
(FPCore (x y z t) :precision binary64 (- x (/ (log (+ (- 1.0 y) (* y (exp z)))) t)))
double code(double x, double y, double z, double t) {
return x - (log(((1.0 - y) + (y * exp(z)))) / t);
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
code = x - (log(((1.0d0 - y) + (y * exp(z)))) / t)
end function
public static double code(double x, double y, double z, double t) {
return x - (Math.log(((1.0 - y) + (y * Math.exp(z)))) / t);
}
def code(x, y, z, t): return x - (math.log(((1.0 - y) + (y * math.exp(z)))) / t)
function code(x, y, z, t) return Float64(x - Float64(log(Float64(Float64(1.0 - y) + Float64(y * exp(z)))) / t)) end
function tmp = code(x, y, z, t) tmp = x - (log(((1.0 - y) + (y * exp(z)))) / t); end
code[x_, y_, z_, t_] := N[(x - N[(N[Log[N[(N[(1.0 - y), $MachinePrecision] + N[(y * N[Exp[z], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] / t), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
x - \frac{\log \left(\left(1 - y\right) + y \cdot e^{z}\right)}{t}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 5 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (x y z t) :precision binary64 (- x (/ (log (+ (- 1.0 y) (* y (exp z)))) t)))
double code(double x, double y, double z, double t) {
return x - (log(((1.0 - y) + (y * exp(z)))) / t);
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
code = x - (log(((1.0d0 - y) + (y * exp(z)))) / t)
end function
public static double code(double x, double y, double z, double t) {
return x - (Math.log(((1.0 - y) + (y * Math.exp(z)))) / t);
}
def code(x, y, z, t): return x - (math.log(((1.0 - y) + (y * math.exp(z)))) / t)
function code(x, y, z, t) return Float64(x - Float64(log(Float64(Float64(1.0 - y) + Float64(y * exp(z)))) / t)) end
function tmp = code(x, y, z, t) tmp = x - (log(((1.0 - y) + (y * exp(z)))) / t); end
code[x_, y_, z_, t_] := N[(x - N[(N[Log[N[(N[(1.0 - y), $MachinePrecision] + N[(y * N[Exp[z], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] / t), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
x - \frac{\log \left(\left(1 - y\right) + y \cdot e^{z}\right)}{t}
\end{array}
(FPCore (x y z t) :precision binary64 (- x (/ (log1p (* y (expm1 z))) t)))
double code(double x, double y, double z, double t) {
return x - (log1p((y * expm1(z))) / t);
}
public static double code(double x, double y, double z, double t) {
return x - (Math.log1p((y * Math.expm1(z))) / t);
}
def code(x, y, z, t): return x - (math.log1p((y * math.expm1(z))) / t)
function code(x, y, z, t) return Float64(x - Float64(log1p(Float64(y * expm1(z))) / t)) end
code[x_, y_, z_, t_] := N[(x - N[(N[Log[1 + N[(y * N[(Exp[z] - 1), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] / t), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
x - \frac{\mathsf{log1p}\left(y \cdot \mathsf{expm1}\left(z\right)\right)}{t}
\end{array}
Initial program 60.3%
associate-+l-75.9%
sub-neg75.9%
log1p-def81.8%
neg-sub081.8%
associate-+l-81.8%
neg-sub081.8%
neg-mul-181.8%
*-commutative81.8%
distribute-rgt-out81.8%
+-commutative81.8%
metadata-eval81.8%
sub-neg81.8%
expm1-def97.3%
Simplified97.3%
Final simplification97.3%
(FPCore (x y z t) :precision binary64 (if (<= x -1.3e+24) x (- x (* y (/ (expm1 z) t)))))
double code(double x, double y, double z, double t) {
