Diagrams.Solve.Tridiagonal:solveCyclicTriDiagonal from diagrams-solve-0.1, A

Average Error: 9.51% → 1.23%

Time: 3.0s

Precision: binary64

Cost: 1360

\[ \begin{array}{c}[x, y] = \mathsf{sort}([x, y])\\ \end{array} \]

Math

\[\frac{x \cdot y}{z} \]

↓

\[\begin{array}{l} t_0 := x \cdot \frac{y}{z}\\ t_1 := \frac{x \cdot y}{z}\\ \mathbf{if}\;x \cdot y \leq -1 \cdot 10^{+150}:\\ \;\;\;\;t_0\\ \mathbf{elif}\;x \cdot y \leq -4 \cdot 10^{-205}:\\ \;\;\;\;t_1\\ \mathbf{elif}\;x \cdot y \leq 2 \cdot 10^{-322}:\\ \;\;\;\;t_0\\ \mathbf{elif}\;x \cdot y \leq 2 \cdot 10^{+136}:\\ \;\;\;\;t_1\\ \mathbf{else}:\\ \;\;\;\;y \cdot \frac{x}{z}\\ \end{array} \]

FPCore

(FPCore (x y z) :precision binary64 (/ (* x y) z))

↓

(FPCore (x y z)
 :precision binary64
 (let* ((t_0 (* x (/ y z))) (t_1 (/ (* x y) z)))
   (if (<= (* x y) -1e+150)
     t_0
     (if (<= (* x y) -4e-205)
       t_1
       (if (<= (* x y) 2e-322)
         t_0
         (if (<= (* x y) 2e+136) t_1 (* y (/ x z))))))))

C

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

↓

double code(double x, double y, double z) {
	double t_0 = x * (y / z);
	double t_1 = (x * y) / z;
	double tmp;
	if ((x * y) <= -1e+150) {
		tmp = t_0;
	} else if ((x * y) <= -4e-205) {
		tmp = t_1;
	} else if ((x * y) <= 2e-322) {
		tmp = t_0;
	} else if ((x * y) <= 2e+136) {
		tmp = t_1;
	} else {
		tmp = y * (x / z);
	}
	return tmp;
}

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 * y) / z
end function

↓

real(8) function code(x, y, z)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    real(8), intent (in) :: z
    real(8) :: t_0
    real(8) :: t_1
    real(8) :: tmp
    t_0 = x * (y / z)
    t_1 = (x * y) / z
    if ((x * y) <= (-1d+150)) then
        tmp = t_0
    else if ((x * y) <= (-4d-205)) then
        tmp = t_1
    else if ((x * y) <= 2d-322) then
        tmp = t_0
    else if ((x * y) <= 2d+136) then
        tmp = t_1
    else
        tmp = y * (x / z)
    end if
    code = tmp
end function

Java

public static double code(double x, double y, double z) {
	return (x * y) / z;
}

↓

public static double code(double x, double y, double z) {
	double t_0 = x * (y / z);
	double t_1 = (x * y) / z;
	double tmp;
	if ((x * y) <= -1e+150) {
		tmp = t_0;
	} else if ((x * y) <= -4e-205) {
		tmp = t_1;
	} else if ((x * y) <= 2e-322) {
		tmp = t_0;
	} else if ((x * y) <= 2e+136) {
		tmp = t_1;
	} else {
		tmp = y * (x / z);
	}
	return tmp;
}

Python

def code(x, y, z):
	return (x * y) / z

↓

def code(x, y, z):
	t_0 = x * (y / z)
	t_1 = (x * y) / z
	tmp = 0
	if (x * y) <= -1e+150:
		tmp = t_0
	elif (x * y) <= -4e-205:
		tmp = t_1
	elif (x * y) <= 2e-322:
		tmp = t_0
	elif (x * y) <= 2e+136:
		tmp = t_1
	else:
		tmp = y * (x / z)
	return tmp

Julia

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

↓

function code(x, y, z)
	t_0 = Float64(x * Float64(y / z))
	t_1 = Float64(Float64(x * y) / z)
	tmp = 0.0
	if (Float64(x * y) <= -1e+150)
		tmp = t_0;
	elseif (Float64(x * y) <= -4e-205)
		tmp = t_1;
	elseif (Float64(x * y) <= 2e-322)
		tmp = t_0;
	elseif (Float64(x * y) <= 2e+136)
		tmp = t_1;
	else
		tmp = Float64(y * Float64(x / z));
	end
	return tmp
end

MATLAB

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

↓

function tmp_2 = code(x, y, z)
	t_0 = x * (y / z);
	t_1 = (x * y) / z;
	tmp = 0.0;
	if ((x * y) <= -1e+150)
		tmp = t_0;
	elseif ((x * y) <= -4e-205)
		tmp = t_1;
	elseif ((x * y) <= 2e-322)
		tmp = t_0;
	elseif ((x * y) <= 2e+136)
		tmp = t_1;
	else
		tmp = y * (x / z);
	end
	tmp_2 = tmp;
end

