symmetry log of sum of exp

Percentage Accurate: 53.0% → 98.2%
Time: 14.5s
Alternatives: 12
Speedup: 1.5×

Specification

?
\[\begin{array}{l} \\ \log \left(e^{a} + e^{b}\right) \end{array} \]
(FPCore (a b) :precision binary64 (log (+ (exp a) (exp b))))
double code(double a, double b) {
	return log((exp(a) + exp(b)));
}
real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = log((exp(a) + exp(b)))
end function
public static double code(double a, double b) {
	return Math.log((Math.exp(a) + Math.exp(b)));
}
def code(a, b):
	return math.log((math.exp(a) + math.exp(b)))
function code(a, b)
	return log(Float64(exp(a) + exp(b)))
end
function tmp = code(a, b)
	tmp = log((exp(a) + exp(b)));
end
code[a_, b_] := N[Log[N[(N[Exp[a], $MachinePrecision] + N[Exp[b], $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\log \left(e^{a} + e^{b}\right)
\end{array}

Sampling outcomes in binary64 precision:

Local Percentage Accuracy vs ?

The average percentage accuracy by input value. Horizontal axis shows value of an input variable; the variable is choosen in the title. Vertical axis is accuracy; higher is better. Red represent the original program, while blue represents Herbie's suggestion. These can be toggled with buttons below the plot. The line is an average while dots represent individual samples.

Accuracy vs Speed?

Herbie found 12 alternatives:

AlternativeAccuracySpeedup
The accuracy (vertical axis) and speed (horizontal axis) of each alternatives. Up and to the right is better. The red square shows the initial program, and each blue circle shows an alternative.The line shows the best available speed-accuracy tradeoffs.

Initial Program: 53.0% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \log \left(e^{a} + e^{b}\right) \end{array} \]
(FPCore (a b) :precision binary64 (log (+ (exp a) (exp b))))
double code(double a, double b) {
	return log((exp(a) + exp(b)));
}
real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = log((exp(a) + exp(b)))
end function
public static double code(double a, double b) {
	return Math.log((Math.exp(a) + Math.exp(b)));
}
def code(a, b):
	return math.log((math.exp(a) + math.exp(b)))
function code(a, b)
	return log(Float64(exp(a) + exp(b)))
end
function tmp = code(a, b)
	tmp = log((exp(a) + exp(b)));
end
code[a_, b_] := N[Log[N[(N[Exp[a], $MachinePrecision] + N[Exp[b], $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\log \left(e^{a} + e^{b}\right)
\end{array}

Alternative 1: 98.2% accurate, 1.0× speedup?

\[\begin{array}{l} [a, b] = \mathsf{sort}([a, b])\\ \\ \mathsf{log1p}\left(e^{a} + \mathsf{expm1}\left(b\right)\right) \end{array} \]
NOTE: a and b should be sorted in increasing order before calling this function.
(FPCore (a b) :precision binary64 (log1p (+ (exp a) (expm1 b))))
assert(a < b);
double code(double a, double b) {
	return log1p((exp(a) + expm1(b)));
}
assert a < b;
public static double code(double a, double b) {
	return Math.log1p((Math.exp(a) + Math.expm1(b)));
}
[a, b] = sort([a, b])
def code(a, b):
	return math.log1p((math.exp(a) + math.expm1(b)))
a, b = sort([a, b])
function code(a, b)
	return log1p(Float64(exp(a) + expm1(b)))
end
NOTE: a and b should be sorted in increasing order before calling this function.
code[a_, b_] := N[Log[1 + N[(N[Exp[a], $MachinePrecision] + N[(Exp[b] - 1), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}
[a, b] = \mathsf{sort}([a, b])\\
\\
\mathsf{log1p}\left(e^{a} + \mathsf{expm1}\left(b\right)\right)
\end{array}
Derivation
  1. Initial program 49.7%

    \[\log \left(e^{a} + e^{b}\right) \]
  2. Step-by-step derivation
    1. add-sqr-sqrt48.6%

      \[\leadsto \log \color{blue}{\left(\sqrt{e^{a} + e^{b}} \cdot \sqrt{e^{a} + e^{b}}\right)} \]
    2. log-prod49.0%

