Octave 3.8, oct_fill_randg

Percentage Accurate: 99.8% → 99.8%

Time: 9.7s

Alternatives: 8

Speedup: 2.4×

Specification

Math

\[\begin{array}{l} \\ \begin{array}{l} t_0 := a - \frac{1}{3}\\ t\_0 \cdot \left(1 + \frac{1}{\sqrt{9 \cdot t\_0}} \cdot rand\right) \end{array} \end{array} \]

FPCore

(FPCore (a rand)
 :precision binary64
 (let* ((t_0 (- a (/ 1.0 3.0))))
   (* t_0 (+ 1.0 (* (/ 1.0 (sqrt (* 9.0 t_0))) rand)))))

C

double code(double a, double rand) {
	double t_0 = a - (1.0 / 3.0);
	return t_0 * (1.0 + ((1.0 / sqrt((9.0 * t_0))) * rand));
}

Fortran

real(8) function code(a, rand)
    real(8), intent (in) :: a
    real(8), intent (in) :: rand
    real(8) :: t_0
    t_0 = a - (1.0d0 / 3.0d0)
    code = t_0 * (1.0d0 + ((1.0d0 / sqrt((9.0d0 * t_0))) * rand))
end function

Java

public static double code(double a, double rand) {
	double t_0 = a - (1.0 / 3.0);
	return t_0 * (1.0 + ((1.0 / Math.sqrt((9.0 * t_0))) * rand));
}

Python

def code(a, rand):
	t_0 = a - (1.0 / 3.0)
	return t_0 * (1.0 + ((1.0 / math.sqrt((9.0 * t_0))) * rand))

Julia

function code(a, rand)
	t_0 = Float64(a - Float64(1.0 / 3.0))
	return Float64(t_0 * Float64(1.0 + Float64(Float64(1.0 / sqrt(Float64(9.0 * t_0))) * rand)))
end

MATLAB

function tmp = code(a, rand)
	t_0 = a - (1.0 / 3.0);
	tmp = t_0 * (1.0 + ((1.0 / sqrt((9.0 * t_0))) * rand));
end

Wolfram

code[a_, rand_] := Block[{t$95$0 = N[(a - N[(1.0 / 3.0), $MachinePrecision]), $MachinePrecision]}, N[(t$95$0 * N[(1.0 + N[(N[(1.0 / N[Sqrt[N[(9.0 * t$95$0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * rand), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]

Initial Program: 99.8% accurate, 1.0× speedup

Math

\[\begin{array}{l} \\ \begin{array}{l} t_0 := a - \frac{1}{3}\\ t\_0 \cdot \left(1 + \frac{1}{\sqrt{9 \cdot t\_0}} \cdot rand\right) \end{array} \end{array} \]

FPCore

(FPCore (a rand)
 :precision binary64
 (let* ((t_0 (- a (/ 1.0 3.0))))
   (* t_0 (+ 1.0 (* (/ 1.0 (sqrt (* 9.0 t_0))) rand)))))

C

double code(double a, double rand) {
	double t_0 = a - (1.0 / 3.0);
	return t_0 * (1.0 + ((1.0 / sqrt((9.0 * t_0))) * rand));
}

Fortran

real(8) function code(a, rand)
    real(8), intent (in) :: a
    real(8), intent (in) :: rand
    real(8) :: t_0
    t_0 = a - (1.0d0 / 3.0d0)
    code = t_0 * (1.0d0 + ((1.0d0 / sqrt((9.0d0 * t_0))) * rand))
end function

Java

public static double code(double a, double rand) {
	double t_0 = a - (1.0 / 3.0);
	return t_0 * (1.0 + ((1.0 / Math.sqrt((9.0 * t_0))) * rand));
}

Python

def code(a, rand):
	t_0 = a - (1.0 / 3.0)
	return t_0 * (1.0 + ((1.0 / math.sqrt((9.0 * t_0))) * rand))

