
(FPCore (v) :precision binary64 (acos (/ (- 1.0 (* 5.0 (* v v))) (- (* v v) 1.0))))
double code(double v) {
return acos(((1.0 - (5.0 * (v * v))) / ((v * v) - 1.0)));
}
real(8) function code(v)
real(8), intent (in) :: v
code = acos(((1.0d0 - (5.0d0 * (v * v))) / ((v * v) - 1.0d0)))
end function
public static double code(double v) {
return Math.acos(((1.0 - (5.0 * (v * v))) / ((v * v) - 1.0)));
}
def code(v): return math.acos(((1.0 - (5.0 * (v * v))) / ((v * v) - 1.0)))
function code(v) return acos(Float64(Float64(1.0 - Float64(5.0 * Float64(v * v))) / Float64(Float64(v * v) - 1.0))) end
function tmp = code(v) tmp = acos(((1.0 - (5.0 * (v * v))) / ((v * v) - 1.0))); end
code[v_] := N[ArcCos[N[(N[(1.0 - N[(5.0 * N[(v * v), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(N[(v * v), $MachinePrecision] - 1.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}
\\
\cos^{-1} \left(\frac{1 - 5 \cdot \left(v \cdot v\right)}{v \cdot v - 1}\right)
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 5 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (v) :precision binary64 (acos (/ (- 1.0 (* 5.0 (* v v))) (- (* v v) 1.0))))
double code(double v) {
return acos(((1.0 - (5.0 * (v * v))) / ((v * v) - 1.0)));
}
real(8) function code(v)
real(8), intent (in) :: v
code = acos(((1.0d0 - (5.0d0 * (v * v))) / ((v * v) - 1.0d0)))
end function
public static double code(double v) {
return Math.acos(((1.0 - (5.0 * (v * v))) / ((v * v) - 1.0)));
}
def code(v): return math.acos(((1.0 - (5.0 * (v * v))) / ((v * v) - 1.0)))
function code(v) return acos(Float64(Float64(1.0 - Float64(5.0 * Float64(v * v))) / Float64(Float64(v * v) - 1.0))) end
function tmp = code(v) tmp = acos(((1.0 - (5.0 * (v * v))) / ((v * v) - 1.0))); end
code[v_] := N[ArcCos[N[(N[(1.0 - N[(5.0 * N[(v * v), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(N[(v * v), $MachinePrecision] - 1.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}
\\
\cos^{-1} \left(\frac{1 - 5 \cdot \left(v \cdot v\right)}{v \cdot v - 1}\right)
\end{array}
(FPCore (v) :precision binary64 (acos (/ (fma v (* v -5.0) 1.0) (fma v v -1.0))))
double code(double v) {
return acos((fma(v, (v * -5.0), 1.0) / fma(v, v, -1.0)));
}
function code(v) return acos(Float64(fma(v, Float64(v * -5.0), 1.0) / fma(v, v, -1.0))) end
code[v_] := N[ArcCos[N[(N[(v * N[(v * -5.0), $MachinePrecision] + 1.0), $MachinePrecision] / N[(v * v + -1.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}
\\
\cos^{-1} \left(\frac{\mathsf{fma}\left(v, v \cdot -5, 1\right)}{\mathsf{fma}\left(v, v, -1\right)}\right)
\end{array}
Initial program 99.3%
lift--.f64N/A
sub-negN/A
+-commutativeN/A
lift-*.f64N/A
lift-*.f64N/A
associate-*r*N/A
*-commutativeN/A
distribute-rgt-neg-inN/A
lower-fma.f64N/A
*-commutativeN/A
distribute-rgt-neg-inN/A
lower-*.f64N/A
metadata-eval99.3
lift--.f64N/A
sub-negN/A
lift-*.f64N/A
lower-fma.f64N/A
metadata-eval99.3
Applied rewrites99.3%
(FPCore (v) :precision binary64 (acos (fma v (* v (fma (* v v) 4.0 4.0)) -1.0)))