double tmp;
if (x <= -1.3e+24) {
tmp = x;
} else {
tmp = x - (y * (expm1(z) / t));
}
return tmp;
}
public static double code(double x, double y, double z, double t) {
double tmp;
if (x <= -1.3e+24) {
tmp = x;
} else {
tmp = x - (y * (Math.expm1(z) / t));
}
return tmp;
}
def code(x, y, z, t): tmp = 0 if x <= -1.3e+24: tmp = x else: tmp = x - (y * (math.expm1(z) / t)) return tmp
function code(x, y, z, t) tmp = 0.0 if (x <= -1.3e+24) tmp = x; else tmp = Float64(x - Float64(y * Float64(expm1(z) / t))); end return tmp end
code[x_, y_, z_, t_] := If[LessEqual[x, -1.3e+24], x, N[(x - N[(y * N[(N[(Exp[z] - 1), $MachinePrecision] / t), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;x \leq -1.3 \cdot 10^{+24}:\\
\;\;\;\;x\\
\mathbf{else}:\\
\;\;\;\;x - y \cdot \frac{\mathsf{expm1}\left(z\right)}{t}\\
\end{array}
\end{array}
if x < -1.2999999999999999e24Initial program 79.1%
associate-+l-95.7%
sub-neg95.7%
log1p-def97.9%
neg-sub097.9%
associate-+l-97.9%
neg-sub097.9%
neg-mul-197.9%
*-commutative97.9%
distribute-rgt-out97.9%
+-commutative97.9%
metadata-eval97.9%
sub-neg97.9%
expm1-def99.9%
Simplified99.9%
Taylor expanded in z around 0 72.9%
associate-/l*72.9%
associate-/r/71.2%
Simplified71.2%
associate-*l/72.9%
associate-/l*72.9%
Applied egg-rr72.9%
Taylor expanded in x around inf 89.9%
if -1.2999999999999999e24 < x Initial program 54.9%
associate-+l-70.3%
sub-neg70.3%
log1p-def77.2%
neg-sub077.2%
associate-+l-77.2%
neg-sub077.2%
neg-mul-177.2%
*-commutative77.2%
distribute-rgt-out77.2%
+-commutative77.2%
metadata-eval77.2%
sub-neg77.2%
expm1-def96.5%
Simplified96.5%
Taylor expanded in y around 0 72.1%
associate-/l*71.6%
associate-/r/72.1%
expm1-def90.5%
Simplified90.5%
Final simplification90.4%
(FPCore (x y z t) :precision binary64 (if (<= z -3.6e-11) x (- x (* z (/ y t)))))
double code(double x, double y, double z, double t) {
double tmp;
if (z <= -3.6e-11) {
tmp = x;
} else {
tmp = x - (z * (y / t));
}
return tmp;
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
real(8) :: tmp
if (z <= (-3.6d-11)) then
tmp = x
else
tmp = x - (z * (y / t))
end if
code = tmp
end function
public static double code(double x, double y, double z, double t) {
double tmp;
if (z <= -3.6e-11) {
tmp = x;
} else {
tmp = x - (z * (y / t));
}
return tmp;
}
def code(x, y, z, t): tmp = 0 if z <= -3.6e-11: tmp = x else: tmp = x - (z * (y / t)) return tmp
function code(x, y, z, t) tmp = 0.0 if (z <= -3.6e-11) tmp = x; else tmp = Float64(x - Float64(z * Float64(y / t))); end return tmp end
function tmp_2 = code(x, y, z, t) tmp = 0.0; if (z <= -3.6e-11) tmp = x; else tmp = x - (z * (y / t)); end tmp_2 = tmp; end
code[x_, y_, z_, t_] := If[LessEqual[z, -3.6e-11], x, N[(x - N[(z * N[(y / t), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;z \leq -3.6 \cdot 10^{-11}:\\
\;\;\;\;x\\
\mathbf{else}:\\
\;\;\;\;x - z \cdot \frac{y}{t}\\
\end{array}
\end{array}
if z < -3.59999999999999985e-11Initial program 81.3%
associate-+l-81.3%
sub-neg81.3%
log1p-def99.8%
neg-sub099.8%
associate-+l-99.8%
neg-sub099.8%
neg-mul-199.8%
*-commutative99.8%
distribute-rgt-out99.8%
+-commutative99.8%
metadata-eval99.8%
sub-neg99.8%
expm1-def99.9%
Simplified99.9%
Taylor expanded in z around 0 43.4%
associate-/l*40.8%
