Expanding a square

Percentage Accurate: 54.6% → 100.0%
Time: 2.1s
Alternatives: 3
Speedup: 1.8×

Specification

?
\[\begin{array}{l} \\ \left(x + 1\right) \cdot \left(x + 1\right) - 1 \end{array} \]
(FPCore (x) :precision binary64 (- (* (+ x 1.0) (+ x 1.0)) 1.0))
double code(double x) {
	return ((x + 1.0) * (x + 1.0)) - 1.0;
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = ((x + 1.0d0) * (x + 1.0d0)) - 1.0d0
end function
public static double code(double x) {
	return ((x + 1.0) * (x + 1.0)) - 1.0;
}
def code(x):
	return ((x + 1.0) * (x + 1.0)) - 1.0
function code(x)
	return Float64(Float64(Float64(x + 1.0) * Float64(x + 1.0)) - 1.0)
end
function tmp = code(x)
	tmp = ((x + 1.0) * (x + 1.0)) - 1.0;
end
code[x_] := N[(N[(N[(x + 1.0), $MachinePrecision] * N[(x + 1.0), $MachinePrecision]), $MachinePrecision] - 1.0), $MachinePrecision]
\begin{array}{l}

\\
\left(x + 1\right) \cdot \left(x + 1\right) - 1
\end{array}

Sampling outcomes in binary64 precision:

Local Percentage Accuracy vs ?

The average percentage accuracy by input value. Horizontal axis shows value of an input variable; the variable is choosen in the title. Vertical axis is accuracy; higher is better. Red represent the original program, while blue represents Herbie's suggestion. These can be toggled with buttons below the plot. The line is an average while dots represent individual samples.

Accuracy vs Speed?

Herbie found 3 alternatives:

AlternativeAccuracySpeedup
The accuracy (vertical axis) and speed (horizontal axis) of each alternatives. Up and to the right is better. The red square shows the initial program, and each blue circle shows an alternative.The line shows the best available speed-accuracy tradeoffs.

Initial Program: 54.6% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \left(x + 1\right) \cdot \left(x + 1\right) - 1 \end{array} \]
(FPCore (x) :precision binary64 (- (* (+ x 1.0) (+ x 1.0)) 1.0))
double code(double x) {
	return ((x + 1.0) * (x + 1.0)) - 1.0;
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = ((x + 1.0d0) * (x + 1.0d0)) - 1.0d0
end function
public static double code(double x) {
	return ((x + 1.0) * (x + 1.0)) - 1.0;
}
def code(x):
	return ((x + 1.0) * (x + 1.0)) - 1.0
function code(x)
	return Float64(Float64(Float64(x + 1.0) * Float64(x + 1.0)) - 1.0)
end
function tmp = code(x)
	tmp = ((x + 1.0) * (x + 1.0)) - 1.0;
end
code[x_] := N[(N[(N[(x + 1.0), $MachinePrecision] * N[(x + 1.0), $MachinePrecision]), $MachinePrecision] - 1.0), $MachinePrecision]
\begin{array}{l}

\\
\left(x + 1\right) \cdot \left(x + 1\right) - 1
\end{array}

Alternative 1: 100.0% accurate, 0.1× speedup?

\[\begin{array}{l} \\ \mathsf{fma}\left(x + 1, x, x\right) \end{array} \]
(FPCore (x) :precision binary64 (fma (+ x 1.0) x x))
double code(double x) {
	return fma((x + 1.0), x, x);
}
function code(x)
	return fma(Float64(x + 1.0), x, x)
end
code[x_] := N[(N[(x + 1.0), $MachinePrecision] * x + x), $MachinePrecision]
\begin{array}{l}

\\
\mathsf{fma}\left(x + 1, x, x\right)
\end{array}
Derivation
  1. Initial program 55.9%

    \[\left(x + 1\right) \cdot \left(x + 1\right) - 1 \]
  2. Step-by-step derivation
    1. difference-of-sqr-155.9%

      \[\leadsto \color{blue}{\left(\left(x + 1\right) + 1\right) \cdot \left(\left(x + 1\right) - 1\right)} \]
    2. *-commutative55.9%

      \[\leadsto \color{blue}{\left(\left(x + 1\right) - 1\right) \cdot \left(\left(x + 1\right) + 1\right)} \]
    3. associate--l+100.0%

      \[\leadsto \color{blue}{\left(x + \left(1 - 1\right)\right)} \cdot \left(\left(x + 1\right) + 1\right) \]
    4. metadata-eval100.0%

