Expression 1, p15

Average Error: 0.4 → 0.3

Time: 7.8s

Precision: 64

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

Math

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

↓

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

C

double f(double a, double b, double c, double d, double e) {
        double r14074 = e;
        double r14075 = d;
        double r14076 = r14074 + r14075;
        double r14077 = c;
        double r14078 = r14076 + r14077;
        double r14079 = b;
        double r14080 = r14078 + r14079;
        double r14081 = a;
        double r14082 = r14080 + r14081;
        return r14082;
}

↓

double f(double a, double b, double c, double d, double e) {
        double r14083 = e;
        double r14084 = d;
        double r14085 = r14083 + r14084;
        double r14086 = c;
        double r14087 = b;
        double r14088 = a;
        double r14089 = r14087 + r14088;
        double r14090 = r14086 + r14089;
        double r14091 = r14085 + r14090;
        return r14091;
}

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. Using strategy rm

5. Applied associate-+l+ 0.3

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

6. Final simplification 0.3

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

Reproduce

herbie shell --seed 2019310 +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))