
(FPCore (x y) :precision binary64 (/ (exp (* x (log (/ x (+ x y))))) x))
double code(double x, double y) {
return exp((x * log((x / (x + y))))) / x;
}
real(8) function code(x, y)
real(8), intent (in) :: x
real(8), intent (in) :: y
code = exp((x * log((x / (x + y))))) / x
end function
public static double code(double x, double y) {
return Math.exp((x * Math.log((x / (x + y))))) / x;
}
def code(x, y): return math.exp((x * math.log((x / (x + y))))) / x
function code(x, y) return Float64(exp(Float64(x * log(Float64(x / Float64(x + y))))) / x) end
function tmp = code(x, y) tmp = exp((x * log((x / (x + y))))) / x; end
code[x_, y_] := N[(N[Exp[N[(x * N[Log[N[(x / N[(x + y), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]], $MachinePrecision] / x), $MachinePrecision]
\begin{array}{l}
\\
\frac{e^{x \cdot \log \left(\frac{x}{x + y}\right)}}{x}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 6 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (x y) :precision binary64 (/ (exp (* x (log (/ x (+ x y))))) x))
double code(double x, double y) {
return exp((x * log((x / (x + y))))) / x;
}
real(8) function code(x, y)
real(8), intent (in) :: x
real(8), intent (in) :: y
code = exp((x * log((x / (x + y))))) / x
end function
public static double code(double x, double y) {
return Math.exp((x * Math.log((x / (x + y))))) / x;
}
def code(x, y): return math.exp((x * math.log((x / (x + y))))) / x
function code(x, y) return Float64(exp(Float64(x * log(Float64(x / Float64(x + y))))) / x) end
function tmp = code(x, y) tmp = exp((x * log((x / (x + y))))) / x; end
code[x_, y_] := N[(N[Exp[N[(x * N[Log[N[(x / N[(x + y), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]], $MachinePrecision] / x), $MachinePrecision]
\begin{array}{l}
\\
\frac{e^{x \cdot \log \left(\frac{x}{x + y}\right)}}{x}
\end{array}
(FPCore (x y) :precision binary64 (if (<= x -20000000000000.0) (pow (* x (exp y)) -1.0) (if (<= x 5.0) (/ (pow (exp x) (log (/ x (+ x y)))) x) (/ (exp (- y)) x))))
double code(double x, double y) {
double tmp;
if (x <= -20000000000000.0) {
tmp = pow((x * exp(y)), -1.0);
} else if (x <= 5.0) {
tmp = pow(exp(x), log((x / (x + y)))) / x;
} else {
tmp = exp(-y) / x;
}
return tmp;
}
real(8) function code(x, y)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8) :: tmp
if (x <= (-20000000000000.0d0)) then
tmp = (x * exp(y)) ** (-1.0d0)
else if (x <= 5.0d0) then
tmp = (exp(x) ** log((x / (x + y)))) / x
else
tmp = exp(-y) / x
end if
code = tmp
end function
public static double code(double x, double y) {
double tmp;
if (x <= -20000000000000.0) {
tmp = Math.pow((x * Math.exp(y)), -1.0);
} else if (x <= 5.0) {
tmp = Math.pow(Math.exp(x), Math.log((x / (x + y)))) / x;
} else {
tmp = Math.exp(-y) / x;
}
return tmp;
}
def code(x, y): tmp = 0 if x <= -20000000000000.0: tmp = math.pow((x * math.exp(y)), -1.0) elif x <= 5.0: tmp = math.pow(math.exp(x), math.log((x / (x + y)))) / x else: tmp = math.exp(-y) / x return tmp