Julia

function code(a, rand)
	t_0 = Float64(a - Float64(1.0 / 3.0))
	return Float64(t_0 * Float64(1.0 + Float64(Float64(1.0 / sqrt(Float64(9.0 * t_0))) * rand)))
end

MATLAB

function tmp = code(a, rand)
	t_0 = a - (1.0 / 3.0);
	tmp = t_0 * (1.0 + ((1.0 / sqrt((9.0 * t_0))) * rand));
end

Wolfram

code[a_, rand_] := Block[{t$95$0 = N[(a - N[(1.0 / 3.0), $MachinePrecision]), $MachinePrecision]}, N[(t$95$0 * N[(1.0 + N[(N[(1.0 / N[Sqrt[N[(9.0 * t$95$0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] * rand), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]

Alternative 1: 99.8% accurate, 2.4× speedup

Math

\[\begin{array}{l} \\ \mathsf{fma}\left(rand \cdot 0.3333333333333333, \sqrt{a - 0.3333333333333333}, a - 0.3333333333333333\right) \end{array} \]

FPCore

(FPCore (a rand)
 :precision binary64
 (fma
  (* rand 0.3333333333333333)
  (sqrt (- a 0.3333333333333333))
  (- a 0.3333333333333333)))

C

double code(double a, double rand) {
	return fma((rand * 0.3333333333333333), sqrt((a - 0.3333333333333333)), (a - 0.3333333333333333));
}

Julia

function code(a, rand)
	return fma(Float64(rand * 0.3333333333333333), sqrt(Float64(a - 0.3333333333333333)), Float64(a - 0.3333333333333333))
end

Wolfram

code[a_, rand_] := N[(N[(rand * 0.3333333333333333), $MachinePrecision] * N[Sqrt[N[(a - 0.3333333333333333), $MachinePrecision]], $MachinePrecision] + N[(a - 0.3333333333333333), $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. Add Preprocessing

3. Taylor expanded in rand around 0

   \[\leadsto \color{blue}{\left(a + \frac{1}{3} \cdot \left(rand \cdot \sqrt{a - \frac{1}{3}}\right)\right) - \frac{1}{3}} \]
4. Step-by-step derivation

   1. +-commutative N/A

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

   2. associate--l+ N/A

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

   3. associate-*r* N/A

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

   4. lower-fma.f64 N/A

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

   5. *-commutative N/A

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

   6. lower-*.f64 N/A

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

   7. lower-sqrt.f64 N/A

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

   8. lower--.f64 N/A

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

   9. lower--.f64 99.8

      \[\leadsto \mathsf{fma}\left(rand \cdot 0.3333333333333333, \sqrt{a - 0.3333333333333333}, \color{blue}{a - 0.3333333333333333}\right) \]

5. Applied rewrites 99.8%

   \[\leadsto \color{blue}{\mathsf{fma}\left(rand \cdot 0.3333333333333333, \sqrt{a - 0.3333333333333333}, a - 0.3333333333333333\right)} \]
6. Add Preprocessing

Alternative 2: 92.9% accurate, 2.1× speedup

Math

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;rand \leq -8 \cdot 10^{+77}:\\ \;\;\;\;\sqrt{a} \cdot \left(rand \cdot 0.3333333333333333\right)\\ \mathbf{elif}\;rand \leq 9 \cdot 10^{+73}:\\ \;\;\;\;a - 0.3333333333333333\\ \mathbf{else}:\\ \;\;\;\;\left(\sqrt{a} \cdot 0.3333333333333333\right) \cdot rand\\ \end{array} \end{array} \]

FPCore

(FPCore (a rand)
 :precision binary64
 (if (<= rand -8e+77)
   (* (sqrt a) (* rand 0.3333333333333333))
   (if (<= rand 9e+73)
     (- a 0.3333333333333333)
     (* (* (sqrt a) 0.3333333333333333) rand))))