      \[\leadsto \left(x + \color{blue}{0}\right) \cdot \left(\left(x + 1\right) + 1\right) \]
    5. +-rgt-identity100.0%

      \[\leadsto \color{blue}{x} \cdot \left(\left(x + 1\right) + 1\right) \]
    6. associate-+l+100.0%

      \[\leadsto x \cdot \color{blue}{\left(x + \left(1 + 1\right)\right)} \]
    7. distribute-rgt-in100.0%

      \[\leadsto \color{blue}{x \cdot x + \left(1 + 1\right) \cdot x} \]
    8. sqr-neg100.0%

      \[\leadsto \color{blue}{\left(-x\right) \cdot \left(-x\right)} + \left(1 + 1\right) \cdot x \]
    9. distribute-rgt-neg-out100.0%

      \[\leadsto \color{blue}{\left(-\left(-x\right) \cdot x\right)} + \left(1 + 1\right) \cdot x \]
    10. distribute-lft-neg-in100.0%

      \[\leadsto \color{blue}{\left(-\left(-x\right)\right) \cdot x} + \left(1 + 1\right) \cdot x \]
    11. mul-1-neg100.0%

      \[\leadsto \color{blue}{\left(-1 \cdot \left(-x\right)\right)} \cdot x + \left(1 + 1\right) \cdot x \]
    12. metadata-eval100.0%

      \[\leadsto \left(\color{blue}{\left(-1\right)} \cdot \left(-x\right)\right) \cdot x + \left(1 + 1\right) \cdot x \]
    13. distribute-rgt-out100.0%

      \[\leadsto \color{blue}{x \cdot \left(\left(-1\right) \cdot \left(-x\right) + \left(1 + 1\right)\right)} \]
    14. metadata-eval100.0%

      \[\leadsto x \cdot \left(\color{blue}{-1} \cdot \left(-x\right) + \left(1 + 1\right)\right) \]
    15. mul-1-neg100.0%

      \[\leadsto x \cdot \left(\color{blue}{\left(-\left(-x\right)\right)} + \left(1 + 1\right)\right) \]
    16. metadata-eval100.0%

      \[\leadsto x \cdot \left(\left(-\left(-x\right)\right) + \color{blue}{2}\right) \]
    17. metadata-eval100.0%

      \[\leadsto x \cdot \left(\left(-\left(-x\right)\right) + \color{blue}{\left(--2\right)}\right) \]
    18. metadata-eval100.0%

      \[\leadsto x \cdot \left(\left(-\left(-x\right)\right) + \left(-\color{blue}{\left(-2\right)}\right)\right) \]
    19. metadata-eval100.0%

      \[\leadsto x \cdot \left(\left(-\left(-x\right)\right) + \left(-\left(-\color{blue}{\left(1 + 1\right)}\right)\right)\right) \]
    20. distribute-neg-in100.0%

      \[\leadsto x \cdot \color{blue}{\left(-\left(\left(-x\right) + \left(-\left(1 + 1\right)\right)\right)\right)} \]
    21. distribute-neg-in100.0%

      \[\leadsto x \cdot \left(-\color{blue}{\left(-\left(x + \left(1 + 1\right)\right)\right)}\right) \]
    22. associate-+l+100.0%

      \[\leadsto x \cdot \left(-\left(-\color{blue}{\left(\left(x + 1\right) + 1\right)}\right)\right) \]
    23. mul-1-neg100.0%

      \[\leadsto x \cdot \left(-\color{blue}{-1 \cdot \left(\left(x + 1\right) + 1\right)}\right) \]
    24. metadata-eval100.0%

      \[\leadsto x \cdot \left(-\color{blue}{\left(-1\right)} \cdot \left(\left(x + 1\right) + 1\right)\right) \]
  3. Simplified100.0%

    \[\leadsto \color{blue}{x \cdot \left(x + 2\right)} \]
  4. Step-by-step derivation
    1. *-commutative100.0%

      \[\leadsto \color{blue}{\left(x + 2\right) \cdot x} \]
    2. metadata-eval100.0%

      \[\leadsto \left(x + \color{blue}{\left(1 + 1\right)}\right) \cdot x \]
    3. associate-+l+100.0%

      \[\leadsto \color{blue}{\left(\left(x + 1\right) + 1\right)} \cdot x \]
    4. expm1-log1p-u71.7%

      \[\leadsto \left(\left(x + 1\right) + 1\right) \cdot \color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(x\right)\right)} \]
    5. expm1-udef27.6%

      \[\leadsto \left(\left(x + 1\right) + 1\right) \cdot \color{blue}{\left(e^{\mathsf{log1p}\left(x\right)} - 1\right)} \]
    6. log1p-udef27.6%

