Expression 1, p15

Average Error: 0.4 → 0.3

Time: 7.3s

Precision: 64

\[1 \le a \le 2 \le b \le 4 \le c \le 8 \le d \le 16 \le e \le 32\]

Math

\[\left(\left(\left(e + d\right) + c\right) + b\right) + a\]

↓

\[\left(\left(e + d\right) + c\right) + \left(b + a\right)\]

C

double f(double a, double b, double c, double d, double e) {
        double r111736 = e;
        double r111737 = d;
        double r111738 = r111736 + r111737;
        double r111739 = c;
        double r111740 = r111738 + r111739;
        double r111741 = b;
        double r111742 = r111740 + r111741;
        double r111743 = a;
        double r111744 = r111742 + r111743;
        return r111744;
}

↓

double f(double a, double b, double c, double d, double e) {
        double r111745 = e;
        double r111746 = d;
        double r111747 = r111745 + r111746;
        double r111748 = c;
        double r111749 = r111747 + r111748;
        double r111750 = b;
        double r111751 = a;
        double r111752 = r111750 + r111751;
        double r111753 = r111749 + r111752;
        return r111753;
}

Error

Bits error versus a

Bits error versus b

Bits error versus c

Bits error versus d

Bits error versus e

Target

Original	0.4
Target	0.2
Herbie	0.3

\[\left(d + \left(c + \left(a + b\right)\right)\right) + e\]

Derivation

1. Initial program 0.4

   \[\left(\left(\left(e + d\right) + c\right) + b\right) + a\]
2. Using strategy rm

3. Applied associate-+l+ 0.3

   \[\leadsto \color{blue}{\left(\left(e + d\right) + c\right) + \left(b + a\right)}\]

4. Final simplification 0.3

   \[\leadsto \left(\left(e + d\right) + c\right) + \left(b + a\right)\]

Reproduce

herbie shell --seed 2019356 +o rules:numerics
(FPCore (a b c d e)
  :name "Expression 1, p15"
  :precision binary64
  :pre (<= 1 a 2 b 4 c 8 d 16 e 32)

  :herbie-target
  (+ (+ d (+ c (+ a b))) e)

  (+ (+ (+ (+ e d) c) b) a))