Diagrams.Solve.Tridiagonal:solveTriDiagonal from diagrams-solve-0.1, C

Average Accuracy: 100.0% → 100.0%

Time: 1.9s

Precision: binary64

Cost: 6656

• Unsound rule application detected in e-graph. Results may not be sound.

Math

\[x - y \cdot z \]

↓

\[\mathsf{fma}\left(y, -z, x\right) \]

FPCore

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

↓

(FPCore (x y z) :precision binary64 (fma y (- z) x))

C

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

↓

double code(double x, double y, double z) {
	return fma(y, -z, x);
}

Julia

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

↓

function code(x, y, z)
	return fma(y, Float64(-z), x)
end

Wolfram

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

↓

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

Target

Original	100.0%
Target	87.5%
Herbie	100.0%

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

Derivation

1. Initial program 100.0%

   \[x - y \cdot z \]

2. Simplified 100.0%

   \[\leadsto \color{blue}{\mathsf{fma}\left(y, -z, x\right)} \]
   Proof

   [Start] 100.0	\[ x - y \cdot z \]
   sub-neg [=>] 100.0	\[ \color{blue}{x + \left(-y \cdot z\right)} \]
   +-commutative [=>] 100.0	\[ \color{blue}{\left(-y \cdot z\right) + x} \]
   distribute-rgt-neg-in [=>] 100.0	\[ \color{blue}{y \cdot \left(-z\right)} + x \]
   fma-def [=>] 100.0	\[ \color{blue}{\mathsf{fma}\left(y, -z, x\right)} \]

3. Final simplification 100.0%

   \[\leadsto \mathsf{fma}\left(y, -z, x\right) \]

Alternatives

Alternative 1
Accuracy	69.1%
Cost	786

\[\begin{array}{l} \mathbf{if}\;y \leq -7.8 \cdot 10^{+124} \lor \neg \left(y \leq -8.5 \cdot 10^{+75} \lor \neg \left(y \leq -2.2 \cdot 10^{+45}\right) \land y \leq 6.1 \cdot 10^{-55}\right):\\ \;\;\;\;-y \cdot z\\ \mathbf{else}:\\ \;\;\;\;x\\ \end{array} \]

Alternative 2
Accuracy	100.0%
Cost	320

\[x - y \cdot z \]

Alternative 3
Accuracy	51.1%
Cost	64

\[x \]

Reproduce

herbie shell --seed 2023160 
(FPCore (x y z)
  :name "Diagrams.Solve.Tridiagonal:solveTriDiagonal from diagrams-solve-0.1, C"
  :precision binary64

  :herbie-target
  (/ (+ x (* y z)) (/ (+ x (* y z)) (- x (* y z))))

  (- x (* y z)))