C

double code(double a, double rand) {
	double tmp;
	if (rand <= -8e+77) {
		tmp = sqrt(a) * (rand * 0.3333333333333333);
	} else if (rand <= 9e+73) {
		tmp = a - 0.3333333333333333;
	} else {
		tmp = (sqrt(a) * 0.3333333333333333) * rand;
	}
	return tmp;
}

Fortran

real(8) function code(a, rand)
    real(8), intent (in) :: a
    real(8), intent (in) :: rand
    real(8) :: tmp
    if (rand <= (-8d+77)) then
        tmp = sqrt(a) * (rand * 0.3333333333333333d0)
    else if (rand <= 9d+73) then
        tmp = a - 0.3333333333333333d0
    else
        tmp = (sqrt(a) * 0.3333333333333333d0) * rand
    end if
    code = tmp
end function

Java

public static double code(double a, double rand) {
	double tmp;
	if (rand <= -8e+77) {
		tmp = Math.sqrt(a) * (rand * 0.3333333333333333);
	} else if (rand <= 9e+73) {
		tmp = a - 0.3333333333333333;
	} else {
		tmp = (Math.sqrt(a) * 0.3333333333333333) * rand;
	}
	return tmp;
}

Python

def code(a, rand):
	tmp = 0
	if rand <= -8e+77:
		tmp = math.sqrt(a) * (rand * 0.3333333333333333)
	elif rand <= 9e+73:
		tmp = a - 0.3333333333333333
	else:
		tmp = (math.sqrt(a) * 0.3333333333333333) * rand
	return tmp

Julia

function code(a, rand)
	tmp = 0.0
	if (rand <= -8e+77)
		tmp = Float64(sqrt(a) * Float64(rand * 0.3333333333333333));
	elseif (rand <= 9e+73)
		tmp = Float64(a - 0.3333333333333333);
	else
		tmp = Float64(Float64(sqrt(a) * 0.3333333333333333) * rand);
	end
	return tmp
end

MATLAB

function tmp_2 = code(a, rand)
	tmp = 0.0;
	if (rand <= -8e+77)
		tmp = sqrt(a) * (rand * 0.3333333333333333);
	elseif (rand <= 9e+73)
		tmp = a - 0.3333333333333333;
	else
		tmp = (sqrt(a) * 0.3333333333333333) * rand;
	end
	tmp_2 = tmp;
end

Wolfram

code[a_, rand_] := If[LessEqual[rand, -8e+77], N[(N[Sqrt[a], $MachinePrecision] * N[(rand * 0.3333333333333333), $MachinePrecision]), $MachinePrecision], If[LessEqual[rand, 9e+73], N[(a - 0.3333333333333333), $MachinePrecision], N[(N[(N[Sqrt[a], $MachinePrecision] * 0.3333333333333333), $MachinePrecision] * rand), $MachinePrecision]]]

Derivation

1. Split input into 3 regimes

2. if rand < -7.99999999999999986e77

   1. Initial program 99.6%

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

   3. Taylor expanded in rand around inf

      \[\leadsto \color{blue}{\frac{1}{3} \cdot \left(rand \cdot \sqrt{a - \frac{1}{3}}\right)} \]
   4. Step-by-step derivation

      1. associate-*r* N/A

         \[\leadsto \color{blue}{\left(\frac{1}{3} \cdot rand\right) \cdot \sqrt{a - \frac{1}{3}}} \]

      2. lower-*.f64 N/A

         \[\leadsto \color{blue}{\left(\frac{1}{3} \cdot rand\right) \cdot \sqrt{a - \frac{1}{3}}} \]

      3. *-commutative N/A

         \[\leadsto \color{blue}{\left(rand \cdot \frac{1}{3}\right)} \cdot \sqrt{a - \frac{1}{3}} \]

      4. lower-*.f64 N/A

         \[\leadsto \color{blue}{\left(rand \cdot \frac{1}{3}\right)} \cdot \sqrt{a - \frac{1}{3}} \]

      5. lower-sqrt.f64 N/A

         \[\leadsto \left(rand \cdot \frac{1}{3}\right) \cdot \color{blue}{\sqrt{a - \frac{1}{3}}} \]

