Average Error: 7.8 → 0.3
Time: 3.7s
Precision: binary64
\[0.999 \leq x \land x \leq 1.001\]
\[\frac{10}{1 - x \cdot x} \]
↓
\[\frac{-10}{\mathsf{fma}\left(x, x, -1\right)} \]
\frac{10}{1 - x \cdot x}
↓
\frac{-10}{\mathsf{fma}\left(x, x, -1\right)}

(FPCore (x) :precision binary64 (/ 10.0 (- 1.0 (* x x))))
↓
(FPCore (x) :precision binary64 (/ -10.0 (fma x x -1.0)))
double code(double x) {
	return 10.0 / (1.0 - (x * x));
}
↓
double code(double x) {
	return -10.0 / fma(x, x, -1.0);
}

Error

Bits error versus x

Derivation

  1. Initial program 7.8

    \[\frac{10}{1 - x \cdot x} \]

  2. Simplified0.3

    \[\leadsto \color{blue}{\frac{-10}{\mathsf{fma}\left(x, x, -1\right)}} \]

  3. Final simplification0.3

    \[\leadsto \frac{-10}{\mathsf{fma}\left(x, x, -1\right)} \]

Reproduce

herbie shell --seed 2022130 
(FPCore (x)
  :name "ENA, Section 1.4, Mentioned, B"
  :precision binary64
  :pre (and (<= 0.999 x) (<= x 1.001))
  (/ 10.0 (- 1.0 (* x x))))