Expression, p6

Average Error: 3.7 → 2.8

Time: 3.2s

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 r109472 = a;
        double r109473 = b;
        double r109474 = c;
        double r109475 = d;
        double r109476 = r109474 + r109475;
        double r109477 = r109473 + r109476;
        double r109478 = r109472 + r109477;
        double r109479 = 2.0;
        double r109480 = r109478 * r109479;
        return r109480;
}

↓

double f(double a, double b, double c, double d) {
        double r109481 = a;
        double r109482 = b;
        double r109483 = c;
        double r109484 = r109482 + r109483;
        double r109485 = d;
        double r109486 = r109484 + r109485;
        double r109487 = r109481 + r109486;
        double r109488 = 2.0;
        double r109489 = r109487 * r109488;
        return r109489;
}

Error

Bits error versus a

Bits error versus b

Bits error versus c

Bits error versus d

Target

Original	3.7
Target	3.8
Herbie	2.8

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

Derivation

1. Initial program 3.7

   \[\left(a + \left(b + \left(c + d\right)\right)\right) \cdot 2\]
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 2020060 
(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))