      6. lower--.f64 90.6

         \[\leadsto \left(rand \cdot 0.3333333333333333\right) \cdot \sqrt{\color{blue}{a - 0.3333333333333333}} \]

   5. Applied rewrites 90.6%

      \[\leadsto \color{blue}{\left(rand \cdot 0.3333333333333333\right) \cdot \sqrt{a - 0.3333333333333333}} \]

   6. Taylor expanded in a around inf

      \[\leadsto \left(rand \cdot \frac{1}{3}\right) \cdot \sqrt{a} \]
   7. Step-by-step derivation

   8. Applied rewrites 87.9%

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

   if -7.99999999999999986e77 < rand < 8.99999999999999969e73

   1. Initial program 100.0%

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

   3. Taylor expanded in rand around 0

      \[\leadsto \color{blue}{a - \frac{1}{3}} \]
   4. Step-by-step derivation

      1. lower--.f64 95.2

         \[\leadsto \color{blue}{a - 0.3333333333333333} \]

   5. Applied rewrites 95.2%

      \[\leadsto \color{blue}{a - 0.3333333333333333} \]

   if 8.99999999999999969e73 < rand

   1. Initial program 99.5%

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

   3. Taylor expanded in a around inf

      \[\leadsto \color{blue}{a \cdot \left(1 + \frac{1}{3} \cdot \left(\sqrt{\frac{1}{a}} \cdot rand\right)\right)} \]
   4. Step-by-step derivation

      1. *-commutative N/A

         \[\leadsto \color{blue}{\left(1 + \frac{1}{3} \cdot \left(\sqrt{\frac{1}{a}} \cdot rand\right)\right) \cdot a} \]

      2. lower-*.f64 N/A

         \[\leadsto \color{blue}{\left(1 + \frac{1}{3} \cdot \left(\sqrt{\frac{1}{a}} \cdot rand\right)\right) \cdot a} \]

      3. +-commutative N/A

         \[\leadsto \color{blue}{\left(\frac{1}{3} \cdot \left(\sqrt{\frac{1}{a}} \cdot rand\right) + 1\right)} \cdot a \]

      4. *-commutative N/A

         \[\leadsto \left(\frac{1}{3} \cdot \color{blue}{\left(rand \cdot \sqrt{\frac{1}{a}}\right)} + 1\right) \cdot a \]

      5. associate-*r* N/A

         \[\leadsto \left(\color{blue}{\left(\frac{1}{3} \cdot rand\right) \cdot \sqrt{\frac{1}{a}}} + 1\right) \cdot a \]

      6. lower-fma.f64 N/A

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

      7. *-commutative N/A

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

      8. lower-*.f64 N/A

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

      9. lower-sqrt.f64 N/A

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

      10. lower-/.f64 98.2

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

   5. Applied rewrites 98.2%

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

   6. Taylor expanded in rand around inf

      \[\leadsto \frac{1}{3} \cdot \color{blue}{\left(\sqrt{a} \cdot rand\right)} \]
   7. Step-by-step derivation

   8. Applied rewrites 89.5%

      \[\leadsto \left(\sqrt{a} \cdot 0.3333333333333333\right) \cdot \color{blue}{rand} \]
3. Recombined 3 regimes into one program.

4. Final simplification 92.9%

   \[\leadsto \begin{array}{l} \mathbf{if}\;rand \leq -8 \cdot 10^{+77}:\\ \;\;\;\;\sqrt{a} \cdot \left(rand \cdot 0.3333333333333333\right)\\ \mathbf{elif}\;rand \leq 9 \cdot 10^{+73}:\\ \;\;\;\;a - 0.3333333333333333\\ \mathbf{else}:\\ \;\;\;\;\left(\sqrt{a} \cdot 0.3333333333333333\right) \cdot rand\\ \end{array} \]
5. Add Preprocessing

Reproduce

herbie shell --seed 2024230 
(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))))