
(FPCore (a b c d) :precision binary64 (/ (- (* b c) (* a d)) (+ (* c c) (* d d))))
double code(double a, double b, double c, double d) {
return ((b * c) - (a * d)) / ((c * c) + (d * d));
}
real(8) function code(a, b, c, d)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
real(8), intent (in) :: d
code = ((b * c) - (a * d)) / ((c * c) + (d * d))
end function
public static double code(double a, double b, double c, double d) {
return ((b * c) - (a * d)) / ((c * c) + (d * d));
}
def code(a, b, c, d): return ((b * c) - (a * d)) / ((c * c) + (d * d))
function code(a, b, c, d) return Float64(Float64(Float64(b * c) - Float64(a * d)) / Float64(Float64(c * c) + Float64(d * d))) end
function tmp = code(a, b, c, d) tmp = ((b * c) - (a * d)) / ((c * c) + (d * d)); end
code[a_, b_, c_, d_] := N[(N[(N[(b * c), $MachinePrecision] - N[(a * d), $MachinePrecision]), $MachinePrecision] / N[(N[(c * c), $MachinePrecision] + N[(d * d), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{b \cdot c - a \cdot d}{c \cdot c + d \cdot d}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 8 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (a b c d) :precision binary64 (/ (- (* b c) (* a d)) (+ (* c c) (* d d))))
double code(double a, double b, double c, double d) {
return ((b * c) - (a * d)) / ((c * c) + (d * d));
}
real(8) function code(a, b, c, d)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
real(8), intent (in) :: d
code = ((b * c) - (a * d)) / ((c * c) + (d * d))
end function
public static double code(double a, double b, double c, double d) {
return ((b * c) - (a * d)) / ((c * c) + (d * d));
}
def code(a, b, c, d): return ((b * c) - (a * d)) / ((c * c) + (d * d))
function code(a, b, c, d) return Float64(Float64(Float64(b * c) - Float64(a * d)) / Float64(Float64(c * c) + Float64(d * d))) end
function tmp = code(a, b, c, d) tmp = ((b * c) - (a * d)) / ((c * c) + (d * d)); end
code[a_, b_, c_, d_] := N[(N[(N[(b * c), $MachinePrecision] - N[(a * d), $MachinePrecision]), $MachinePrecision] / N[(N[(c * c), $MachinePrecision] + N[(d * d), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{b \cdot c - a \cdot d}{c \cdot c + d \cdot d}
\end{array}
(FPCore (a b c d)
:precision binary64
(let* ((t_0 (/ (fma c (/ b d) (- a)) d)))
(if (<= d -3e+118)
t_0
(if (<= d -1.12e-138)
(/ (- (* b c) (* d a)) (+ (* c c) (* d d)))
(if (<= d 0.28) (/ (fma a (- (/ d c)) b) c) t_0)))))
double code(double a, double b, double c, double d) {
double t_0 = fma(c, (b / d), -a) / d;
double tmp;
if (d <= -3e+118) {
tmp = t_0;
} else if (d <= -1.12e-138) {
tmp = ((b * c) - (d * a)) / ((c * c) + (d * d));
} else if (d <= 0.28) {
tmp = fma(a, -(d / c), b) / c;
} else {
tmp = t_0;
}
return tmp;
}
function code(a, b, c, d) t_0 = Float64(fma(c, Float64(b / d), Float64(-a)) / d) tmp = 0.0 if (d <= -3e+118) tmp = t_0; elseif (d <= -1.12e-138) tmp = Float64(Float64(Float64(b * c) - Float64(d * a)) / Float64(Float64(c * c) + Float64(d * d))); elseif (d <= 0.28) tmp = Float64(fma(a, Float64(-Float64(d / c)), b) / c); else tmp = t_0; end return tmp end
code[a_, b_, c_, d_] := Block[{t$95$0 = N[(N[(c * N[(b / d), $MachinePrecision] + (-a)), $MachinePrecision] / d), $MachinePrecision]}, If[LessEqual[d, -3e+118], t$95$0, If[LessEqual[d, -1.12e-138], N[(N[(N[(b * c), $MachinePrecision] - N[(d * a), $MachinePrecision]), $MachinePrecision] / N[(N[(c * c), $MachinePrecision] + N[(d * d), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], If[LessEqual[d, 0.28], N[(N[(a * (-N[(d / c), $MachinePrecision]) + b), $MachinePrecision] / c), $MachinePrecision], t$95$0]]]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{\mathsf{fma}\left(c, \frac{b}{d}, -a\right)}{d}\\
\mathbf{if}\;d \leq -3 \cdot 10^{+118}:\\
\;\;\;\;t\_0\\