function code(x, y) tmp = 0.0 if (x <= -20000000000000.0) tmp = Float64(x * exp(y)) ^ -1.0; elseif (x <= 5.0) tmp = Float64((exp(x) ^ log(Float64(x / Float64(x + y)))) / x); else tmp = Float64(exp(Float64(-y)) / x); end return tmp end
function tmp_2 = code(x, y) tmp = 0.0; if (x <= -20000000000000.0) tmp = (x * exp(y)) ^ -1.0; elseif (x <= 5.0) tmp = (exp(x) ^ log((x / (x + y)))) / x; else tmp = exp(-y) / x; end tmp_2 = tmp; end
code[x_, y_] := If[LessEqual[x, -20000000000000.0], N[Power[N[(x * N[Exp[y], $MachinePrecision]), $MachinePrecision], -1.0], $MachinePrecision], If[LessEqual[x, 5.0], N[(N[Power[N[Exp[x], $MachinePrecision], N[Log[N[(x / N[(x + y), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]], $MachinePrecision] / x), $MachinePrecision], N[(N[Exp[(-y)], $MachinePrecision] / x), $MachinePrecision]]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;x \leq -20000000000000:\\
\;\;\;\;{\left(x \cdot e^{y}\right)}^{-1}\\
\mathbf{elif}\;x \leq 5:\\
\;\;\;\;\frac{{\left(e^{x}\right)}^{\log \left(\frac{x}{x + y}\right)}}{x}\\
\mathbf{else}:\\
\;\;\;\;\frac{e^{-y}}{x}\\
\end{array}
\end{array}
if x < -2e13Initial program 79.8%
*-commutative79.8%
exp-to-pow79.8%
Simplified79.8%
Taylor expanded in x around inf 100.0%
mul-1-neg100.0%
Simplified100.0%
clear-num100.0%
inv-pow100.0%
div-inv100.0%
add-sqr-sqrt68.4%
sqrt-unprod90.7%
sqr-neg90.7%
sqrt-prod22.3%
add-sqr-sqrt63.7%
exp-neg63.7%
add-sqr-sqrt41.4%
sqrt-unprod73.0%
sqr-neg73.0%
sqrt-prod31.6%
add-sqr-sqrt100.0%
Applied egg-rr100.0%
if -2e13 < x < 5Initial program 78.6%
exp-prod99.6%
Simplified99.6%
if 5 < x Initial program 86.3%
*-commutative86.3%
exp-to-pow86.3%
Simplified86.3%
Taylor expanded in x around inf 100.0%
mul-1-neg100.0%
Simplified100.0%
Final simplification99.8%
(FPCore (x y) :precision binary64 (if (<= x -0.45) (pow (* x (exp y)) -1.0) (if (<= x 0.76) (/ 1.0 x) (/ (exp (- y)) x))))
double code(double x, double y) {
double tmp;
if (x <= -0.45) {
tmp = pow((x * exp(y)), -1.0);
} else if (x <= 0.76) {
tmp = 1.0 / x;
} else {
tmp = exp(-y) / x;
}
return tmp;
}
real(8) function code(x, y)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8) :: tmp
if (x <= (-0.45d0)) then
tmp = (x * exp(y)) ** (-1.0d0)
else if (x <= 0.76d0) then
tmp = 1.0d0 / x
else
tmp = exp(-y) / x
end if
code = tmp
end function
public static double code(double x, double y) {
double tmp;
if (x <= -0.45) {
tmp = Math.pow((x * Math.exp(y)), -1.0);
} else if (x <= 0.76) {
tmp = 1.0 / x;
} else {
tmp = Math.exp(-y) / x;
}
return tmp;
}
def code(x, y): tmp = 0 if x <= -0.45: tmp = math.pow((x * math.exp(y)), -1.0) elif x <= 0.76: tmp = 1.0 / x else: tmp = math.exp(-y) / x return tmp
function code(x, y) tmp = 0.0 if (x <= -0.45) tmp = Float64(x * exp(y)) ^ -1.0; elseif (x <= 0.76) tmp = Float64(1.0 / x); else tmp = Float64(exp(Float64(-y)) / x); end return tmp end