Wolfram

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

↓

code[x_, y_, z_] := Block[{t$95$0 = N[(x * N[(y / z), $MachinePrecision]), $MachinePrecision]}, Block[{t$95$1 = N[(N[(x * y), $MachinePrecision] / z), $MachinePrecision]}, If[LessEqual[N[(x * y), $MachinePrecision], -1e+150], t$95$0, If[LessEqual[N[(x * y), $MachinePrecision], -4e-205], t$95$1, If[LessEqual[N[(x * y), $MachinePrecision], 2e-322], t$95$0, If[LessEqual[N[(x * y), $MachinePrecision], 2e+136], t$95$1, N[(y * N[(x / z), $MachinePrecision]), $MachinePrecision]]]]]]]

Target

Original	9.51%
Target	9.63%
Herbie	1.23%

\[\begin{array}{l} \mathbf{if}\;z < -4.262230790519429 \cdot 10^{-138}:\\ \;\;\;\;\frac{x \cdot y}{z}\\ \mathbf{elif}\;z < 1.7042130660650472 \cdot 10^{-164}:\\ \;\;\;\;\frac{x}{\frac{z}{y}}\\ \mathbf{else}:\\ \;\;\;\;\frac{x}{z} \cdot y\\ \end{array} \]

Derivation

1. Split input into 3 regimes

2. if (*.f64 x y) < -9.99999999999999981e149 or -4e-205 < (*.f64 x y) < 1.97626e-322

   1. Initial program 23.13

      \[\frac{x \cdot y}{z} \]

   2. Simplified 1.58

      \[\leadsto \color{blue}{x \cdot \frac{y}{z}} \]
      Proof

      [Start] 23.13	\[ \frac{x \cdot y}{z} \]
      associate-*r/ [<=] 1.58	\[ \color{blue}{x \cdot \frac{y}{z}} \]

   if -9.99999999999999981e149 < (*.f64 x y) < -4e-205 or 1.97626e-322 < (*.f64 x y) < 2.00000000000000012e136

   1. Initial program 0.54

      \[\frac{x \cdot y}{z} \]

   if 2.00000000000000012e136 < (*.f64 x y)

   1. Initial program 25.86

      \[\frac{x \cdot y}{z} \]

   2. Simplified 4.46

      \[\leadsto \color{blue}{\frac{x}{z} \cdot y} \]
      Proof

      [Start] 25.86	\[ \frac{x \cdot y}{z} \]
      associate-*l/ [<=] 4.46	\[ \color{blue}{\frac{x}{z} \cdot y} \]

3. Recombined 3 regimes into one program.

4. Final simplification 1.23

   \[\leadsto \begin{array}{l} \mathbf{if}\;x \cdot y \leq -1 \cdot 10^{+150}:\\ \;\;\;\;x \cdot \frac{y}{z}\\ \mathbf{elif}\;x \cdot y \leq -4 \cdot 10^{-205}:\\ \;\;\;\;\frac{x \cdot y}{z}\\ \mathbf{elif}\;x \cdot y \leq 2 \cdot 10^{-322}:\\ \;\;\;\;x \cdot \frac{y}{z}\\ \mathbf{elif}\;x \cdot y \leq 2 \cdot 10^{+136}:\\ \;\;\;\;\frac{x \cdot y}{z}\\ \mathbf{else}:\\ \;\;\;\;y \cdot \frac{x}{z}\\ \end{array} \]

Alternatives

Alternative 1
Error	9.69%
Cost	452

\[\begin{array}{l} \mathbf{if}\;z \leq -1.15 \cdot 10^{-280}:\\ \;\;\;\;x \cdot \frac{y}{z}\\ \mathbf{else}:\\ \;\;\;\;y \cdot \frac{x}{z}\\ \end{array} \]

Alternative 2
Error	9.73%
Cost	452

\[\begin{array}{l} \mathbf{if}\;z \leq -7.6 \cdot 10^{-282}:\\ \;\;\;\;\frac{x}{\frac{z}{y}}\\ \mathbf{else}:\\ \;\;\;\;y \cdot \frac{x}{z}\\ \end{array} \]

Alternative 3
Error	9.88%
Cost	320

\[x \cdot \frac{y}{z} \]

Reproduce

herbie shell --seed 2023121 
(FPCore (x y z)
  :name "Diagrams.Solve.Tridiagonal:solveCyclicTriDiagonal from diagrams-solve-0.1, A"
  :precision binary64

  :herbie-target
  (if (< z -4.262230790519429e-138) (/ (* x y) z) (if (< z 1.7042130660650472e-164) (/ x (/ z y)) (* (/ x z) y)))

  (/ (* x y) z))