      \[\leadsto \color{blue}{\log \left(\sqrt{e^{a} + e^{b}}\right) + \log \left(\sqrt{e^{a} + e^{b}}\right)} \]
  3. Applied egg-rr49.0%

    \[\leadsto \color{blue}{\log \left(\sqrt{e^{a} + e^{b}}\right) + \log \left(\sqrt{e^{a} + e^{b}}\right)} \]
  4. Step-by-step derivation
    1. log-prod48.6%

      \[\leadsto \color{blue}{\log \left(\sqrt{e^{a} + e^{b}} \cdot \sqrt{e^{a} + e^{b}}\right)} \]
    2. rem-square-sqrt49.7%

      \[\leadsto \log \color{blue}{\left(e^{a} + e^{b}\right)} \]
    3. log1p-expm149.7%

      \[\leadsto \color{blue}{\mathsf{log1p}\left(\mathsf{expm1}\left(\log \left(e^{a} + e^{b}\right)\right)\right)} \]
    4. expm1-def49.7%

      \[\leadsto \mathsf{log1p}\left(\color{blue}{e^{\log \left(e^{a} + e^{b}\right)} - 1}\right) \]
    5. rem-exp-log49.7%

      \[\leadsto \mathsf{log1p}\left(\color{blue}{\left(e^{a} + e^{b}\right)} - 1\right) \]
    6. associate--l+50.3%

      \[\leadsto \mathsf{log1p}\left(\color{blue}{e^{a} + \left(e^{b} - 1\right)}\right) \]
    7. expm1-def72.3%

      \[\leadsto \mathsf{log1p}\left(e^{a} + \color{blue}{\mathsf{expm1}\left(b\right)}\right) \]
  5. Simplified72.3%

    \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a} + \mathsf{expm1}\left(b\right)\right)} \]
  6. Final simplification72.3%

    \[\leadsto \mathsf{log1p}\left(e^{a} + \mathsf{expm1}\left(b\right)\right) \]

Alternative 2: 98.7% accurate, 0.7× speedup?

\[\begin{array}{l} [a, b] = \mathsf{sort}([a, b])\\ \\ \begin{array}{l} \mathbf{if}\;e^{a} \leq 5 \cdot 10^{-78}:\\ \;\;\;\;\frac{b}{e^{a} + 1}\\ \mathbf{else}:\\ \;\;\;\;\log \left(e^{a} + e^{b}\right)\\ \end{array} \end{array} \]
NOTE: a and b should be sorted in increasing order before calling this function.
(FPCore (a b)
 :precision binary64
 (if (<= (exp a) 5e-78) (/ b (+ (exp a) 1.0)) (log (+ (exp a) (exp b)))))
assert(a < b);
double code(double a, double b) {
	double tmp;
	if (exp(a) <= 5e-78) {
		tmp = b / (exp(a) + 1.0);
	} else {
		tmp = log((exp(a) + exp(b)));
	}
	return tmp;
}
NOTE: a and b should be sorted in increasing order before calling this function.
real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    real(8) :: tmp
    if (exp(a) <= 5d-78) then
        tmp = b / (exp(a) + 1.0d0)
    else
        tmp = log((exp(a) + exp(b)))
    end if
    code = tmp
end function
assert a < b;
public static double code(double a, double b) {
	double tmp;
	if (Math.exp(a) <= 5e-78) {
		tmp = b / (Math.exp(a) + 1.0);
	} else {
		tmp = Math.log((Math.exp(a) + Math.exp(b)));
	}
	return tmp;
}
[a, b] = sort([a, b])
def code(a, b):
	tmp = 0
	if math.exp(a) <= 5e-78:
		tmp = b / (math.exp(a) + 1.0)
	else:
		tmp = math.log((math.exp(a) + math.exp(b)))
	return tmp
a, b = sort([a, b])
function code(a, b)
	tmp = 0.0
	if (exp(a) <= 5e-78)
		tmp = Float64(b / Float64(exp(a) + 1.0));
	else
		tmp = log(Float64(exp(a) + exp(b)));
	end
	return tmp
end
a, b = num2cell(sort([a, b])){:}
function tmp_2 = code(a, b)
	tmp = 0.0;
	if (exp(a) <= 5e-78)
		tmp = b / (exp(a) + 1.0);
	else
		tmp = log((exp(a) + exp(b)));
	end
	tmp_2 = tmp;
end
NOTE: a and b should be sorted in increasing order before calling this function.
code[a_, b_] := If[LessEqual[N[Exp[a], $MachinePrecision], 5e-78], N[(b / N[(N[Exp[a], $MachinePrecision] + 1.0), $MachinePrecision]), $MachinePrecision], N[Log[N[(N[Exp[a], $MachinePrecision] + N[Exp[b], $MachinePrecision]), $MachinePrecision]], $MachinePrecision]]
\begin{array}{l}
[a, b] = \mathsf{sort}([a, b])\\
\\
\begin{array}{l}
\mathbf{if}\;e^{a} \leq 5 \cdot 10^{-78}:\\
\;\;\;\;\frac{b}{e^{a} + 1}\\