associate-/r/43.5%
Simplified43.5%
associate-*l/43.4%
associate-/l*40.8%
Applied egg-rr40.8%
Taylor expanded in x around inf 65.9%
if -3.59999999999999985e-11 < z Initial program 50.7%
associate-+l-73.5%
sub-neg73.5%
log1p-def73.6%
neg-sub073.6%
associate-+l-73.6%
neg-sub073.6%
neg-mul-173.6%
*-commutative73.6%
distribute-rgt-out73.7%
+-commutative73.7%
metadata-eval73.7%
sub-neg73.7%
expm1-def96.1%
Simplified96.1%
Taylor expanded in z around 0 90.0%
associate-/l*94.1%
associate-/r/89.9%
Simplified89.9%
Final simplification82.4%
(FPCore (x y z t) :precision binary64 (if (<= z -4.4e-11) x (- x (/ y (/ t z)))))
double code(double x, double y, double z, double t) {
double tmp;
if (z <= -4.4e-11) {
tmp = x;
} else {
tmp = x - (y / (t / z));
}
return tmp;
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
real(8) :: tmp
if (z <= (-4.4d-11)) then
tmp = x
else
tmp = x - (y / (t / z))
end if
code = tmp
end function
public static double code(double x, double y, double z, double t) {
double tmp;
if (z <= -4.4e-11) {
tmp = x;
} else {
tmp = x - (y / (t / z));
}
return tmp;
}
def code(x, y, z, t): tmp = 0 if z <= -4.4e-11: tmp = x else: tmp = x - (y / (t / z)) return tmp
function code(x, y, z, t) tmp = 0.0 if (z <= -4.4e-11) tmp = x; else tmp = Float64(x - Float64(y / Float64(t / z))); end return tmp end
function tmp_2 = code(x, y, z, t) tmp = 0.0; if (z <= -4.4e-11) tmp = x; else tmp = x - (y / (t / z)); end tmp_2 = tmp; end
code[x_, y_, z_, t_] := If[LessEqual[z, -4.4e-11], x, N[(x - N[(y / N[(t / z), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;z \leq -4.4 \cdot 10^{-11}:\\
\;\;\;\;x\\
\mathbf{else}:\\
\;\;\;\;x - \frac{y}{\frac{t}{z}}\\
\end{array}
\end{array}
if z < -4.4000000000000003e-11Initial program 81.3%
associate-+l-81.3%
sub-neg81.3%
log1p-def99.8%
neg-sub099.8%
associate-+l-99.8%
neg-sub099.8%
neg-mul-199.8%
*-commutative99.8%
distribute-rgt-out99.8%
+-commutative99.8%
metadata-eval99.8%
sub-neg99.8%
expm1-def99.9%
Simplified99.9%
Taylor expanded in z around 0 43.4%
associate-/l*40.8%
associate-/r/43.5%
Simplified43.5%
associate-*l/43.4%
associate-/l*40.8%
Applied egg-rr40.8%
Taylor expanded in x around inf 65.9%
if -4.4000000000000003e-11 < z Initial program 50.7%
associate-+l-73.5%
sub-neg73.5%
log1p-def73.6%
neg-sub073.6%
associate-+l-73.6%
neg-sub073.6%
neg-mul-173.6%
*-commutative73.6%
distribute-rgt-out73.7%
+-commutative73.7%
metadata-eval73.7%
sub-neg73.7%
expm1-def96.1%
Simplified96.1%
Taylor expanded in z around 0 90.0%
associate-/l*94.1%
associate-/r/89.9%
Simplified89.9%
associate-*l/90.0%
associate-/l*94.1%
Applied egg-rr94.1%
Final simplification85.3%
(FPCore (x y z t) :precision binary64 x)
double code(double x, double y, double z, double t) {
return x;
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
code = x
end function
public static double code(double x, double y, double z, double t) {
return x;
}
def code(x, y, z, t): return x
function code(x, y, z, t) return x end
function tmp = code(x, y, z, t) tmp = x; end
code[x_, y_, z_, t_] := x
\begin{array}{l}
\\
x
\end{array}
Initial program 60.3%
associate-+l-75.9%
sub-neg75.9%
log1p-def81.8%
neg-sub081.8%
associate-+l-81.8%
neg-sub081.8%
neg-mul-181.8%
*-commutative81.8%
