Average Error: 14.0 → 0.3
Time: 4.6s
Precision: binary64
\[\left(\frac{\pi}{2} \cdot \frac{1}{b \cdot b - a \cdot a}\right) \cdot \left(\frac{1}{a} - \frac{1}{b}\right) \]
↓
\[\frac{\frac{1}{\frac{a \cdot b}{\frac{\pi}{2}}}}{a + b} \]
\left(\frac{\pi}{2} \cdot \frac{1}{b \cdot b - a \cdot a}\right) \cdot \left(\frac{1}{a} - \frac{1}{b}\right)
↓
\frac{\frac{1}{\frac{a \cdot b}{\frac{\pi}{2}}}}{a + b}

(FPCore (a b)
 :precision binary64
 (* (* (/ PI 2.0) (/ 1.0 (- (* b b) (* a a)))) (- (/ 1.0 a) (/ 1.0 b))))
↓
(FPCore (a b) :precision binary64 (/ (/ 1.0 (/ (* a b) (/ PI 2.0))) (+ a b)))
double code(double a, double b) {
	return ((((double) M_PI) / 2.0) * (1.0 / ((b * b) - (a * a)))) * ((1.0 / a) - (1.0 / b));
}
↓
double code(double a, double b) {
	return (1.0 / ((a * b) / (((double) M_PI) / 2.0))) / (a + b);
}

Error

Bits error versus a

Bits error versus b

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Derivation

  1. Initial program 14.0

    \[\left(\frac{\pi}{2} \cdot \frac{1}{b \cdot b - a \cdot a}\right) \cdot \left(\frac{1}{a} - \frac{1}{b}\right) \]

  2. Simplified14.0

    \[\leadsto \color{blue}{\frac{\frac{\pi}{2}}{b \cdot b - a \cdot a} \cdot \left(\frac{1}{a} - \frac{1}{b}\right)} \]
  3. Using strategy rm

  4. Applied frac-sub_binary6414.0

    \[\leadsto \frac{\frac{\pi}{2}}{b \cdot b - a \cdot a} \cdot \color{blue}{\frac{1 \cdot b - a \cdot 1}{a \cdot b}} \]

  5. Applied associate-*r/_binary6414.0

    \[\leadsto \color{blue}{\frac{\frac{\frac{\pi}{2}}{b \cdot b - a \cdot a} \cdot \left(1 \cdot b - a \cdot 1\right)}{a \cdot b}} \]

  6. Simplified0.2

    \[\leadsto \frac{\color{blue}{\frac{\frac{\pi}{2}}{a + b} \cdot 1}}{a \cdot b} \]
  7. Using strategy rm

  8. Applied div-inv_binary640.3

    \[\leadsto \color{blue}{\left(\frac{\frac{\pi}{2}}{a + b} \cdot 1\right) \cdot \frac{1}{a \cdot b}} \]

  9. Simplified0.3

    \[\leadsto \left(\frac{\frac{\pi}{2}}{a + b} \cdot 1\right) \cdot \color{blue}{\frac{1}{b \cdot a}} \]
  10. Using strategy rm

  11. Applied associate-*l/_binary640.3

    \[\leadsto \color{blue}{\frac{\frac{\pi}{2} \cdot 1}{a + b}} \cdot \frac{1}{b \cdot a} \]

  12. Applied associate-*l/_binary640.3

    \[\leadsto \color{blue}{\frac{\left(\frac{\pi}{2} \cdot 1\right) \cdot \frac{1}{b \cdot a}}{a + b}} \]

  13. Simplified0.2

    \[\leadsto \frac{\color{blue}{\frac{\frac{\pi}{2}}{a \cdot b}}}{a + b} \]
  14. Using strategy rm

  15. Applied clear-num_binary640.3

    \[\leadsto \frac{\color{blue}{\frac{1}{\frac{a \cdot b}{\frac{\pi}{2}}}}}{a + b} \]

  16. Final simplification0.3

    \[\leadsto \frac{\frac{1}{\frac{a \cdot b}{\frac{\pi}{2}}}}{a + b} \]

Reproduce

herbie shell --seed 2021205 
(FPCore (a b)
  :name "NMSE Section 6.1 mentioned, B"
  :precision binary64
  (* (* (/ PI 2.0) (/ 1.0 (- (* b b) (* a a)))) (- (/ 1.0 a) (/ 1.0 b))))