
(FPCore (a b eps) :precision binary64 (/ (* eps (- (exp (* (+ a b) eps)) 1.0)) (* (- (exp (* a eps)) 1.0) (- (exp (* b eps)) 1.0))))
double code(double a, double b, double eps) {
return (eps * (exp(((a + b) * eps)) - 1.0)) / ((exp((a * eps)) - 1.0) * (exp((b * eps)) - 1.0));
}
real(8) function code(a, b, eps)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: eps
code = (eps * (exp(((a + b) * eps)) - 1.0d0)) / ((exp((a * eps)) - 1.0d0) * (exp((b * eps)) - 1.0d0))
end function
public static double code(double a, double b, double eps) {
return (eps * (Math.exp(((a + b) * eps)) - 1.0)) / ((Math.exp((a * eps)) - 1.0) * (Math.exp((b * eps)) - 1.0));
}
def code(a, b, eps): return (eps * (math.exp(((a + b) * eps)) - 1.0)) / ((math.exp((a * eps)) - 1.0) * (math.exp((b * eps)) - 1.0))
function code(a, b, eps) return Float64(Float64(eps * Float64(exp(Float64(Float64(a + b) * eps)) - 1.0)) / Float64(Float64(exp(Float64(a * eps)) - 1.0) * Float64(exp(Float64(b * eps)) - 1.0))) end
function tmp = code(a, b, eps) tmp = (eps * (exp(((a + b) * eps)) - 1.0)) / ((exp((a * eps)) - 1.0) * (exp((b * eps)) - 1.0)); end
code[a_, b_, eps_] := N[(N[(eps * N[(N[Exp[N[(N[(a + b), $MachinePrecision] * eps), $MachinePrecision]], $MachinePrecision] - 1.0), $MachinePrecision]), $MachinePrecision] / N[(N[(N[Exp[N[(a * eps), $MachinePrecision]], $MachinePrecision] - 1.0), $MachinePrecision] * N[(N[Exp[N[(b * eps), $MachinePrecision]], $MachinePrecision] - 1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 3 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (a b eps) :precision binary64 (/ (* eps (- (exp (* (+ a b) eps)) 1.0)) (* (- (exp (* a eps)) 1.0) (- (exp (* b eps)) 1.0))))
double code(double a, double b, double eps) {
return (eps * (exp(((a + b) * eps)) - 1.0)) / ((exp((a * eps)) - 1.0) * (exp((b * eps)) - 1.0));
}
real(8) function code(a, b, eps)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: eps
code = (eps * (exp(((a + b) * eps)) - 1.0d0)) / ((exp((a * eps)) - 1.0d0) * (exp((b * eps)) - 1.0d0))
end function
public static double code(double a, double b, double eps) {
return (eps * (Math.exp(((a + b) * eps)) - 1.0)) / ((Math.exp((a * eps)) - 1.0) * (Math.exp((b * eps)) - 1.0));
}
def code(a, b, eps): return (eps * (math.exp(((a + b) * eps)) - 1.0)) / ((math.exp((a * eps)) - 1.0) * (math.exp((b * eps)) - 1.0))
function code(a, b, eps) return Float64(Float64(eps * Float64(exp(Float64(Float64(a + b) * eps)) - 1.0)) / Float64(Float64(exp(Float64(a * eps)) - 1.0) * Float64(exp(Float64(b * eps)) - 1.0))) end
function tmp = code(a, b, eps) tmp = (eps * (exp(((a + b) * eps)) - 1.0)) / ((exp((a * eps)) - 1.0) * (exp((b * eps)) - 1.0)); end
code[a_, b_, eps_] := N[(N[(eps * N[(N[Exp[N[(N[(a + b), $MachinePrecision] * eps), $MachinePrecision]], $MachinePrecision] - 1.0), $MachinePrecision]), $MachinePrecision] / N[(N[(N[Exp[N[(a * eps), $MachinePrecision]], $MachinePrecision] - 1.0), $MachinePrecision] * N[(N[Exp[N[(b * eps), $MachinePrecision]], $MachinePrecision] - 1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\varepsilon \cdot \left(e^{\left(a + b\right) \cdot \varepsilon} - 1\right)}{\left(e^{a \cdot \varepsilon} - 1\right) \cdot \left(e^{b \cdot \varepsilon} - 1\right)}
\end{array}
(FPCore (a b eps) :precision binary64 (+ (/ 1.0 a) (/ 1.0 b)))
double code(double a, double b, double eps) {
return (1.0 / a) + (1.0 / b);
}
real(8) function code(a, b, eps)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: eps
code = (1.0d0 / a) + (1.0d0 / b)
end function
public static double code(double a, double b, double eps) {
return (1.0 / a) + (1.0 / b);
}
def code(a, b, eps): return (1.0 / a) + (1.0 / b)
function code(a, b, eps) return Float64(Float64(1.0 / a) + Float64(1.0 / b)) end
function tmp = code(a, b, eps) tmp = (1.0 / a) + (1.0 / b); end