\mathbf{else}:\\
\;\;\;\;\log \left(e^{a} + e^{b}\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (exp.f64 a) < 4.9999999999999996e-78

    1. Initial program 10.4%

      \[\log \left(e^{a} + e^{b}\right) \]
    2. Taylor expanded in b around 0 98.6%

      \[\leadsto \color{blue}{\log \left(1 + e^{a}\right) + \frac{b}{1 + e^{a}}} \]
    3. Step-by-step derivation
      1. log1p-def100.0%

        \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a}\right)} + \frac{b}{1 + e^{a}} \]
    4. Simplified100.0%

      \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a}\right) + \frac{b}{1 + e^{a}}} \]
    5. Taylor expanded in b around inf 98.6%

      \[\leadsto \color{blue}{\frac{b}{1 + e^{a}}} \]

    if 4.9999999999999996e-78 < (exp.f64 a)

    1. Initial program 62.8%

      \[\log \left(e^{a} + e^{b}\right) \]
  3. Recombined 2 regimes into one program.
  4. Final simplification71.8%

    \[\leadsto \begin{array}{l} \mathbf{if}\;e^{a} \leq 5 \cdot 10^{-78}:\\ \;\;\;\;\frac{b}{e^{a} + 1}\\ \mathbf{else}:\\ \;\;\;\;\log \left(e^{a} + e^{b}\right)\\ \end{array} \]

Alternative 3: 98.1% accurate, 1.0× speedup?

\[\begin{array}{l} [a, b] = \mathsf{sort}([a, b])\\ \\ \begin{array}{l} \mathbf{if}\;e^{a} \leq 2 \cdot 10^{-8}:\\ \;\;\;\;\frac{b}{e^{a} + 1}\\ \mathbf{else}:\\ \;\;\;\;\mathsf{log1p}\left(a + e^{b}\right)\\ \end{array} \end{array} \]
NOTE: a and b should be sorted in increasing order before calling this function.
(FPCore (a b)
 :precision binary64
 (if (<= (exp a) 2e-8) (/ b (+ (exp a) 1.0)) (log1p (+ a (exp b)))))
assert(a < b);
double code(double a, double b) {
	double tmp;
	if (exp(a) <= 2e-8) {
		tmp = b / (exp(a) + 1.0);
	} else {
		tmp = log1p((a + exp(b)));
	}
	return tmp;
}
assert a < b;
public static double code(double a, double b) {
	double tmp;
	if (Math.exp(a) <= 2e-8) {
		tmp = b / (Math.exp(a) + 1.0);
	} else {
		tmp = Math.log1p((a + Math.exp(b)));
	}
	return tmp;
}
[a, b] = sort([a, b])
def code(a, b):
	tmp = 0
	if math.exp(a) <= 2e-8:
		tmp = b / (math.exp(a) + 1.0)
	else:
		tmp = math.log1p((a + math.exp(b)))
	return tmp
a, b = sort([a, b])
function code(a, b)
	tmp = 0.0
	if (exp(a) <= 2e-8)
		tmp = Float64(b / Float64(exp(a) + 1.0));
	else
		tmp = log1p(Float64(a + exp(b)));
	end
	return tmp
end
NOTE: a and b should be sorted in increasing order before calling this function.
code[a_, b_] := If[LessEqual[N[Exp[a], $MachinePrecision], 2e-8], N[(b / N[(N[Exp[a], $MachinePrecision] + 1.0), $MachinePrecision]), $MachinePrecision], N[Log[1 + N[(a + N[Exp[b], $MachinePrecision]), $MachinePrecision]], $MachinePrecision]]
\begin{array}{l}
[a, b] = \mathsf{sort}([a, b])\\
\\
\begin{array}{l}
\mathbf{if}\;e^{a} \leq 2 \cdot 10^{-8}:\\
\;\;\;\;\frac{b}{e^{a} + 1}\\

