Expression, p6

Average Error: 3.6 → 2.8

Time: 3.3s

Precision: 64

\[-14 \le a \le -13 \land -3 \le b \le -2 \land 3 \le c \le 3.5 \land 12.5 \le d \le 13.5\]

Math

\[\left(a + \left(b + \left(c + d\right)\right)\right) \cdot 2\]

↓

\[\left(a + \left(\left(b + c\right) + d\right)\right) \cdot 2\]

C

double f(double a, double b, double c, double d) {
        double r93851 = a;
        double r93852 = b;
        double r93853 = c;
        double r93854 = d;
        double r93855 = r93853 + r93854;
        double r93856 = r93852 + r93855;
        double r93857 = r93851 + r93856;
        double r93858 = 2.0;
        double r93859 = r93857 * r93858;
        return r93859;
}

↓

double f(double a, double b, double c, double d) {
        double r93860 = a;
        double r93861 = b;
        double r93862 = c;
        double r93863 = r93861 + r93862;
        double r93864 = d;
        double r93865 = r93863 + r93864;
        double r93866 = r93860 + r93865;
        double r93867 = 2.0;
        double r93868 = r93866 * r93867;
        return r93868;
}

Error

Bits error versus a

Bits error versus b

Bits error versus c

Bits error versus d

Target

Original	3.6
Target	3.8
Herbie	2.8

\[\left(a + b\right) \cdot 2 + \left(c + d\right) \cdot 2\]

Derivation

1. Initial program 3.6

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

3. Applied associate-+r+ 2.8

   \[\leadsto \left(a + \color{blue}{\left(\left(b + c\right) + d\right)}\right) \cdot 2\]

4. Final simplification 2.8

   \[\leadsto \left(a + \left(\left(b + c\right) + d\right)\right) \cdot 2\]

Reproduce

herbie shell --seed 2019353 
(FPCore (a b c d)
  :name "Expression, p6"
  :precision binary64
  :pre (and (<= -14 a -13) (<= -3 b -2) (<= 3 c 3.5) (<= 12.5 d 13.5))

  :herbie-target
  (+ (* (+ a b) 2) (* (+ c d) 2))

  (* (+ a (+ b (+ c d))) 2))