function tmp_2 = code(x, y) tmp = 0.0; if (x <= -0.45) tmp = (x * exp(y)) ^ -1.0; elseif (x <= 0.76) tmp = 1.0 / x; else tmp = exp(-y) / x; end tmp_2 = tmp; end
code[x_, y_] := If[LessEqual[x, -0.45], N[Power[N[(x * N[Exp[y], $MachinePrecision]), $MachinePrecision], -1.0], $MachinePrecision], If[LessEqual[x, 0.76], N[(1.0 / x), $MachinePrecision], N[(N[Exp[(-y)], $MachinePrecision] / x), $MachinePrecision]]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;x \leq -0.45:\\
\;\;\;\;{\left(x \cdot e^{y}\right)}^{-1}\\
\mathbf{elif}\;x \leq 0.76:\\
\;\;\;\;\frac{1}{x}\\
\mathbf{else}:\\
\;\;\;\;\frac{e^{-y}}{x}\\
\end{array}
\end{array}
if x < -0.450000000000000011Initial program 80.8%
*-commutative80.8%
exp-to-pow80.8%
Simplified80.8%
Taylor expanded in x around inf 100.0%
mul-1-neg100.0%
Simplified100.0%
clear-num100.0%
inv-pow100.0%
div-inv100.0%
add-sqr-sqrt68.8%
sqrt-unprod91.2%
sqr-neg91.2%
sqrt-prod22.5%
add-sqr-sqrt63.1%
exp-neg63.1%
add-sqr-sqrt40.6%
sqrt-unprod71.9%
sqr-neg71.9%
sqrt-prod31.2%
add-sqr-sqrt100.0%
Applied egg-rr100.0%
if -0.450000000000000011 < x < 0.76000000000000001Initial program 77.8%
exp-prod99.6%
Simplified99.6%
Taylor expanded in x around 0 97.6%
if 0.76000000000000001 < x Initial program 86.3%
*-commutative86.3%
exp-to-pow86.3%
Simplified86.3%
Taylor expanded in x around inf 100.0%
mul-1-neg100.0%
Simplified100.0%
Final simplification99.0%
(FPCore (x y) :precision binary64 (if (or (<= x -0.195) (not (<= x 1.0))) (/ (exp (- y)) x) (/ 1.0 x)))
double code(double x, double y) {
double tmp;
if ((x <= -0.195) || !(x <= 1.0)) {
tmp = exp(-y) / x;
} else {
tmp = 1.0 / x;
}
return tmp;
}
real(8) function code(x, y)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8) :: tmp
if ((x <= (-0.195d0)) .or. (.not. (x <= 1.0d0))) then
tmp = exp(-y) / x
else
tmp = 1.0d0 / x
end if
code = tmp
end function
public static double code(double x, double y) {
double tmp;
if ((x <= -0.195) || !(x <= 1.0)) {
tmp = Math.exp(-y) / x;
} else {
tmp = 1.0 / x;
}
return tmp;
}
def code(x, y): tmp = 0 if (x <= -0.195) or not (x <= 1.0): tmp = math.exp(-y) / x else: tmp = 1.0 / x return tmp
function code(x, y) tmp = 0.0 if ((x <= -0.195) || !(x <= 1.0)) tmp = Float64(exp(Float64(-y)) / x); else tmp = Float64(1.0 / x); end return tmp end
function tmp_2 = code(x, y) tmp = 0.0; if ((x <= -0.195) || ~((x <= 1.0))) tmp = exp(-y) / x; else tmp = 1.0 / x; end tmp_2 = tmp; end
code[x_, y_] := If[Or[LessEqual[x, -0.195], N[Not[LessEqual[x, 1.0]], $MachinePrecision]], N[(N[Exp[(-y)], $MachinePrecision] / x), $MachinePrecision], N[(1.0 / x), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;x \leq -0.195 \lor \neg \left(x \leq 1\right):\\
\;\;\;\;\frac{e^{-y}}{x}\\
\mathbf{else}:\\
\;\;\;\;\frac{1}{x}\\
\end{array}
\end{array}
if x < -0.19500000000000001 or 1 < x Initial program 83.3%
*-commutative83.3%
exp-to-pow83.3%
Simplified83.3%
Taylor expanded in x around inf 100.0%