\mathbf{else}:\\
\;\;\;\;\mathsf{log1p}\left(a + e^{b}\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (exp.f64 a) < 2e-8

    1. Initial program 11.2%

      \[\log \left(e^{a} + e^{b}\right) \]
    2. Taylor expanded in b around 0 98.1%

      \[\leadsto \color{blue}{\log \left(1 + e^{a}\right) + \frac{b}{1 + e^{a}}} \]
    3. Step-by-step derivation
      1. log1p-def100.0%

        \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a}\right)} + \frac{b}{1 + e^{a}} \]
    4. Simplified100.0%

      \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a}\right) + \frac{b}{1 + e^{a}}} \]
    5. Taylor expanded in b around inf 97.1%

      \[\leadsto \color{blue}{\frac{b}{1 + e^{a}}} \]

    if 2e-8 < (exp.f64 a)

    1. Initial program 62.8%

      \[\log \left(e^{a} + e^{b}\right) \]
    2. Taylor expanded in a around 0 61.8%

      \[\leadsto \log \color{blue}{\left(1 + \left(a + e^{b}\right)\right)} \]
    3. Step-by-step derivation
      1. associate-+r+61.8%

        \[\leadsto \log \color{blue}{\left(\left(1 + a\right) + e^{b}\right)} \]
      2. +-commutative61.8%

        \[\leadsto \log \color{blue}{\left(e^{b} + \left(1 + a\right)\right)} \]
    4. Simplified61.8%

      \[\leadsto \log \color{blue}{\left(e^{b} + \left(1 + a\right)\right)} \]
    5. Taylor expanded in b around inf 61.8%

      \[\leadsto \color{blue}{\log \left(1 + \left(a + e^{b}\right)\right)} \]
    6. Step-by-step derivation
      1. log1p-def98.3%

        \[\leadsto \color{blue}{\mathsf{log1p}\left(a + e^{b}\right)} \]
    7. Simplified98.3%

      \[\leadsto \color{blue}{\mathsf{log1p}\left(a + e^{b}\right)} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification98.0%

    \[\leadsto \begin{array}{l} \mathbf{if}\;e^{a} \leq 2 \cdot 10^{-8}:\\ \;\;\;\;\frac{b}{e^{a} + 1}\\ \mathbf{else}:\\ \;\;\;\;\mathsf{log1p}\left(a + e^{b}\right)\\ \end{array} \]

Alternative 4: 97.5% accurate, 1.0× speedup?

\[\begin{array}{l} [a, b] = \mathsf{sort}([a, b])\\ \\ \begin{array}{l} \mathbf{if}\;e^{a} \leq 5 \cdot 10^{-297}:\\ \;\;\;\;\frac{b}{e^{a} + 1}\\ \mathbf{else}:\\ \;\;\;\;\mathsf{log1p}\left(e^{a}\right)\\ \end{array} \end{array} \]
NOTE: a and b should be sorted in increasing order before calling this function.
(FPCore (a b)
 :precision binary64
 (if (<= (exp a) 5e-297) (/ b (+ (exp a) 1.0)) (log1p (exp a))))
assert(a < b);
double code(double a, double b) {
	double tmp;
	if (exp(a) <= 5e-297) {
		tmp = b / (exp(a) + 1.0);
	} else {
		tmp = log1p(exp(a));
	}
	return tmp;
}
assert a < b;
public static double code(double a, double b) {
	double tmp;
	if (Math.exp(a) <= 5e-297) {
		tmp = b / (Math.exp(a) + 1.0);
	} else {
		tmp = Math.log1p(Math.exp(a));
	}
	return tmp;
}
[a, b] = sort([a, b])
def code(a, b):
	tmp = 0
	if math.exp(a) <= 5e-297:
		tmp = b / (math.exp(a) + 1.0)
	else:
		tmp = math.log1p(math.exp(a))
	return tmp
a, b = sort([a, b])
function code(a, b)
	tmp = 0.0
	if (exp(a) <= 5e-297)
		tmp = Float64(b / Float64(exp(a) + 1.0));
	else
		tmp = log1p(exp(a));
	end
	return tmp
end
NOTE: a and b should be sorted in increasing order before calling this function.
code[a_, b_] := If[LessEqual[N[Exp[a], $MachinePrecision], 5e-297], N[(b / N[(N[Exp[a], $MachinePrecision] + 1.0), $MachinePrecision]), $MachinePrecision], N[Log[1 + N[Exp[a], $MachinePrecision]], $MachinePrecision]]
\begin{array}{l}
[a, b] = \mathsf{sort}([a, b])\\
\\
\begin{array}{l}
\mathbf{if}\;e^{a} \leq 5 \cdot 10^{-297}:\\
\;\;\;\;\frac{b}{e^{a} + 1}\\

