Average Error: 0.0 → 0.0
Time: 1.9s
Precision: binary64
\[[x, y] = \mathsf{sort}([x, y]) \\]
\[\left(x \cdot x + \left(x \cdot 2\right) \cdot y\right) + y \cdot y \]
↓
\[\mathsf{fma}\left(2, y \cdot x, \mathsf{fma}\left(y, y, {x}^{2}\right)\right) \]
\left(x \cdot x + \left(x \cdot 2\right) \cdot y\right) + y \cdot y
↓
\mathsf{fma}\left(2, y \cdot x, \mathsf{fma}\left(y, y, {x}^{2}\right)\right)

(FPCore (x y) :precision binary64 (+ (+ (* x x) (* (* x 2.0) y)) (* y y)))
↓
(FPCore (x y) :precision binary64 (fma 2.0 (* y x) (fma y y (pow x 2.0))))
double code(double x, double y) {
	return ((x * x) + ((x * 2.0) * y)) + (y * y);
}
↓
double code(double x, double y) {
	return fma(2.0, (y * x), fma(y, y, pow(x, 2.0)));
}

Error

Bits error versus x

Bits error versus y

Target

Original0.0
Target0.0
Herbie0.0
\[x \cdot x + \left(y \cdot y + \left(x \cdot y\right) \cdot 2\right) \]

Derivation

  1. Initial program 0.0

    \[\left(x \cdot x + \left(x \cdot 2\right) \cdot y\right) + y \cdot y \]

  2. Taylor expanded in x around 0 0.0

    \[\leadsto \color{blue}{2 \cdot \left(y \cdot x\right) + \left({y}^{2} + {x}^{2}\right)} \]

  3. Applied unpow2_binary640.0

    \[\leadsto 2 \cdot \left(y \cdot x\right) + \left(\color{blue}{y \cdot y} + {x}^{2}\right) \]

  4. Applied fma-def_binary640.0

    \[\leadsto 2 \cdot \left(y \cdot x\right) + \color{blue}{\mathsf{fma}\left(y, y, {x}^{2}\right)} \]

  5. Applied fma-def_binary640.0

    \[\leadsto \color{blue}{\mathsf{fma}\left(2, y \cdot x, \mathsf{fma}\left(y, y, {x}^{2}\right)\right)} \]

  6. Final simplification0.0

    \[\leadsto \mathsf{fma}\left(2, y \cdot x, \mathsf{fma}\left(y, y, {x}^{2}\right)\right) \]

Reproduce

herbie shell --seed 2022081 
(FPCore (x y)
  :name "Examples.Basics.ProofTests:f4 from sbv-4.4"
  :precision binary64

  :herbie-target
  (+ (* x x) (+ (* y y) (* (* x y) 2.0)))

  (+ (+ (* x x) (* (* x 2.0) y)) (* y y)))