mul-1-neg100.0%
Simplified100.0%
if -0.19500000000000001 < x < 1Initial program 77.8%
exp-prod99.6%
Simplified99.6%
Taylor expanded in x around 0 97.6%
Final simplification99.0%
(FPCore (x y) :precision binary64 (if (<= x -0.39) (+ (- (/ 1.0 x) (/ y x)) (/ (* y y) (* x 2.0))) (/ 1.0 x)))
double code(double x, double y) {
double tmp;
if (x <= -0.39) {
tmp = ((1.0 / x) - (y / x)) + ((y * y) / (x * 2.0));
} else {
tmp = 1.0 / x;
}
return tmp;
}
real(8) function code(x, y)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8) :: tmp
if (x <= (-0.39d0)) then
tmp = ((1.0d0 / x) - (y / x)) + ((y * y) / (x * 2.0d0))
else
tmp = 1.0d0 / x
end if
code = tmp
end function
public static double code(double x, double y) {
double tmp;
if (x <= -0.39) {
tmp = ((1.0 / x) - (y / x)) + ((y * y) / (x * 2.0));
} else {
tmp = 1.0 / x;
}
return tmp;
}
def code(x, y): tmp = 0 if x <= -0.39: tmp = ((1.0 / x) - (y / x)) + ((y * y) / (x * 2.0)) else: tmp = 1.0 / x return tmp
function code(x, y) tmp = 0.0 if (x <= -0.39) tmp = Float64(Float64(Float64(1.0 / x) - Float64(y / x)) + Float64(Float64(y * y) / Float64(x * 2.0))); else tmp = Float64(1.0 / x); end return tmp end
function tmp_2 = code(x, y) tmp = 0.0; if (x <= -0.39) tmp = ((1.0 / x) - (y / x)) + ((y * y) / (x * 2.0)); else tmp = 1.0 / x; end tmp_2 = tmp; end
code[x_, y_] := If[LessEqual[x, -0.39], N[(N[(N[(1.0 / x), $MachinePrecision] - N[(y / x), $MachinePrecision]), $MachinePrecision] + N[(N[(y * y), $MachinePrecision] / N[(x * 2.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(1.0 / x), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;x \leq -0.39:\\
\;\;\;\;\left(\frac{1}{x} - \frac{y}{x}\right) + \frac{y \cdot y}{x \cdot 2}\\
\mathbf{else}:\\
\;\;\;\;\frac{1}{x}\\
\end{array}
\end{array}
if x < -0.39000000000000001Initial program 80.8%
exp-prod80.8%
Simplified80.8%
Taylor expanded in x around inf 65.4%
associate-+r+65.4%
+-commutative65.4%
associate-*r/65.4%
distribute-rgt-out65.4%
metadata-eval65.4%
*-rgt-identity65.4%
associate-*l/65.4%
metadata-eval65.4%
associate-*r/65.4%
distribute-rgt-in80.4%
mul-1-neg80.4%
unsub-neg80.4%
unpow280.4%
associate-*r/80.4%
metadata-eval80.4%
Simplified80.4%
Taylor expanded in y around inf 80.5%
associate-+r+80.5%
+-commutative80.5%
neg-mul-180.5%
sub-neg80.5%
unpow280.5%
associate-/l*80.5%
associate-*r/80.5%
metadata-eval80.5%
Simplified80.5%
Taylor expanded in x around inf 80.5%
*-commutative80.5%
Simplified80.5%
if -0.39000000000000001 < x Initial program 81.1%
exp-prod94.5%
Simplified94.5%
Taylor expanded in x around 0 84.0%
Final simplification82.9%
(FPCore (x y) :precision binary64 (if (<= x -0.47) (/ (+ (- 1.0 y) (* y (* y 0.5))) x) (/ 1.0 x)))
double code(double x, double y) {
double tmp;
if (x <= -0.47) {
tmp = ((1.0 - y) + (y * (y * 0.5))) / x;
} else {
tmp = 1.0 / x;
}
return tmp;
}
real(8) function code(x, y)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8) :: tmp
