\mathsf{fma}\left(\left(a + 0.8333333333333334\right) - \frac{0.6666666666666666}{t}, c - b, \frac{\color{blue}{\sqrt{a} \cdot z}}{t}\right)\right)}, x\right)} \]

   4. Simplified 3.5

      \[\leadsto \frac{x}{\mathsf{fma}\left(y, {\left(e^{2}\right)}^{\left(\mathsf{fma}\left(\left(a + 0.8333333333333334\right) - \frac{0.6666666666666666}{t}, c - b, \frac{\color{blue}{z \cdot \sqrt{a}}}{t}\right)\right)}, x\right)} \]

   if 3.04319920050060997e-301 < t

   1. Initial program 3.1

      \[\frac{x}{x + y \cdot e^{2 \cdot \left(\frac{z \cdot \sqrt{t + a}}{t} - \left(b - c\right) \cdot \left(\left(a + \frac{5}{6}\right) - \frac{2}{t \cdot 3}\right)\right)}} \]

   2. Simplified 2.2

      \[\leadsto \color{blue}{\frac{x}{\mathsf{fma}\left(y, {\left(e^{2}\right)}^{\left(\mathsf{fma}\left(\left(a + 0.8333333333333334\right) - \frac{0.6666666666666666}{t}, c - b, \frac{z \cdot \sqrt{t + a}}{t}\right)\right)}, x\right)}} \]

   3. Taylor expanded in a around 0 1.2

      \[\leadsto \frac{x}{\mathsf{fma}\left(y, {\left(e^{2}\right)}^{\left(\mathsf{fma}\left(\left(a + 0.8333333333333334\right) - \frac{0.6666666666666666}{t}, c - b, \color{blue}{\sqrt{\frac{1}{t}} \cdot z}\right)\right)}, x\right)} \]
3. Recombined 2 regimes into one program.

4. Final simplification 1.8

   \[\leadsto \begin{array}{l} \mathbf{if}\;t \leq 3.04319920050061 \cdot 10^{-301}:\\ \;\;\;\;\frac{x}{\mathsf{fma}\left(y, {\left(e^{2}\right)}^{\left(\mathsf{fma}\left(\left(a + 0.8333333333333334\right) - \frac{0.6666666666666666}{t}, c - b, \frac{z \cdot \sqrt{a}}{t}\right)\right)}, x\right)}\\ \mathbf{else}:\\ \;\;\;\;\frac{x}{\mathsf{fma}\left(y, {\left(e^{2}\right)}^{\left(\mathsf{fma}\left(\left(a + 0.8333333333333334\right) - \frac{0.6666666666666666}{t}, c - b, z \cdot \sqrt{\frac{1}{t}}\right)\right)}, x\right)}\\ \end{array} \]

Reproduce

herbie shell --seed 2022131 
(FPCore (x y z t a b c)
  :name "Numeric.SpecFunctions:invIncompleteBetaWorker from math-functions-0.1.5.2, I"
  :precision binary64

  :herbie-target
  (if (< t -2.118326644891581e-50) (/ x (+ x (* y (exp (* 2.0 (- (+ (* a c) (* 0.8333333333333334 c)) (* a b))))))) (if (< t 5.196588770651547e-123) (/ x (+ x (* y (exp (* 2.0 (/ (- (* (* z (sqrt (+ t a))) (* (* 3.0 t) (- a (/ 5.0 6.0)))) (* (- (* (+ (/ 5.0 6.0) a) (* 3.0 t)) 2.0) (* (- a (/ 5.0 6.0)) (* (- b c) t)))) (* (* (* t t) 3.0) (- a (/ 5.0 6.0))))))))) (/ x (+ x (* y (exp (* 2.0 (- (/ (* z (sqrt (+ t a))) t) (* (- b c) (- (+ a (/ 5.0 6.0)) (/ 2.0 (* t 3.0))))))))))))

  (/ x (+ x (* y (exp (* 2.0 (- (/ (* z (sqrt (+ t a))) t) (* (- b c) (- (+ a (/ 5.0 6.0)) (/ 2.0 (* t 3.0)))))))))))