Octave 3.8, oct_fill_randg

Average Accuracy: 99.8% → 99.8%

Time: 10.8s

Precision: binary64

Cost: 13504

Math

\[\left(a - \frac{1}{3}\right) \cdot \left(1 + \frac{1}{\sqrt{9 \cdot \left(a - \frac{1}{3}\right)}} \cdot rand\right) \]

↓

\[\left(a + -0.3333333333333333\right) \cdot \left(1 + \frac{rand}{\sqrt{\mathsf{fma}\left(a, 9, -3\right)}}\right) \]

FPCore

(FPCore (a rand)
 :precision binary64
 (*
  (- a (/ 1.0 3.0))
  (+ 1.0 (* (/ 1.0 (sqrt (* 9.0 (- a (/ 1.0 3.0))))) rand))))

↓

(FPCore (a rand)
 :precision binary64
 (* (+ a -0.3333333333333333) (+ 1.0 (/ rand (sqrt (fma a 9.0 -3.0))))))

C

double code(double a, double rand) {
	return (a - (1.0 / 3.0)) * (1.0 + ((1.0 / sqrt((9.0 * (a - (1.0 / 3.0))))) * rand));
}

↓

double code(double a, double rand) {
	return (a + -0.3333333333333333) * (1.0 + (rand / sqrt(fma(a, 9.0, -3.0))));
}

Julia

function code(a, rand)
	return Float64(Float64(a - Float64(1.0 / 3.0)) * Float64(1.0 + Float64(Float64(1.0 / sqrt(Float64(9.0 * Float64(a - Float64(1.0 / 3.0))))) * rand)))
end

↓

function code(a, rand)
	return Float64(Float64(a + -0.3333333333333333) * Float64(1.0 + Float64(rand / sqrt(fma(a, 9.0, -3.0)))))
end

Wolfram

code[a_, rand_] := N[(N[(a - N[(1.0 / 3.0), $MachinePrecision]), $MachinePrecision] * N[(1.0 + N[(N[(1.0 / N[Sqrt[N[(9.0 * N[(a - N[(1.0 / 3.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * rand), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]

↓

code[a_, rand_] := N[(N[(a + -0.3333333333333333), $MachinePrecision] * N[(1.0 + N[(rand / N[Sqrt[N[(a * 9.0 + -3.0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]

Derivation

1. Initial program 99.8%

   \[\left(a - \frac{1}{3}\right) \cdot \left(1 + \frac{1}{\sqrt{9 \cdot \left(a - \frac{1}{3}\right)}} \cdot rand\right) \]

2. Simplified 99.8%

   \[\leadsto \color{blue}{\left(a + -0.3333333333333333\right) \cdot \left(1 + \frac{rand}{\sqrt{\mathsf{fma}\left(a, 9, -3\right)}}\right)} \]
   Proof