\mathbf{else}:\\
\;\;\;\;\mathsf{log1p}\left(e^{a}\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (exp.f64 a) < 5e-297

    1. Initial program 10.5%

      \[\log \left(e^{a} + e^{b}\right) \]
    2. Taylor expanded in b around 0 100.0%

      \[\leadsto \color{blue}{\log \left(1 + e^{a}\right) + \frac{b}{1 + e^{a}}} \]
    3. Step-by-step derivation
      1. log1p-def100.0%

        \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a}\right)} + \frac{b}{1 + e^{a}} \]
    4. Simplified100.0%

      \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a}\right) + \frac{b}{1 + e^{a}}} \]
    5. Taylor expanded in b around inf 100.0%

      \[\leadsto \color{blue}{\frac{b}{1 + e^{a}}} \]

    if 5e-297 < (exp.f64 a)

    1. Initial program 62.5%

      \[\log \left(e^{a} + e^{b}\right) \]
    2. Taylor expanded in b around 0 59.7%

      \[\leadsto \color{blue}{\log \left(1 + e^{a}\right)} \]
    3. Step-by-step derivation
      1. log1p-def60.4%

        \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a}\right)} \]
    4. Simplified60.4%

      \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a}\right)} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification70.2%

    \[\leadsto \begin{array}{l} \mathbf{if}\;e^{a} \leq 5 \cdot 10^{-297}:\\ \;\;\;\;\frac{b}{e^{a} + 1}\\ \mathbf{else}:\\ \;\;\;\;\mathsf{log1p}\left(e^{a}\right)\\ \end{array} \]

Alternative 5: 97.6% accurate, 1.0× speedup?

\[\begin{array}{l} [a, b] = \mathsf{sort}([a, b])\\ \\ \begin{array}{l} \mathbf{if}\;e^{a} \leq 5 \cdot 10^{-78}:\\ \;\;\;\;\frac{b}{e^{a} + 1}\\ \mathbf{else}:\\ \;\;\;\;\mathsf{log1p}\left(e^{b}\right)\\ \end{array} \end{array} \]
NOTE: a and b should be sorted in increasing order before calling this function.
(FPCore (a b)
 :precision binary64
 (if (<= (exp a) 5e-78) (/ b (+ (exp a) 1.0)) (log1p (exp b))))
assert(a < b);
double code(double a, double b) {
	double tmp;
	if (exp(a) <= 5e-78) {
		tmp = b / (exp(a) + 1.0);
	} else {
		tmp = log1p(exp(b));
	}
	return tmp;
}
assert a < b;
public static double code(double a, double b) {
	double tmp;
	if (Math.exp(a) <= 5e-78) {
		tmp = b / (Math.exp(a) + 1.0);
	} else {
		tmp = Math.log1p(Math.exp(b));
	}
	return tmp;
}
[a, b] = sort([a, b])
def code(a, b):
	tmp = 0
	if math.exp(a) <= 5e-78:
		tmp = b / (math.exp(a) + 1.0)
	else:
		tmp = math.log1p(math.exp(b))
	return tmp
a, b = sort([a, b])
function code(a, b)
	tmp = 0.0
	if (exp(a) <= 5e-78)
		tmp = Float64(b / Float64(exp(a) + 1.0));
	else
		tmp = log1p(exp(b));
	end
	return tmp
end
NOTE: a and b should be sorted in increasing order before calling this function.
code[a_, b_] := If[LessEqual[N[Exp[a], $MachinePrecision], 5e-78], N[(b / N[(N[Exp[a], $MachinePrecision] + 1.0), $MachinePrecision]), $MachinePrecision], N[Log[1 + N[Exp[b], $MachinePrecision]], $MachinePrecision]]
\begin{array}{l}
[a, b] = \mathsf{sort}([a, b])\\
\\
\begin{array}{l}
\mathbf{if}\;e^{a} \leq 5 \cdot 10^{-78}:\\
\;\;\;\;\frac{b}{e^{a} + 1}\\