      \[\leadsto \left(\left(x + 1\right) + 1\right) \cdot \left(e^{\color{blue}{\log \left(1 + x\right)}} - 1\right) \]
    7. add-exp-log55.9%

      \[\leadsto \left(\left(x + 1\right) + 1\right) \cdot \left(\color{blue}{\left(1 + x\right)} - 1\right) \]
    8. +-commutative55.9%

      \[\leadsto \left(\left(x + 1\right) + 1\right) \cdot \left(\color{blue}{\left(x + 1\right)} - 1\right) \]
    9. difference-of-sqr-155.9%

      \[\leadsto \color{blue}{\left(x + 1\right) \cdot \left(x + 1\right) - 1} \]
    10. distribute-lft1-in55.9%

      \[\leadsto \color{blue}{\left(x \cdot \left(x + 1\right) + \left(x + 1\right)\right)} - 1 \]
    11. associate--l+62.1%

      \[\leadsto \color{blue}{x \cdot \left(x + 1\right) + \left(\left(x + 1\right) - 1\right)} \]
    12. add-exp-log34.7%

      \[\leadsto x \cdot \left(x + 1\right) + \left(\color{blue}{e^{\log \left(x + 1\right)}} - 1\right) \]
    13. +-commutative34.7%

      \[\leadsto x \cdot \left(x + 1\right) + \left(e^{\log \color{blue}{\left(1 + x\right)}} - 1\right) \]
    14. log1p-udef34.7%

      \[\leadsto x \cdot \left(x + 1\right) + \left(e^{\color{blue}{\mathsf{log1p}\left(x\right)}} - 1\right) \]
    15. expm1-udef72.7%

      \[\leadsto x \cdot \left(x + 1\right) + \color{blue}{\mathsf{expm1}\left(\mathsf{log1p}\left(x\right)\right)} \]
    16. expm1-log1p-u100.0%

      \[\leadsto x \cdot \left(x + 1\right) + \color{blue}{x} \]
    17. *-commutative100.0%

      \[\leadsto \color{blue}{\left(x + 1\right) \cdot x} + x \]
    18. fma-def100.0%

      \[\leadsto \color{blue}{\mathsf{fma}\left(x + 1, x, x\right)} \]
  5. Applied egg-rr100.0%

    \[\leadsto \color{blue}{\mathsf{fma}\left(x + 1, x, x\right)} \]
  6. Final simplification100.0%

    \[\leadsto \mathsf{fma}\left(x + 1, x, x\right) \]

Alternative 2: 100.0% accurate, 1.8× speedup?

\[\begin{array}{l} \\ x \cdot \left(x + 2\right) \end{array} \]
(FPCore (x) :precision binary64 (* x (+ x 2.0)))
double code(double x) {
	return x * (x + 2.0);
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = x * (x + 2.0d0)
end function
public static double code(double x) {
	return x * (x + 2.0);
}
def code(x):
	return x * (x + 2.0)
function code(x)
	return Float64(x * Float64(x + 2.0))
end
function tmp = code(x)
	tmp = x * (x + 2.0);
end
code[x_] := N[(x * N[(x + 2.0), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}

\\
x \cdot \left(x + 2\right)
\end{array}
Derivation
  1. Initial program 55.9%

    \[\left(x + 1\right) \cdot \left(x + 1\right) - 1 \]
  2. Step-by-step derivation
    1. difference-of-sqr-155.9%

      \[\leadsto \color{blue}{\left(\left(x + 1\right) + 1\right) \cdot \left(\left(x + 1\right) - 1\right)} \]
    2. *-commutative55.9%

      \[\leadsto \color{blue}{\left(\left(x + 1\right) - 1\right) \cdot \left(\left(x + 1\right) + 1\right)} \]
    3. associate--l+100.0%

      \[\leadsto \color{blue}{\left(x + \left(1 - 1\right)\right)} \cdot \left(\left(x + 1\right) + 1\right) \]
    4. metadata-eval100.0%

      \[\leadsto \left(x + \color{blue}{0}\right) \cdot \left(\left(x + 1\right) + 1\right) \]
    5. +-rgt-identity100.0%

      \[\leadsto \color{blue}{x} \cdot \left(\left(x + 1\right) + 1\right) \]
    6. associate-+l+100.0%

      \[\leadsto x \cdot \color{blue}{\left(x + \left(1 + 1\right)\right)} \]
    7. distribute-rgt-in100.0%

      \[\leadsto \color{blue}{x \cdot x + \left(1 + 1\right) \cdot x} \]
    8. sqr-neg100.0%

