Expression, p6

Average Error: 3.7 → 2.8

Time: 10.0s

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 r51203 = a;
        double r51204 = b;
        double r51205 = c;
        double r51206 = d;
        double r51207 = r51205 + r51206;
        double r51208 = r51204 + r51207;
        double r51209 = r51203 + r51208;
        double r51210 = 2.0;
        double r51211 = r51209 * r51210;
        return r51211;
}

↓

double f(double a, double b, double c, double d) {
        double r51212 = a;
        double r51213 = b;
        double r51214 = c;
        double r51215 = r51213 + r51214;
        double r51216 = d;
        double r51217 = r51215 + r51216;
        double r51218 = r51212 + r51217;
        double r51219 = 2.0;
        double r51220 = r51218 * r51219;
        return r51220;
}

Error

Bits error versus a

Bits error versus b

Bits error versus c

Bits error versus d

Target

Original	3.7
Target	3.9
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 2019322 
(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))