\mathbf{else}:\\
\;\;\;\;\mathsf{log1p}\left(e^{b}\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (exp.f64 a) < 4.9999999999999996e-78

    1. Initial program 10.4%

      \[\log \left(e^{a} + e^{b}\right) \]
    2. Taylor expanded in b around 0 98.6%

      \[\leadsto \color{blue}{\log \left(1 + e^{a}\right) + \frac{b}{1 + e^{a}}} \]
    3. Step-by-step derivation
      1. log1p-def100.0%

        \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a}\right)} + \frac{b}{1 + e^{a}} \]
    4. Simplified100.0%

      \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a}\right) + \frac{b}{1 + e^{a}}} \]
    5. Taylor expanded in b around inf 98.6%

      \[\leadsto \color{blue}{\frac{b}{1 + e^{a}}} \]

    if 4.9999999999999996e-78 < (exp.f64 a)

    1. Initial program 62.8%

      \[\log \left(e^{a} + e^{b}\right) \]
    2. Taylor expanded in a around 0 60.2%

      \[\leadsto \color{blue}{\log \left(1 + e^{b}\right)} \]
    3. Step-by-step derivation
      1. log1p-def60.2%

        \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{b}\right)} \]
    4. Simplified60.2%

      \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{b}\right)} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification69.8%

    \[\leadsto \begin{array}{l} \mathbf{if}\;e^{a} \leq 5 \cdot 10^{-78}:\\ \;\;\;\;\frac{b}{e^{a} + 1}\\ \mathbf{else}:\\ \;\;\;\;\mathsf{log1p}\left(e^{b}\right)\\ \end{array} \]

Alternative 6: 97.1% accurate, 1.4× speedup?

\[\begin{array}{l} [a, b] = \mathsf{sort}([a, b])\\ \\ \begin{array}{l} \mathbf{if}\;e^{a} \leq 5 \cdot 10^{-78}:\\ \;\;\;\;\frac{b}{e^{a} + 1}\\ \mathbf{else}:\\ \;\;\;\;\log \left(b + \left(2 + 0.5 \cdot \left(b \cdot b\right)\right)\right)\\ \end{array} \end{array} \]
NOTE: a and b should be sorted in increasing order before calling this function.
(FPCore (a b)
 :precision binary64
 (if (<= (exp a) 5e-78)
   (/ b (+ (exp a) 1.0))
   (log (+ b (+ 2.0 (* 0.5 (* b b)))))))
assert(a < b);
double code(double a, double b) {
	double tmp;
	if (exp(a) <= 5e-78) {
		tmp = b / (exp(a) + 1.0);
	} else {
		tmp = log((b + (2.0 + (0.5 * (b * b)))));
	}
	return tmp;
}
NOTE: a and b should be sorted in increasing order before calling this function.
real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    real(8) :: tmp
    if (exp(a) <= 5d-78) then
        tmp = b / (exp(a) + 1.0d0)
    else
        tmp = log((b + (2.0d0 + (0.5d0 * (b * b)))))
    end if
    code = tmp
end function
assert a < b;
public static double code(double a, double b) {
	double tmp;
	if (Math.exp(a) <= 5e-78) {
		tmp = b / (Math.exp(a) + 1.0);
	} else {
		tmp = Math.log((b + (2.0 + (0.5 * (b * b)))));
	}
	return tmp;
}
[a, b] = sort([a, b])
def code(a, b):
	tmp = 0
	if math.exp(a) <= 5e-78:
		tmp = b / (math.exp(a) + 1.0)
	else:
		tmp = math.log((b + (2.0 + (0.5 * (b * b)))))
	return tmp
a, b = sort([a, b])
function code(a, b)
	tmp = 0.0
	if (exp(a) <= 5e-78)
		tmp = Float64(b / Float64(exp(a) + 1.0));
	else
		tmp = log(Float64(b + Float64(2.0 + Float64(0.5 * Float64(b * b)))));
	end
	return tmp
end
a, b = num2cell(sort([a, b])){:}
function tmp_2 = code(a, b)
	tmp = 0.0;
	if (exp(a) <= 5e-78)
		tmp = b / (exp(a) + 1.0);
	else
		tmp = log((b + (2.0 + (0.5 * (b * b)))));
	end
	tmp_2 = tmp;
end
NOTE: a and b should be sorted in increasing order before calling this function.
code[a_, b_] := If[LessEqual[N[Exp[a], $MachinePrecision], 5e-78], N[(b / N[(N[Exp[a], $MachinePrecision] + 1.0), $MachinePrecision]), $MachinePrecision], N[Log[N[(b + N[(2.0 + N[(0.5 * N[(b * b), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]]
\begin{array}{l}
[a, b] = \mathsf{sort}([a, b])\\
\\
\begin{array}{l}
\mathbf{if}\;e^{a} \leq 5 \cdot 10^{-78}:\\
\;\;\;\;\frac{b}{e^{a} + 1}\\