distribute-rgt-out81.8%
+-commutative81.8%
metadata-eval81.8%
sub-neg81.8%
expm1-def97.3%
Simplified97.3%
Taylor expanded in z around 0 75.5%
associate-/l*77.4%
associate-/r/75.4%
Simplified75.4%
associate-*l/75.5%
associate-/l*77.4%
Applied egg-rr77.4%
Taylor expanded in x around inf 70.6%
Final simplification70.6%
(FPCore (x y z t)
:precision binary64
(let* ((t_1 (/ (- 0.5) (* y t))))
(if (< z -2.8874623088207947e+119)
(- (- x (/ t_1 (* z z))) (* t_1 (/ (/ 2.0 z) (* z z))))
(- x (/ (log (+ 1.0 (* z y))) t)))))
double code(double x, double y, double z, double t) {
double t_1 = -0.5 / (y * t);
double tmp;
if (z < -2.8874623088207947e+119) {
tmp = (x - (t_1 / (z * z))) - (t_1 * ((2.0 / z) / (z * z)));
} else {
tmp = x - (log((1.0 + (z * y))) / t);
}
return tmp;
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
real(8) :: t_1
real(8) :: tmp
t_1 = -0.5d0 / (y * t)
if (z < (-2.8874623088207947d+119)) then
tmp = (x - (t_1 / (z * z))) - (t_1 * ((2.0d0 / z) / (z * z)))
else
tmp = x - (log((1.0d0 + (z * y))) / t)
end if
code = tmp
end function
public static double code(double x, double y, double z, double t) {
double t_1 = -0.5 / (y * t);
double tmp;
if (z < -2.8874623088207947e+119) {
tmp = (x - (t_1 / (z * z))) - (t_1 * ((2.0 / z) / (z * z)));
} else {
tmp = x - (Math.log((1.0 + (z * y))) / t);
}
return tmp;
}
def code(x, y, z, t): t_1 = -0.5 / (y * t) tmp = 0 if z < -2.8874623088207947e+119: tmp = (x - (t_1 / (z * z))) - (t_1 * ((2.0 / z) / (z * z))) else: tmp = x - (math.log((1.0 + (z * y))) / t) return tmp
function code(x, y, z, t) t_1 = Float64(Float64(-0.5) / Float64(y * t)) tmp = 0.0 if (z < -2.8874623088207947e+119) tmp = Float64(Float64(x - Float64(t_1 / Float64(z * z))) - Float64(t_1 * Float64(Float64(2.0 / z) / Float64(z * z)))); else tmp = Float64(x - Float64(log(Float64(1.0 + Float64(z * y))) / t)); end return tmp end
function tmp_2 = code(x, y, z, t) t_1 = -0.5 / (y * t); tmp = 0.0; if (z < -2.8874623088207947e+119) tmp = (x - (t_1 / (z * z))) - (t_1 * ((2.0 / z) / (z * z))); else tmp = x - (log((1.0 + (z * y))) / t); end tmp_2 = tmp; end
code[x_, y_, z_, t_] := Block[{t$95$1 = N[((-0.5) / N[(y * t), $MachinePrecision]), $MachinePrecision]}, If[Less[z, -2.8874623088207947e+119], N[(N[(x - N[(t$95$1 / N[(z * z), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] - N[(t$95$1 * N[(N[(2.0 / z), $MachinePrecision] / N[(z * z), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(x - N[(N[Log[N[(1.0 + N[(z * y), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] / t), $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}
\\
\begin{array}{l}
t_1 := \frac{-0.5}{y \cdot t}\\
\mathbf{if}\;z < -2.8874623088207947 \cdot 10^{+119}:\\
\;\;\;\;\left(x - \frac{t_1}{z \cdot z}\right) - t_1 \cdot \frac{\frac{2}{z}}{z \cdot z}\\
\mathbf{else}:\\
\;\;\;\;x - \frac{\log \left(1 + z \cdot y\right)}{t}\\
\end{array}
\end{array}
herbie shell --seed 2023173
(FPCore (x y z t)
:name "System.Random.MWC.Distributions:truncatedExp from mwc-random-0.13.3.2"
:precision binary64
:herbie-target
(if (< z -2.8874623088207947e+119) (- (- x (/ (/ (- 0.5) (* y t)) (* z z))) (* (/ (- 0.5) (* y t)) (/ (/ 2.0 z) (* z z)))) (- x (/ (log (+ 1.0 (* z y))) t)))
(- x (/ (log (+ (- 1.0 y) (* y (exp z)))) t)))