Expression, p6

Average Error: 3.6 → 2.8

Time: 11.0s

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 r57494 = a;
        double r57495 = b;
        double r57496 = c;
        double r57497 = d;
        double r57498 = r57496 + r57497;
        double r57499 = r57495 + r57498;
        double r57500 = r57494 + r57499;
        double r57501 = 2.0;
        double r57502 = r57500 * r57501;
        return r57502;
}

↓

double f(double a, double b, double c, double d) {
        double r57503 = a;
        double r57504 = b;
        double r57505 = c;
        double r57506 = r57504 + r57505;
        double r57507 = d;
        double r57508 = r57506 + r57507;
        double r57509 = r57503 + r57508;
        double r57510 = 2.0;
        double r57511 = r57509 * r57510;
        return r57511;
}

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 2019323 
(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))