\mathbf{else}:\\
\;\;\;\;\log \left(b + \left(2 + 0.5 \cdot \left(b \cdot b\right)\right)\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (exp.f64 a) < 4.9999999999999996e-78

    1. Initial program 10.4%

      \[\log \left(e^{a} + e^{b}\right) \]
    2. Taylor expanded in b around 0 98.6%

      \[\leadsto \color{blue}{\log \left(1 + e^{a}\right) + \frac{b}{1 + e^{a}}} \]
    3. Step-by-step derivation
      1. log1p-def100.0%

        \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a}\right)} + \frac{b}{1 + e^{a}} \]
    4. Simplified100.0%

      \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a}\right) + \frac{b}{1 + e^{a}}} \]
    5. Taylor expanded in b around inf 98.6%

      \[\leadsto \color{blue}{\frac{b}{1 + e^{a}}} \]

    if 4.9999999999999996e-78 < (exp.f64 a)

    1. Initial program 62.8%

      \[\log \left(e^{a} + e^{b}\right) \]
    2. Taylor expanded in b around 0 60.3%

      \[\leadsto \log \color{blue}{\left(1 + \left(e^{a} + \left(b + 0.5 \cdot {b}^{2}\right)\right)\right)} \]
    3. Step-by-step derivation
      1. +-commutative60.3%

        \[\leadsto \log \color{blue}{\left(\left(e^{a} + \left(b + 0.5 \cdot {b}^{2}\right)\right) + 1\right)} \]
      2. associate-+r+60.3%

        \[\leadsto \log \left(\color{blue}{\left(\left(e^{a} + b\right) + 0.5 \cdot {b}^{2}\right)} + 1\right) \]
      3. associate-+l+60.3%

        \[\leadsto \log \color{blue}{\left(\left(e^{a} + b\right) + \left(0.5 \cdot {b}^{2} + 1\right)\right)} \]
      4. +-commutative60.3%

        \[\leadsto \log \left(\color{blue}{\left(b + e^{a}\right)} + \left(0.5 \cdot {b}^{2} + 1\right)\right) \]
      5. associate-+l+60.3%

        \[\leadsto \log \color{blue}{\left(b + \left(e^{a} + \left(0.5 \cdot {b}^{2} + 1\right)\right)\right)} \]
      6. fma-def60.3%

        \[\leadsto \log \left(b + \left(e^{a} + \color{blue}{\mathsf{fma}\left(0.5, {b}^{2}, 1\right)}\right)\right) \]
      7. unpow260.3%

        \[\leadsto \log \left(b + \left(e^{a} + \mathsf{fma}\left(0.5, \color{blue}{b \cdot b}, 1\right)\right)\right) \]
    4. Simplified60.3%

      \[\leadsto \log \color{blue}{\left(b + \left(e^{a} + \mathsf{fma}\left(0.5, b \cdot b, 1\right)\right)\right)} \]
    5. Taylor expanded in a around 0 58.2%

      \[\leadsto \log \left(b + \color{blue}{\left(2 + 0.5 \cdot {b}^{2}\right)}\right) \]
    6. Step-by-step derivation
      1. unpow258.2%