if (x <= (-0.47d0)) then
tmp = ((1.0d0 - y) + (y * (y * 0.5d0))) / x
else
tmp = 1.0d0 / x
end if
code = tmp
end function
public static double code(double x, double y) {
double tmp;
if (x <= -0.47) {
tmp = ((1.0 - y) + (y * (y * 0.5))) / x;
} else {
tmp = 1.0 / x;
}
return tmp;
}
def code(x, y): tmp = 0 if x <= -0.47: tmp = ((1.0 - y) + (y * (y * 0.5))) / x else: tmp = 1.0 / x return tmp
function code(x, y) tmp = 0.0 if (x <= -0.47) tmp = Float64(Float64(Float64(1.0 - y) + Float64(y * Float64(y * 0.5))) / x); else tmp = Float64(1.0 / x); end return tmp end
function tmp_2 = code(x, y) tmp = 0.0; if (x <= -0.47) tmp = ((1.0 - y) + (y * (y * 0.5))) / x; else tmp = 1.0 / x; end tmp_2 = tmp; end
code[x_, y_] := If[LessEqual[x, -0.47], N[(N[(N[(1.0 - y), $MachinePrecision] + N[(y * N[(y * 0.5), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / x), $MachinePrecision], N[(1.0 / x), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;x \leq -0.47:\\
\;\;\;\;\frac{\left(1 - y\right) + y \cdot \left(y \cdot 0.5\right)}{x}\\
\mathbf{else}:\\
\;\;\;\;\frac{1}{x}\\
\end{array}
\end{array}
if x < -0.46999999999999997Initial program 80.8%
exp-prod80.8%
Simplified80.8%
Taylor expanded in x around inf 65.4%
associate-+r+65.4%
+-commutative65.4%
associate-*r/65.4%
distribute-rgt-out65.4%
metadata-eval65.4%
*-rgt-identity65.4%
associate-*l/65.4%
metadata-eval65.4%
associate-*r/65.4%
distribute-rgt-in80.4%
mul-1-neg80.4%
unsub-neg80.4%
unpow280.4%
associate-*r/80.4%
metadata-eval80.4%
Simplified80.4%
Taylor expanded in x around inf 80.4%
unpow280.4%
*-commutative80.4%
associate-*r*80.4%
Simplified80.4%
if -0.46999999999999997 < x Initial program 81.1%
exp-prod94.5%
Simplified94.5%
Taylor expanded in x around 0 84.0%
Final simplification82.9%
(FPCore (x y) :precision binary64 (/ 1.0 x))
double code(double x, double y) {
return 1.0 / x;
}
real(8) function code(x, y)
real(8), intent (in) :: x
real(8), intent (in) :: y
code = 1.0d0 / x
end function
public static double code(double x, double y) {
return 1.0 / x;
}
def code(x, y): return 1.0 / x
function code(x, y) return Float64(1.0 / x) end
function tmp = code(x, y) tmp = 1.0 / x; end
code[x_, y_] := N[(1.0 / x), $MachinePrecision]
\begin{array}{l}
\\
\frac{1}{x}
\end{array}
Initial program 81.0%
exp-prod90.2%
Simplified90.2%
Taylor expanded in x around 0 77.6%
Final simplification77.6%
(FPCore (x y)
:precision binary64
(let* ((t_0 (/ (exp (/ -1.0 y)) x)) (t_1 (/ (pow (/ x (+ y x)) x) x)))
(if (< y -3.7311844206647956e+94)
t_0
(if (< y 2.817959242728288e+37)
t_1
(if (< y 2.347387415166998e+178) (log (exp t_1)) t_0)))))
double code(double x, double y) {
double t_0 = exp((-1.0 / y)) / x;
double t_1 = pow((x / (y + x)), x) / x;
double tmp;
if (y < -3.7311844206647956e+94) {
tmp = t_0;
} else if (y < 2.817959242728288e+37) {
tmp = t_1;
} else if (y < 2.347387415166998e+178) {
tmp = log(exp(t_1));
} else {
tmp = t_0;