\mathbf{elif}\;d \leq -1.12 \cdot 10^{-138}:\\
\;\;\;\;\frac{b \cdot c - d \cdot a}{c \cdot c + d \cdot d}\\
\mathbf{elif}\;d \leq 0.28:\\
\;\;\;\;\frac{\mathsf{fma}\left(a, -\frac{d}{c}, b\right)}{c}\\
\mathbf{else}:\\
\;\;\;\;t\_0\\
\end{array}
\end{array}
if d < -3e118 or 0.28000000000000003 < d Initial program 39.8%
Taylor expanded in c around 0
+-commutativeN/A
mul-1-negN/A
unsub-negN/A
unpow2N/A
associate-/r*N/A
div-subN/A
lower-/.f64N/A
sub-negN/A
*-commutativeN/A
associate-/l*N/A
mul-1-negN/A
lower-fma.f64N/A
lower-/.f64N/A
mul-1-negN/A
lower-neg.f6481.8
Applied rewrites81.8%
if -3e118 < d < -1.1199999999999999e-138Initial program 84.9%
if -1.1199999999999999e-138 < d < 0.28000000000000003Initial program 65.2%
Taylor expanded in c around 0
mul-1-negN/A
distribute-neg-frac2N/A
mul-1-negN/A
lower-/.f64N/A
mul-1-negN/A
lower-neg.f6414.9
Applied rewrites14.9%
Taylor expanded in c around inf
lower-/.f64N/A
+-commutativeN/A
mul-1-negN/A
associate-/l*N/A
distribute-rgt-neg-inN/A
mul-1-negN/A
lower-fma.f64N/A
mul-1-negN/A
distribute-neg-frac2N/A
mul-1-negN/A
lower-/.f64N/A
mul-1-negN/A
lower-neg.f6486.8
Applied rewrites86.8%
Final simplification84.4%
(FPCore (a b c d)
:precision binary64
(let* ((t_0 (- (/ a d))) (t_1 (/ (- (* b c) (* d a)) (* d d))))
(if (<= d -9.5e+139)
t_0
(if (<= d -3.3e-76)
t_1
(if (<= d 0.28)
(/ (- b (/ (* d a) c)) c)
(if (<= d 1e+102) t_1 t_0))))))
double code(double a, double b, double c, double d) {
double t_0 = -(a / d);
double t_1 = ((b * c) - (d * a)) / (d * d);
double tmp;
if (d <= -9.5e+139) {
tmp = t_0;
} else if (d <= -3.3e-76) {
tmp = t_1;
} else if (d <= 0.28) {
tmp = (b - ((d * a) / c)) / c;
} else if (d <= 1e+102) {
tmp = t_1;
} else {
tmp = t_0;
}
return tmp;
}
real(8) function code(a, b, c, d)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
real(8), intent (in) :: d
real(8) :: t_0
real(8) :: t_1
real(8) :: tmp
t_0 = -(a / d)
t_1 = ((b * c) - (d * a)) / (d * d)
if (d <= (-9.5d+139)) then
tmp = t_0
else if (d <= (-3.3d-76)) then
tmp = t_1
else if (d <= 0.28d0) then
tmp = (b - ((d * a) / c)) / c
else if (d <= 1d+102) then
tmp = t_1
else
tmp = t_0
end if
code = tmp
end function
public static double code(double a, double b, double c, double d) {
double t_0 = -(a / d);
double t_1 = ((b * c) - (d * a)) / (d * d);
double tmp;
if (d <= -9.5e+139) {
tmp = t_0;
} else if (d <= -3.3e-76) {
tmp = t_1;
} else if (d <= 0.28) {
tmp = (b - ((d * a) / c)) / c;
} else if (d <= 1e+102) {
tmp = t_1;
} else {
tmp = t_0;
}
return tmp;
}
def code(a, b, c, d): t_0 = -(a / d) t_1 = ((b * c) - (d * a)) / (d * d) tmp = 0 if d <= -9.5e+139: tmp = t_0 elif d <= -3.3e-76: tmp = t_1 elif d <= 0.28: tmp = (b - ((d * a) / c)) / c elif d <= 1e+102: tmp = t_1 else: tmp = t_0 return tmp
function code(a, b, c, d) t_0 = Float64(-Float64(a / d)) t_1 = Float64(Float64(Float64(b * c) - Float64(d * a)) / Float64(d * d)) tmp = 0.0 if (d <= -9.5e+139) tmp = t_0; elseif (d <= -3.3e-76) tmp = t_1; elseif (d <= 0.28) tmp = Float64(Float64(b - Float64(Float64(d * a) / c)) / c); elseif (d <= 1e+102) tmp = t_1; else tmp = t_0; end return tmp end
function tmp_2 = code(a, b, c, d) t_0 = -(a / d); t_1 = ((b * c) - (d * a)) / (d * d); tmp = 0.0; if (d <= -9.5e+139) tmp = t_0; elseif (d <= -3.3e-76) tmp = t_1; elseif (d <= 0.28) tmp = (b - ((d * a) / c)) / c; elseif (d <= 1e+102) tmp = t_1; else tmp = t_0; end tmp_2 = tmp; end
code[a_, b_, c_, d_] := Block[{t$95$0 = (-N[(a / d), $MachinePrecision])}, Block[{t$95$1 = N[(N[(N[(b * c), $MachinePrecision] - N[(d * a), $MachinePrecision]), $MachinePrecision] / N[(d * d), $MachinePrecision]), $MachinePrecision]}, If[LessEqual[d, -9.5e+139], t$95$0, If[LessEqual[d, -3.3e-76], t$95$1, If[LessEqual[d, 0.28], N[(N[(b - N[(N[(d * a), $MachinePrecision] / c), $MachinePrecision]), $MachinePrecision] / c), $MachinePrecision], If[LessEqual[d, 1e+102], t$95$1, t$95$0]]]]]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := -\frac{a}{d}\\
