Average Error: 0.5 → 0.4
Time: 13.8s
Precision: 64
\[\sqrt{x - 1} \cdot \sqrt{x}\]
↓
\[\left(x - 0.5\right) - \frac{0.125}{x}\]
\sqrt{x - 1} \cdot \sqrt{x}
↓
\left(x - 0.5\right) - \frac{0.125}{x}
double f(double x) {
        double r10145 = x;
        double r10146 = 1.0;
        double r10147 = r10145 - r10146;
        double r10148 = sqrt(r10147);
        double r10149 = sqrt(r10145);
        double r10150 = r10148 * r10149;
        return r10150;
}
↓
double f(double x) {
        double r10151 = x;
        double r10152 = 0.5;
        double r10153 = r10151 - r10152;
        double r10154 = 0.125;
        double r10155 = r10154 / r10151;
        double r10156 = r10153 - r10155;
        return r10156;
}

Error

Bits error versus x

Try it out

Your Program's Arguments

Results

Enter valid numbers for all inputs

Derivation

  1. Initial program 0.5

    \[\sqrt{x - 1} \cdot \sqrt{x}\]

  2. Taylor expanded around inf 0.4

    \[\leadsto \color{blue}{x - \left(0.5 + 0.125 \cdot \frac{1}{x}\right)}\]

  3. Simplified0.4

    \[\leadsto \color{blue}{\left(x - 0.5\right) - \frac{0.125}{x}}\]

  4. Final simplification0.4

    \[\leadsto \left(x - 0.5\right) - \frac{0.125}{x}\]

Reproduce

herbie shell --seed 2019323 +o rules:numerics
(FPCore (x)
  :name "sqrt times"
  :precision binary64
  (* (sqrt (- x 1)) (sqrt x)))