(FPCore (x y z t a b)
:precision binary64
(+ (+ (+ x (* y z)) (* t a)) (* (* a z) b)))
↓
(FPCore (x y z t a b)
:precision binary64
(if (or (<= a -5e-58) (not (<= a 3e-12)))
(fma a (+ t (* z b)) (fma y z x))
(fma z (fma a b y) (fma t a x))))
\[\begin{array}{l}
\mathbf{if}\;z < -11820553527347888000:\\
\;\;\;\;z \cdot \left(b \cdot a + y\right) + \left(x + t \cdot a\right)\\
\mathbf{elif}\;z < 4.7589743188364287 \cdot 10^{-122}:\\
\;\;\;\;\left(b \cdot z + t\right) \cdot a + \left(z \cdot y + x\right)\\
\mathbf{else}:\\
\;\;\;\;z \cdot \left(b \cdot a + y\right) + \left(x + t \cdot a\right)\\
\end{array}
\]
Derivation
Split input into 2 regimes
if a < -4.99999999999999977e-58 or 3.0000000000000001e-12 < a
Initial program 4.2
\[\left(\left(x + y \cdot z\right) + t \cdot a\right) + \left(a \cdot z\right) \cdot b
\]
Simplified0.3
\[\leadsto \color{blue}{\mathsf{fma}\left(a, t + z \cdot b, \mathsf{fma}\left(y, z, x\right)\right)}
\]
Proof
(fma.f64 a (+.f64 t (*.f64 z b)) (fma.f64 y z x)): 0 points increase in error, 0 points decrease in error
(fma.f64 a (+.f64 t (*.f64 z b)) (Rewrite<= fma-def_binary64 (+.f64 (*.f64 y z) x))): 0 points increase in error, 9 points decrease in error
(fma.f64 a (+.f64 t (*.f64 z b)) (Rewrite<= +-commutative_binary64 (+.f64 x (*.f64 y z)))): 0 points increase in error, 0 points decrease in error
(Rewrite<= fma-def_binary64 (+.f64 (*.f64 a (+.f64 t (*.f64 z b))) (+.f64 x (*.f64 y z)))): 9 points increase in error, 0 points decrease in error
(+.f64 (Rewrite<= distribute-lft-out_binary64 (+.f64 (*.f64 a t) (*.f64 a (*.f64 z b)))) (+.f64 x (*.f64 y z))): 0 points increase in error, 9 points decrease in error
(+.f64 (+.f64 (Rewrite<= *-commutative_binary64 (*.f64 t a)) (*.f64 a (*.f64 z b))) (+.f64 x (*.f64 y z))): 0 points increase in error, 0 points decrease in error
(+.f64 (+.f64 (*.f64 t a) (Rewrite<= associate-*l*_binary64 (*.f64 (*.f64 a z) b))) (+.f64 x (*.f64 y z))): 0 points increase in error, 0 points decrease in error
(Rewrite<= +-commutative_binary64 (+.f64 (+.f64 x (*.f64 y z)) (+.f64 (*.f64 t a) (*.f64 (*.f64 a z) b)))): 3 points increase in error, 0 points decrease in error
(Rewrite<= associate-+l+_binary64 (+.f64 (+.f64 (+.f64 x (*.f64 y z)) (*.f64 t a)) (*.f64 (*.f64 a z) b))): 0 points increase in error, 3 points decrease in error
if -4.99999999999999977e-58 < a < 3.0000000000000001e-12
Initial program 0.4
\[\left(\left(x + y \cdot z\right) + t \cdot a\right) + \left(a \cdot z\right) \cdot b
\]
Simplified0.0
\[\leadsto \color{blue}{\mathsf{fma}\left(z, \mathsf{fma}\left(a, b, y\right), \mathsf{fma}\left(t, a, x\right)\right)}
\]
Proof
(fma.f64 a (+.f64 t (*.f64 z b)) (fma.f64 y z x)): 0 points increase in error, 0 points decrease in error
(fma.f64 a (+.f64 t (*.f64 z b)) (Rewrite<= fma-def_binary64 (+.f64 (*.f64 y z) x))): 0 points increase in error, 9 points decrease in error
(fma.f64 a (+.f64 t (*.f64 z b)) (Rewrite<= +-commutative_binary64 (+.f64 x (*.f64 y z)))): 0 points increase in error, 0 points decrease in error
(Rewrite<= fma-def_binary64 (+.f64 (*.f64 a (+.f64 t (*.f64 z b))) (+.f64 x (*.f64 y z)))): 9 points increase in error, 0 points decrease in error
(+.f64 (Rewrite<= distribute-lft-out_binary64 (+.f64 (*.f64 a t) (*.f64 a (*.f64 z b)))) (+.f64 x (*.f64 y z))): 0 points increase in error, 9 points decrease in error
(+.f64 (+.f64 (Rewrite<= *-commutative_binary64 (*.f64 t a)) (*.f64 a (*.f64 z b))) (+.f64 x (*.f64 y z))): 0 points increase in error, 0 points decrease in error
(+.f64 (+.f64 (*.f64 t a) (Rewrite<= associate-*l*_binary64 (*.f64 (*.f64 a z) b))) (+.f64 x (*.f64 y z))): 0 points increase in error, 0 points decrease in error
(Rewrite<= +-commutative_binary64 (+.f64 (+.f64 x (*.f64 y z)) (+.f64 (*.f64 t a) (*.f64 (*.f64 a z) b)))): 3 points increase in error, 0 points decrease in error
(Rewrite<= associate-+l+_binary64 (+.f64 (+.f64 (+.f64 x (*.f64 y z)) (*.f64 t a)) (*.f64 (*.f64 a z) b))): 0 points increase in error, 3 points decrease in error
herbie shell --seed 2022343
(FPCore (x y z t a b)
:name "Graphics.Rasterific.CubicBezier:cachedBezierAt from Rasterific-0.6.1"
:precision binary64
:herbie-target
(if (< z -11820553527347888000.0) (+ (* z (+ (* b a) y)) (+ x (* t a))) (if (< z 4.7589743188364287e-122) (+ (* (+ (* b z) t) a) (+ (* z y) x)) (+ (* z (+ (* b a) y)) (+ x (* t a)))))
(+ (+ (+ x (* y z)) (* t a)) (* (* a z) b)))