t_1 := \frac{b \cdot c - d \cdot a}{d \cdot d}\\
\mathbf{if}\;d \leq -9.5 \cdot 10^{+139}:\\
\;\;\;\;t\_0\\
\mathbf{elif}\;d \leq -3.3 \cdot 10^{-76}:\\
\;\;\;\;t\_1\\
\mathbf{elif}\;d \leq 0.28:\\
\;\;\;\;\frac{b - \frac{d \cdot a}{c}}{c}\\
\mathbf{elif}\;d \leq 10^{+102}:\\
\;\;\;\;t\_1\\
\mathbf{else}:\\
\;\;\;\;t\_0\\
\end{array}
\end{array}
if d < -9.5000000000000002e139 or 9.99999999999999977e101 < d Initial program 35.2%
Taylor expanded in c around 0
mul-1-negN/A
distribute-neg-frac2N/A
mul-1-negN/A
lower-/.f64N/A
mul-1-negN/A
lower-neg.f6474.6
Applied rewrites74.6%
if -9.5000000000000002e139 < d < -3.29999999999999984e-76 or 0.28000000000000003 < d < 9.99999999999999977e101Initial program 74.3%
Taylor expanded in c around 0
unpow2N/A
lower-*.f6452.6
Applied rewrites52.6%
if -3.29999999999999984e-76 < d < 0.28000000000000003Initial program 73.3%
Taylor expanded in c around inf
lower-/.f64N/A
mul-1-negN/A
unsub-negN/A
lower--.f64N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f6482.5
Applied rewrites82.5%
Final simplification72.5%
(FPCore (a b c d) :precision binary64 (if (< (fabs d) (fabs c)) (/ (- b (* a (/ d c))) (+ c (* d (/ d c)))) (/ (+ (- a) (* b (/ c d))) (+ d (* c (/ c d))))))
double code(double a, double b, double c, double d) {
double tmp;
if (fabs(d) < fabs(c)) {
tmp = (b - (a * (d / c))) / (c + (d * (d / c)));
} else {
tmp = (-a + (b * (c / d))) / (d + (c * (c / d)));
}
return tmp;
}
real(8) function code(a, b, c, d)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
real(8), intent (in) :: d
real(8) :: tmp
if (abs(d) < abs(c)) then
tmp = (b - (a * (d / c))) / (c + (d * (d / c)))
else
tmp = (-a + (b * (c / d))) / (d + (c * (c / d)))
end if
code = tmp
end function
public static double code(double a, double b, double c, double d) {
double tmp;
if (Math.abs(d) < Math.abs(c)) {
tmp = (b - (a * (d / c))) / (c + (d * (d / c)));
} else {
tmp = (-a + (b * (c / d))) / (d + (c * (c / d)));
}
return tmp;
}
def code(a, b, c, d): tmp = 0 if math.fabs(d) < math.fabs(c): tmp = (b - (a * (d / c))) / (c + (d * (d / c))) else: tmp = (-a + (b * (c / d))) / (d + (c * (c / d))) return tmp
function code(a, b, c, d) tmp = 0.0 if (abs(d) < abs(c)) tmp = Float64(Float64(b - Float64(a * Float64(d / c))) / Float64(c + Float64(d * Float64(d / c)))); else tmp = Float64(Float64(Float64(-a) + Float64(b * Float64(c / d))) / Float64(d + Float64(c * Float64(c / d)))); end return tmp end
function tmp_2 = code(a, b, c, d) tmp = 0.0; if (abs(d) < abs(c)) tmp = (b - (a * (d / c))) / (c + (d * (d / c))); else tmp = (-a + (b * (c / d))) / (d + (c * (c / d))); end tmp_2 = tmp; end
code[a_, b_, c_, d_] := If[Less[N[Abs[d], $MachinePrecision], N[Abs[c], $MachinePrecision]], N[(N[(b - N[(a * N[(d / c), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(c + N[(d * N[(d / c), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(N[((-a) + N[(b * N[(c / d), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / N[(d + N[(c * N[(c / d), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\left|d\right| < \left|c\right|:\\
\;\;\;\;\frac{b - a \cdot \frac{d}{c}}{c + d \cdot \frac{d}{c}}\\
\mathbf{else}:\\
\;\;\;\;\frac{\left(-a\right) + b \cdot \frac{c}{d}}{d + c \cdot \frac{c}{d}}\\
\end{array}
\end{array}
herbie shell --seed 2024228
(FPCore (a b c d)
:name "Complex division, imag part"
:precision binary64
:alt
(! :herbie-platform default (if (< (fabs d) (fabs c)) (/ (- b (* a (/ d c))) (+ c (* d (/ d c)))) (/ (+ (- a) (* b (/ c d))) (+ d (* c (/ c d))))))
(/ (- (* b c) (* a d)) (+ (* c c) (* d d))))