   [Start] 99.8	\[ \left(a - \frac{1}{3}\right) \cdot \left(1 + \frac{1}{\sqrt{9 \cdot \left(a - \frac{1}{3}\right)}} \cdot rand\right) \]
   remove-double-neg [<=] 99.8	\[ \color{blue}{\left(-\left(-\left(a - \frac{1}{3}\right)\right)\right)} \cdot \left(1 + \frac{1}{\sqrt{9 \cdot \left(a - \frac{1}{3}\right)}} \cdot rand\right) \]
   remove-double-neg [=>] 99.8	\[ \color{blue}{\left(a - \frac{1}{3}\right)} \cdot \left(1 + \frac{1}{\sqrt{9 \cdot \left(a - \frac{1}{3}\right)}} \cdot rand\right) \]
   sub-neg [=>] 99.8	\[ \color{blue}{\left(a + \left(-\frac{1}{3}\right)\right)} \cdot \left(1 + \frac{1}{\sqrt{9 \cdot \left(a - \frac{1}{3}\right)}} \cdot rand\right) \]
   metadata-eval [=>] 99.8	\[ \left(a + \left(-\color{blue}{0.3333333333333333}\right)\right) \cdot \left(1 + \frac{1}{\sqrt{9 \cdot \left(a - \frac{1}{3}\right)}} \cdot rand\right) \]
   metadata-eval [=>] 99.8	\[ \left(a + \color{blue}{-0.3333333333333333}\right) \cdot \left(1 + \frac{1}{\sqrt{9 \cdot \left(a - \frac{1}{3}\right)}} \cdot rand\right) \]
   remove-double-neg [<=] 99.8	\[ \left(a + -0.3333333333333333\right) \cdot \left(1 + \color{blue}{\left(-\left(-\frac{1}{\sqrt{9 \cdot \left(a - \frac{1}{3}\right)}} \cdot rand\right)\right)}\right) \]
   remove-double-neg [=>] 99.8	\[ \left(a + -0.3333333333333333\right) \cdot \left(1 + \color{blue}{\frac{1}{\sqrt{9 \cdot \left(a - \frac{1}{3}\right)}} \cdot rand}\right) \]
   associate-*l/ [=>] 99.8	\[ \left(a + -0.3333333333333333\right) \cdot \left(1 + \color{blue}{\frac{1 \cdot rand}{\sqrt{9 \cdot \left(a - \frac{1}{3}\right)}}}\right) \]
   *-lft-identity [=>] 99.8	\[ \left(a + -0.3333333333333333\right) \cdot \left(1 + \frac{\color{blue}{rand}}{\sqrt{9 \cdot \left(a - \frac{1}{3}\right)}}\right) \]
   sub-neg [=>] 99.8	\[ \left(a + -0.3333333333333333\right) \cdot \left(1 + \frac{rand}{\sqrt{9 \cdot \color{blue}{\left(a + \left(-\frac{1}{3}\right)\right)}}}\right) \]
   distribute-lft-in [=>] 99.8	\[ \left(a + -0.3333333333333333\right) \cdot \left(1 + \frac{rand}{\sqrt{\color{blue}{9 \cdot a + 9 \cdot \left(-\frac{1}{3}\right)}}}\right) \]
   *-commutative [<=] 99.8	\[ \left(a + -0.3333333333333333\right) \cdot \left(1 + \frac{rand}{\sqrt{\color{blue}{a \cdot 9} + 9 \cdot \left(-\frac{1}{3}\right)}}\right) \]
   fma-def [=>] 99.8	\[ \left(a + -0.3333333333333333\right) \cdot \left(1 + \frac{rand}{\sqrt{\color{blue}{\mathsf{fma}\left(a, 9, 9 \cdot \left(-\frac{1}{3}\right)\right)}}}\right) \]
   metadata-eval [=>] 99.8	\[ \left(a + -0.3333333333333333\right) \cdot \left(1 + \frac{rand}{\sqrt{\mathsf{fma}\left(a, 9, 9 \cdot \left(-\color{blue}{0.3333333333333333}\right)\right)}}\right) \]
   metadata-eval [=>] 99.8	\[ \left(a + -0.3333333333333333\right) \cdot \left(1 + \frac{rand}{\sqrt{\mathsf{fma}\left(a, 9, 9 \cdot \color{blue}{-0.3333333333333333}\right)}}\right) \]
   metadata-eval [=>] 99.8	\[ \left(a + -0.3333333333333333\right) \cdot \left(1 + \frac{rand}{\sqrt{\mathsf{fma}\left(a, 9, \color{blue}{-3}\right)}}\right) \]

3. Final simplification 99.8%

   \[\leadsto \left(a + -0.3333333333333333\right) \cdot \left(1 + \frac{rand}{\sqrt{\mathsf{fma}\left(a, 9, -3\right)}}\right) \]

Alternatives

Alternative 1
Accuracy	99.8%
Cost	7232

\[\left(a + -0.3333333333333333\right) \cdot \left(1 + \frac{rand}{\sqrt{-3 + a \cdot 9}}\right) \]

Alternative 2
Accuracy	91.6%
Cost	7113

\[\begin{array}{l} \mathbf{if}\;rand \leq -3.2 \cdot 10^{+66} \lor \neg \left(rand \leq 1.3 \cdot 10^{+73}\right):\\ \;\;\;\;0.3333333333333333 \cdot \left(rand \cdot \sqrt{a - 0.3333333333333333}\right)\\ \mathbf{else}:\\ \;\;\;\;a - 0.3333333333333333\\ \end{array} \]

Alternative 3
Accuracy	98.5%
Cost	7104

\[\left(a + -0.3333333333333333\right) \cdot \left(1 + \frac{rand}{\sqrt{a \cdot 9}}\right) \]

Alternative 4
Accuracy	99.7%
Cost	7104

\[\left(a + -0.3333333333333333\right) + 0.3333333333333333 \cdot \left(rand \cdot \sqrt{a + -0.3333333333333333}\right) \]

Alternative 5
Accuracy	90.6%
Cost	6985

\[\begin{array}{l} \mathbf{if}\;rand \leq -3.8 \cdot 10^{+67} \lor \neg \left(rand \leq 2.15 \cdot 10^{+73}\right):\\ \;\;\;\;0.3333333333333333 \cdot \left(rand \cdot \sqrt{a}\right)\\ \mathbf{else}:\\ \;\;\;\;a - 0.3333333333333333\\ \end{array} \]

Alternative 6
Accuracy	71.7%
Cost	192

\[a - 0.3333333333333333 \]

Alternative 7
Accuracy	70.5%
Cost	64

\[a \]

Reproduce

herbie shell --seed 2023146 
(FPCore (a rand)
  :name "Octave 3.8, oct_fill_randg"
  :precision binary64
  (* (- a (/ 1.0 3.0)) (+ 1.0 (* (/ 1.0 (sqrt (* 9.0 (- a (/ 1.0 3.0))))) rand))))