double code(double v) {
return acos(fma(v, (v * fma((v * v), 4.0, 4.0)), -1.0));
}
function code(v) return acos(fma(v, Float64(v * fma(Float64(v * v), 4.0, 4.0)), -1.0)) end
code[v_] := N[ArcCos[N[(v * N[(v * N[(N[(v * v), $MachinePrecision] * 4.0 + 4.0), $MachinePrecision]), $MachinePrecision] + -1.0), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}
\\
\cos^{-1} \left(\mathsf{fma}\left(v, v \cdot \mathsf{fma}\left(v \cdot v, 4, 4\right), -1\right)\right)
\end{array}
Initial program 99.3%
Taylor expanded in v around 0
sub-negN/A
unpow2N/A
associate-*l*N/A
*-commutativeN/A
metadata-evalN/A
lower-fma.f64N/A
*-commutativeN/A
lower-*.f64N/A
+-commutativeN/A
*-commutativeN/A
lower-fma.f64N/A
unpow2N/A
lower-*.f6498.9
Applied rewrites98.9%
(FPCore (v) :precision binary64 (fma PI 0.5 (- (asin (fma v (* v 4.0) -1.0)))))
double code(double v) {
return fma(((double) M_PI), 0.5, -asin(fma(v, (v * 4.0), -1.0)));
}
function code(v) return fma(pi, 0.5, Float64(-asin(fma(v, Float64(v * 4.0), -1.0)))) end
code[v_] := N[(Pi * 0.5 + (-N[ArcSin[N[(v * N[(v * 4.0), $MachinePrecision] + -1.0), $MachinePrecision]], $MachinePrecision])), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(\pi, 0.5, -\sin^{-1} \left(\mathsf{fma}\left(v, v \cdot 4, -1\right)\right)\right)
\end{array}
Initial program 99.3%
Taylor expanded in v around 0
sub-negN/A
unpow2N/A
associate-*r*N/A
*-commutativeN/A
metadata-evalN/A
lower-fma.f64N/A
*-commutativeN/A
lower-*.f6498.7
Applied rewrites98.7%
lift-acos.f64N/A
acos-asinN/A
lift-PI.f64N/A
div-invN/A
metadata-evalN/A
lift-*.f64N/A
sub-negN/A
lift-*.f64N/A
lower-fma.f64N/A
lower-neg.f64N/A
lower-asin.f6498.7
Applied rewrites98.7%
(FPCore (v) :precision binary64 (acos (fma v (* v 4.0) -1.0)))
double code(double v) {
return acos(fma(v, (v * 4.0), -1.0));
}
function code(v) return acos(fma(v, Float64(v * 4.0), -1.0)) end
code[v_] := N[ArcCos[N[(v * N[(v * 4.0), $MachinePrecision] + -1.0), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}
\\
\cos^{-1} \left(\mathsf{fma}\left(v, v \cdot 4, -1\right)\right)
\end{array}
Initial program 99.3%
Taylor expanded in v around 0
sub-negN/A
unpow2N/A
associate-*r*N/A
*-commutativeN/A
metadata-evalN/A
lower-fma.f64N/A
*-commutativeN/A
lower-*.f6498.7
Applied rewrites98.7%
(FPCore (v) :precision binary64 (acos -1.0))
double code(double v) {
return acos(-1.0);
}
real(8) function code(v)
real(8), intent (in) :: v
code = acos((-1.0d0))
end function
public static double code(double v) {
return Math.acos(-1.0);
}
def code(v): return math.acos(-1.0)
function code(v) return acos(-1.0) end
function tmp = code(v) tmp = acos(-1.0); end
code[v_] := N[ArcCos[-1.0], $MachinePrecision]
\begin{array}{l}
\\
\cos^{-1} -1
\end{array}
Initial program 99.3%
Taylor expanded in v around 0
Applied rewrites97.9%
herbie shell --seed 2024223
(FPCore (v)
:name "Falkner and Boettcher, Appendix B, 1"
:precision binary64
(acos (/ (- 1.0 (* 5.0 (* v v))) (- (* v v) 1.0))))