      \[\leadsto \color{blue}{\left(-x\right) \cdot \left(-x\right)} + \left(1 + 1\right) \cdot x \]
    9. distribute-rgt-neg-out100.0%

      \[\leadsto \color{blue}{\left(-\left(-x\right) \cdot x\right)} + \left(1 + 1\right) \cdot x \]
    10. distribute-lft-neg-in100.0%

      \[\leadsto \color{blue}{\left(-\left(-x\right)\right) \cdot x} + \left(1 + 1\right) \cdot x \]
    11. mul-1-neg100.0%

      \[\leadsto \color{blue}{\left(-1 \cdot \left(-x\right)\right)} \cdot x + \left(1 + 1\right) \cdot x \]
    12. metadata-eval100.0%

      \[\leadsto \left(\color{blue}{\left(-1\right)} \cdot \left(-x\right)\right) \cdot x + \left(1 + 1\right) \cdot x \]
    13. distribute-rgt-out100.0%

      \[\leadsto \color{blue}{x \cdot \left(\left(-1\right) \cdot \left(-x\right) + \left(1 + 1\right)\right)} \]
    14. metadata-eval100.0%

      \[\leadsto x \cdot \left(\color{blue}{-1} \cdot \left(-x\right) + \left(1 + 1\right)\right) \]
    15. mul-1-neg100.0%

      \[\leadsto x \cdot \left(\color{blue}{\left(-\left(-x\right)\right)} + \left(1 + 1\right)\right) \]
    16. metadata-eval100.0%

      \[\leadsto x \cdot \left(\left(-\left(-x\right)\right) + \color{blue}{2}\right) \]
    17. metadata-eval100.0%

      \[\leadsto x \cdot \left(\left(-\left(-x\right)\right) + \color{blue}{\left(--2\right)}\right) \]
    18. metadata-eval100.0%

      \[\leadsto x \cdot \left(\left(-\left(-x\right)\right) + \left(-\color{blue}{\left(-2\right)}\right)\right) \]
    19. metadata-eval100.0%

      \[\leadsto x \cdot \left(\left(-\left(-x\right)\right) + \left(-\left(-\color{blue}{\left(1 + 1\right)}\right)\right)\right) \]
    20. distribute-neg-in100.0%

      \[\leadsto x \cdot \color{blue}{\left(-\left(\left(-x\right) + \left(-\left(1 + 1\right)\right)\right)\right)} \]
    21. distribute-neg-in100.0%

      \[\leadsto x \cdot \left(-\color{blue}{\left(-\left(x + \left(1 + 1\right)\right)\right)}\right) \]
    22. associate-+l+100.0%

      \[\leadsto x \cdot \left(-\left(-\color{blue}{\left(\left(x + 1\right) + 1\right)}\right)\right) \]
    23. mul-1-neg100.0%

      \[\leadsto x \cdot \left(-\color{blue}{-1 \cdot \left(\left(x + 1\right) + 1\right)}\right) \]
    24. metadata-eval100.0%

      \[\leadsto x \cdot \left(-\color{blue}{\left(-1\right)} \cdot \left(\left(x + 1\right) + 1\right)\right) \]
  3. Simplified100.0%

    \[\leadsto \color{blue}{x \cdot \left(x + 2\right)} \]
  4. Final simplification100.0%

    \[\leadsto x \cdot \left(x + 2\right) \]

Alternative 3: 50.5% accurate, 3.0× speedup?

\[\begin{array}{l} \\ x \cdot 2 \end{array} \]
(FPCore (x) :precision binary64 (* x 2.0))
double code(double x) {
	return x * 2.0;
}
real(8) function code(x)
    real(8), intent (in) :: x
    code = x * 2.0d0
end function
public static double code(double x) {
	return x * 2.0;
}
def code(x):
	return x * 2.0
function code(x)
	return Float64(x * 2.0)
end
function tmp = code(x)
	tmp = x * 2.0;
end
code[x_] := N[(x * 2.0), $MachinePrecision]
\begin{array}{l}

