
(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 4 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}
(FPCore (a b eps)
:precision binary64
(if (<= a -6.9e-202)
(/ 1.0 b)
(if (or (<= a -1e-210) (not (<= a -1.15e-227)))
(/ 1.0 a)
(* (/ 1.0 a) (/ a b)))))
double code(double a, double b, double eps) {
double tmp;
if (a <= -6.9e-202) {
tmp = 1.0 / b;
} else if ((a <= -1e-210) || !(a <= -1.15e-227)) {
tmp = 1.0 / a;
} else {
tmp = (1.0 / a) * (a / b);
}
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 <= (-6.9d-202)) then
tmp = 1.0d0 / b
else if ((a <= (-1d-210)) .or. (.not. (a <= (-1.15d-227)))) then
tmp = 1.0d0 / a
else
tmp = (1.0d0 / a) * (a / b)
end if
code = tmp
end function
public static double code(double a, double b, double eps) {
double tmp;
if (a <= -6.9e-202) {
tmp = 1.0 / b;
} else if ((a <= -1e-210) || !(a <= -1.15e-227)) {
tmp = 1.0 / a;
} else {
tmp = (1.0 / a) * (a / b);
}
return tmp;
}
def code(a, b, eps): tmp = 0 if a <= -6.9e-202: tmp = 1.0 / b elif (a <= -1e-210) or not (a <= -1.15e-227): tmp = 1.0 / a else: tmp = (1.0 / a) * (a / b) return tmp
function code(a, b, eps) tmp = 0.0 if (a <= -6.9e-202) tmp = Float64(1.0 / b); elseif ((a <= -1e-210) || !(a <= -1.15e-227)) tmp = Float64(1.0 / a); else tmp = Float64(Float64(1.0 / a) * Float64(a / b)); end return tmp end
function tmp_2 = code(a, b, eps) tmp = 0.0; if (a <= -6.9e-202) tmp = 1.0 / b; elseif ((a <= -1e-210) || ~((a <= -1.15e-227))) tmp = 1.0 / a; else tmp = (1.0 / a) * (a / b); end tmp_2 = tmp; end
code[a_, b_, eps_] := If[LessEqual[a, -6.9e-202], N[(1.0 / b), $MachinePrecision], If[Or[LessEqual[a, -1e-210], N[Not[LessEqual[a, -1.15e-227]], $MachinePrecision]], N[(1.0 / a), $MachinePrecision], N[(N[(1.0 / a), $MachinePrecision] * N[(a / b), $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;a \leq -6.9 \cdot 10^{-202}:\\
\;\;\;\;\frac{1}{b}\\
\mathbf{elif}\;a \leq -1 \cdot 10^{-210} \lor \neg \left(a \leq -1.15 \cdot 10^{-227}\right):\\
\;\;\;\;\frac{1}{a}\\
\mathbf{else}:\\
\;\;\;\;\frac{1}{a} \cdot \frac{a}{b}\\
\end{array}
\end{array}
(FPCore (a b eps) :precision binary64 (if (or (<= a -5.7e-202) (and (not (<= a -5.2e-212)) (<= a -1.15e-227))) (/ 1.0 b) (/ 1.0 a)))
double code(double a, double b, double eps) {
double tmp;
if ((a <= -5.7e-202) || (!(a <= -5.2e-212) && (a <= -1.15e-227))) {
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 <= (-5.7d-202)) .or. (.not. (a <= (-5.2d-212))) .and. (a <= (-1.15d-227))) 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 <= -5.7e-202) || (!(a <= -5.2e-212) && (a <= -1.15e-227))) {
tmp = 1.0 / b;
} else {
tmp = 1.0 / a;
}
return tmp;
}
def code(a, b, eps): tmp = 0 if (a <= -5.7e-202) or (not (a <= -5.2e-212) and (a <= -1.15e-227)): tmp = 1.0 / b else: tmp = 1.0 / a return tmp
function code(a, b, eps) tmp = 0.0 if ((a <= -5.7e-202) || (!(a <= -5.2e-212) && (a <= -1.15e-227))) 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 <= -5.7e-202) || (~((a <= -5.2e-212)) && (a <= -1.15e-227))) tmp = 1.0 / b; else tmp = 1.0 / a; end tmp_2 = tmp; end
code[a_, b_, eps_] := If[Or[LessEqual[a, -5.7e-202], And[N[Not[LessEqual[a, -5.2e-212]], $MachinePrecision], LessEqual[a, -1.15e-227]]], N[(1.0 / b), $MachinePrecision], N[(1.0 / a), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;a \leq -5.7 \cdot 10^{-202} \lor \neg \left(a \leq -5.2 \cdot 10^{-212}\right) \land a \leq -1.15 \cdot 10^{-227}:\\
\;\;\;\;\frac{1}{b}\\
\mathbf{else}:\\
\;\;\;\;\frac{1}{a}\\
\end{array}
\end{array}
(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}
(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 2023350
(FPCore (a b eps)
:name "expq3 (problem 3.4.2)"
:precision binary64
:pre (and (and (<= (fabs a) 710.0) (<= (fabs b) 710.0)) (and (<= (* 1e-27 (fmin (fabs a) (fabs b))) eps) (<= eps (fmin (fabs a) (fabs b)))))
: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))))