Expression, p6

Average Error: 3.6 → 2.7

Time: 3.1s

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 r96681 = a;
        double r96682 = b;
        double r96683 = c;
        double r96684 = d;
        double r96685 = r96683 + r96684;
        double r96686 = r96682 + r96685;
        double r96687 = r96681 + r96686;
        double r96688 = 2.0;
        double r96689 = r96687 * r96688;
        return r96689;
}

↓

double f(double a, double b, double c, double d) {
        double r96690 = a;
        double r96691 = b;
        double r96692 = c;
        double r96693 = r96691 + r96692;
        double r96694 = d;
        double r96695 = r96693 + r96694;
        double r96696 = r96690 + r96695;
        double r96697 = 2.0;
        double r96698 = r96696 * r96697;
        return r96698;
}

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	2.7

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

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+ 2.7

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

4. Final simplification 2.7

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

Reproduce

herbie shell --seed 2020027 
(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))