\\
x \cdot 2
\end{array}
Derivation
  1. Initial program 55.9%

    \[\left(x + 1\right) \cdot \left(x + 1\right) - 1 \]
  2. Step-by-step derivation
    1. difference-of-sqr-155.9%

      \[\leadsto \color{blue}{\left(\left(x + 1\right) + 1\right) \cdot \left(\left(x + 1\right) - 1\right)} \]
    2. *-commutative55.9%

      \[\leadsto \color{blue}{\left(\left(x + 1\right) - 1\right) \cdot \left(\left(x + 1\right) + 1\right)} \]
    3. associate--l+100.0%

      \[\leadsto \color{blue}{\left(x + \left(1 - 1\right)\right)} \cdot \left(\left(x + 1\right) + 1\right) \]
    4. metadata-eval100.0%

      \[\leadsto \left(x + \color{blue}{0}\right) \cdot \left(\left(x + 1\right) + 1\right) \]
    5. +-rgt-identity100.0%

      \[\leadsto \color{blue}{x} \cdot \left(\left(x + 1\right) + 1\right) \]
    6. associate-+l+100.0%

      \[\leadsto x \cdot \color{blue}{\left(x + \left(1 + 1\right)\right)} \]
    7. distribute-rgt-in100.0%

      \[\leadsto \color{blue}{x \cdot x + \left(1 + 1\right) \cdot x} \]
    8. sqr-neg100.0%

      \[\leadsto \color{blue}{\left(-x\right) \cdot \left(-x\right)} + \left(1 + 1\right) \cdot x \]
    9. distribute-rgt-neg-out100.0%

      \[\leadsto \color{blue}{\left(-\left(-x\right) \cdot x\right)} + \left(1 + 1\right) \cdot x \]
    10. distribute-lft-neg-in100.0%

      \[\leadsto \color{blue}{\left(-\left(-x\right)\right) \cdot x} + \left(1 + 1\right) \cdot x \]
    11. mul-1-neg100.0%

      \[\leadsto \color{blue}{\left(-1 \cdot \left(-x\right)\right)} \cdot x + \left(1 + 1\right) \cdot x \]
    12. metadata-eval100.0%

      \[\leadsto \left(\color{blue}{\left(-1\right)} \cdot \left(-x\right)\right) \cdot x + \left(1 + 1\right) \cdot x \]
    13. distribute-rgt-out100.0%

      \[\leadsto \color{blue}{x \cdot \left(\left(-1\right) \cdot \left(-x\right) + \left(1 + 1\right)\right)} \]
    14. metadata-eval100.0%

      \[\leadsto x \cdot \left(\color{blue}{-1} \cdot \left(-x\right) + \left(1 + 1\right)\right) \]
    15. mul-1-neg100.0%

      \[\leadsto x \cdot \left(\color{blue}{\left(-\left(-x\right)\right)} + \left(1 + 1\right)\right) \]
    16. metadata-eval100.0%

      \[\leadsto x \cdot \left(\left(-\left(-x\right)\right) + \color{blue}{2}\right) \]
    17. metadata-eval100.0%

      \[\leadsto x \cdot \left(\left(-\left(-x\right)\right) + \color{blue}{\left(--2\right)}\right) \]
    18. metadata-eval100.0%

      \[\leadsto x \cdot \left(\left(-\left(-x\right)\right) + \left(-\color{blue}{\left(-2\right)}\right)\right) \]
    19. metadata-eval100.0%

      \[\leadsto x \cdot \left(\left(-\left(-x\right)\right) + \left(-\left(-\color{blue}{\left(1 + 1\right)}\right)\right)\right) \]
    20. distribute-neg-in100.0%

      \[\leadsto x \cdot \color{blue}{\left(-\left(\left(-x\right) + \left(-\left(1 + 1\right)\right)\right)\right)} \]
    21. distribute-neg-in100.0%

      \[\leadsto x \cdot \left(-\color{blue}{\left(-\left(x + \left(1 + 1\right)\right)\right)}\right) \]
    22. associate-+l+100.0%

      \[\leadsto x \cdot \left(-\left(-\color{blue}{\left(\left(x + 1\right) + 1\right)}\right)\right) \]
    23. mul-1-neg100.0%

      \[\leadsto x \cdot \left(-\color{blue}{-1 \cdot \left(\left(x + 1\right) + 1\right)}\right) \]
    24. metadata-eval100.0%

      \[\leadsto x \cdot \left(-\color{blue}{\left(-1\right)} \cdot \left(\left(x + 1\right) + 1\right)\right) \]
  3. Simplified100.0%

    \[\leadsto \color{blue}{x \cdot \left(x + 2\right)} \]
  4. Taylor expanded in x around 0 49.1%

    \[\leadsto \color{blue}{2 \cdot x} \]
  5. Final simplification49.1%

    \[\leadsto x \cdot 2 \]

Reproduce

?
herbie shell --seed 2023333 
(FPCore (x)
  :name "Expanding a square"
  :precision binary64
  (- (* (+ x 1.0) (+ x 1.0)) 1.0))