}
return tmp;
}
real(8) function code(x, y)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8) :: t_0
real(8) :: t_1
real(8) :: tmp
t_0 = exp(((-1.0d0) / y)) / x
t_1 = ((x / (y + x)) ** x) / x
if (y < (-3.7311844206647956d+94)) then
tmp = t_0
else if (y < 2.817959242728288d+37) then
tmp = t_1
else if (y < 2.347387415166998d+178) then
tmp = log(exp(t_1))
else
tmp = t_0
end if
code = tmp
end function
public static double code(double x, double y) {
double t_0 = Math.exp((-1.0 / y)) / x;
double t_1 = Math.pow((x / (y + x)), x) / x;
double tmp;
if (y < -3.7311844206647956e+94) {
tmp = t_0;
} else if (y < 2.817959242728288e+37) {
tmp = t_1;
} else if (y < 2.347387415166998e+178) {
tmp = Math.log(Math.exp(t_1));
} else {
tmp = t_0;
}
return tmp;
}
def code(x, y): t_0 = math.exp((-1.0 / y)) / x t_1 = math.pow((x / (y + x)), x) / x tmp = 0 if y < -3.7311844206647956e+94: tmp = t_0 elif y < 2.817959242728288e+37: tmp = t_1 elif y < 2.347387415166998e+178: tmp = math.log(math.exp(t_1)) else: tmp = t_0 return tmp
function code(x, y) t_0 = Float64(exp(Float64(-1.0 / y)) / x) t_1 = Float64((Float64(x / Float64(y + x)) ^ x) / x) tmp = 0.0 if (y < -3.7311844206647956e+94) tmp = t_0; elseif (y < 2.817959242728288e+37) tmp = t_1; elseif (y < 2.347387415166998e+178) tmp = log(exp(t_1)); else tmp = t_0; end return tmp end
function tmp_2 = code(x, y) t_0 = exp((-1.0 / y)) / x; t_1 = ((x / (y + x)) ^ x) / x; tmp = 0.0; if (y < -3.7311844206647956e+94) tmp = t_0; elseif (y < 2.817959242728288e+37) tmp = t_1; elseif (y < 2.347387415166998e+178) tmp = log(exp(t_1)); else tmp = t_0; end tmp_2 = tmp; end
code[x_, y_] := Block[{t$95$0 = N[(N[Exp[N[(-1.0 / y), $MachinePrecision]], $MachinePrecision] / x), $MachinePrecision]}, Block[{t$95$1 = N[(N[Power[N[(x / N[(y + x), $MachinePrecision]), $MachinePrecision], x], $MachinePrecision] / x), $MachinePrecision]}, If[Less[y, -3.7311844206647956e+94], t$95$0, If[Less[y, 2.817959242728288e+37], t$95$1, If[Less[y, 2.347387415166998e+178], N[Log[N[Exp[t$95$1], $MachinePrecision]], $MachinePrecision], t$95$0]]]]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \frac{e^{\frac{-1}{y}}}{x}\\
t_1 := \frac{{\left(\frac{x}{y + x}\right)}^{x}}{x}\\
\mathbf{if}\;y < -3.7311844206647956 \cdot 10^{+94}:\\
\;\;\;\;t_0\\
\mathbf{elif}\;y < 2.817959242728288 \cdot 10^{+37}:\\
\;\;\;\;t_1\\
\mathbf{elif}\;y < 2.347387415166998 \cdot 10^{+178}:\\
\;\;\;\;\log \left(e^{t_1}\right)\\
\mathbf{else}:\\
\;\;\;\;t_0\\
\end{array}
\end{array}
herbie shell --seed 2023290
(FPCore (x y)
:name "Numeric.SpecFunctions:invIncompleteBetaWorker from math-functions-0.1.5.2, F"
:precision binary64
:herbie-target
(if (< y -3.7311844206647956e+94) (/ (exp (/ -1.0 y)) x) (if (< y 2.817959242728288e+37) (/ (pow (/ x (+ y x)) x) x) (if (< y 2.347387415166998e+178) (log (exp (/ (pow (/ x (+ y x)) x) x))) (/ (exp (/ -1.0 y)) x))))
(/ (exp (* x (log (/ x (+ x y))))) x))