code[a_, b_, eps_] := N[(N[(1.0 / a), $MachinePrecision] + N[(1.0 / b), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{1}{a} + \frac{1}{b}
\end{array}
Initial program 0.2%
times-frac0.2%
expm1-def0.2%
*-commutative0.2%
expm1-def2.8%
*-commutative2.8%
expm1-def43.1%
*-commutative43.1%
Simplified43.1%
Taylor expanded in eps around 0 60.8%
Taylor expanded in a around 0 100.0%
Final simplification100.0%
(FPCore (a b eps) :precision binary64 (if (<= a -3.6e-147) (/ 1.0 b) (/ 1.0 a)))
double code(double a, double b, double eps) {
double tmp;
if (a <= -3.6e-147) {
tmp = 1.0 / b;
} else {
tmp = 1.0 / a;
}
return tmp;
}
real(8) function code(a, b, eps)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: eps
real(8) :: tmp
if (a <= (-3.6d-147)) then
tmp = 1.0d0 / b
else
tmp = 1.0d0 / a
end if
code = tmp
end function
public static double code(double a, double b, double eps) {
double tmp;
if (a <= -3.6e-147) {
tmp = 1.0 / b;
} else {
tmp = 1.0 / a;
}
return tmp;
}
def code(a, b, eps): tmp = 0 if a <= -3.6e-147: tmp = 1.0 / b else: tmp = 1.0 / a return tmp
function code(a, b, eps) tmp = 0.0 if (a <= -3.6e-147) tmp = Float64(1.0 / b); else tmp = Float64(1.0 / a); end return tmp end
function tmp_2 = code(a, b, eps) tmp = 0.0; if (a <= -3.6e-147) tmp = 1.0 / b; else tmp = 1.0 / a; end tmp_2 = tmp; end
code[a_, b_, eps_] := If[LessEqual[a, -3.6e-147], N[(1.0 / b), $MachinePrecision], N[(1.0 / a), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;a \leq -3.6 \cdot 10^{-147}:\\
\;\;\;\;\frac{1}{b}\\
\mathbf{else}:\\
\;\;\;\;\frac{1}{a}\\
\end{array}
\end{array}
if a < -3.60000000000000012e-147Initial program 0.4%
times-frac0.4%
expm1-def0.4%
*-commutative0.4%
expm1-def3.4%
*-commutative3.4%
expm1-def71.3%
*-commutative71.3%
Simplified71.3%
Taylor expanded in b around 0 84.4%
if -3.60000000000000012e-147 < a Initial program 0.0%
times-frac0.0%
expm1-def0.0%
*-commutative0.0%
expm1-def2.3%
*-commutative2.3%
expm1-def15.8%
*-commutative15.8%
Simplified15.8%
Taylor expanded in eps around 0 46.1%
Taylor expanded in a around 0 81.4%
Final simplification82.9%
(FPCore (a b eps) :precision binary64 (/ 1.0 a))
double code(double a, double b, double eps) {
return 1.0 / a;
}
real(8) function code(a, b, eps)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: eps
code = 1.0d0 / a
end function
public static double code(double a, double b, double eps) {
return 1.0 / a;
}
def code(a, b, eps): return 1.0 / a
function code(a, b, eps) return Float64(1.0 / a) end
function tmp = code(a, b, eps) tmp = 1.0 / a; end
code[a_, b_, eps_] := N[(1.0 / a), $MachinePrecision]
\begin{array}{l}
\\
\frac{1}{a}
\end{array}
Initial program 0.2%
times-frac0.2%
expm1-def0.2%
*-commutative0.2%
expm1-def2.8%
*-commutative2.8%
expm1-def43.1%
*-commutative43.1%
Simplified43.1%
Taylor expanded in eps around 0 60.8%
Taylor expanded in a around 0 48.4%
Final simplification48.4%
(FPCore (a b eps) :precision binary64 (+ (/ 1.0 a) (/ 1.0 b)))
double code(double a, double b, double eps) {
return (1.0 / a) + (1.0 / b);
}
real(8) function code(a, b, eps)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: eps
code = (1.0d0 / a) + (1.0d0 / b)
end function
public static double code(double a, double b, double eps) {
return (1.0 / a) + (1.0 / b);
}
def code(a, b, eps): return (1.0 / a) + (1.0 / b)
function code(a, b, eps) return Float64(Float64(1.0 / a) + Float64(1.0 / b)) end
function tmp = code(a, b, eps) tmp = (1.0 / a) + (1.0 / b); end
code[a_, b_, eps_] := N[(N[(1.0 / a), $MachinePrecision] + N[(1.0 / b), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{1}{a} + \frac{1}{b}
\end{array}
herbie shell --seed 2023320
(FPCore (a b eps)
:name "expq3 (problem 3.4.2)"
:precision binary64
:pre (and (and (and (<= -710.0 a) (<= a b)) (<= b 710.0)) (and (<= (* 1e-27 (fabs a)) eps) (<= eps (fabs a))))
:herbie-target
(+ (/ 1.0 a) (/ 1.0 b))
(/ (* eps (- (exp (* (+ a b) eps)) 1.0)) (* (- (exp (* a eps)) 1.0) (- (exp (* b eps)) 1.0))))