        \[\leadsto \log \left(b + \left(2 + 0.5 \cdot \color{blue}{\left(b \cdot b\right)}\right)\right) \]
    7. Simplified58.2%

      \[\leadsto \log \left(b + \color{blue}{\left(2 + 0.5 \cdot \left(b \cdot b\right)\right)}\right) \]
  3. Recombined 2 regimes into one program.
  4. Final simplification68.3%

    \[\leadsto \begin{array}{l} \mathbf{if}\;e^{a} \leq 5 \cdot 10^{-78}:\\ \;\;\;\;\frac{b}{e^{a} + 1}\\ \mathbf{else}:\\ \;\;\;\;\log \left(b + \left(2 + 0.5 \cdot \left(b \cdot b\right)\right)\right)\\ \end{array} \]

Alternative 7: 97.4% accurate, 1.5× speedup?

\[\begin{array}{l} [a, b] = \mathsf{sort}([a, b])\\ \\ \begin{array}{l} \mathbf{if}\;e^{a} \leq 2 \cdot 10^{-8}:\\ \;\;\;\;\frac{b}{e^{a} + 1}\\ \mathbf{else}:\\ \;\;\;\;\log \left(b + \left(a + 2\right)\right)\\ \end{array} \end{array} \]
NOTE: a and b should be sorted in increasing order before calling this function.
(FPCore (a b)
 :precision binary64
 (if (<= (exp a) 2e-8) (/ b (+ (exp a) 1.0)) (log (+ b (+ a 2.0)))))
assert(a < b);
double code(double a, double b) {
	double tmp;
	if (exp(a) <= 2e-8) {
		tmp = b / (exp(a) + 1.0);
	} else {
		tmp = log((b + (a + 2.0)));
	}
	return tmp;
}
NOTE: a and b should be sorted in increasing order before calling this function.
real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    real(8) :: tmp
    if (exp(a) <= 2d-8) then
        tmp = b / (exp(a) + 1.0d0)
    else
        tmp = log((b + (a + 2.0d0)))
    end if
    code = tmp
end function
assert a < b;
public static double code(double a, double b) {
	double tmp;
	if (Math.exp(a) <= 2e-8) {
		tmp = b / (Math.exp(a) + 1.0);
	} else {
		tmp = Math.log((b + (a + 2.0)));
	}
	return tmp;
}
[a, b] = sort([a, b])
def code(a, b):
	tmp = 0
	if math.exp(a) <= 2e-8:
		tmp = b / (math.exp(a) + 1.0)
	else:
		tmp = math.log((b + (a + 2.0)))
	return tmp
a, b = sort([a, b])
function code(a, b)
	tmp = 0.0
	if (exp(a) <= 2e-8)
		tmp = Float64(b / Float64(exp(a) + 1.0));
	else
		tmp = log(Float64(b + Float64(a + 2.0)));
	end
	return tmp
end
a, b = num2cell(sort([a, b])){:}
function tmp_2 = code(a, b)
	tmp = 0.0;
	if (exp(a) <= 2e-8)
		tmp = b / (exp(a) + 1.0);
	else
		tmp = log((b + (a + 2.0)));
	end
	tmp_2 = tmp;
end
NOTE: a and b should be sorted in increasing order before calling this function.
code[a_, b_] := If[LessEqual[N[Exp[a], $MachinePrecision], 2e-8], N[(b / N[(N[Exp[a], $MachinePrecision] + 1.0), $MachinePrecision]), $MachinePrecision], N[Log[N[(b + N[(a + 2.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]]
\begin{array}{l}
[a, b] = \mathsf{sort}([a, b])\\
\\
\begin{array}{l}
\mathbf{if}\;e^{a} \leq 2 \cdot 10^{-8}:\\
\;\;\;\;\frac{b}{e^{a} + 1}\\

\mathbf{else}:\\
\;\;\;\;\log \left(b + \left(a + 2\right)\right)\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (exp.f64 a) < 2e-8

    1. Initial program 11.2%

      \[\log \left(e^{a} + e^{b}\right) \]
    2. Taylor expanded in b around 0 98.1%

      \[\leadsto \color{blue}{\log \left(1 + e^{a}\right) + \frac{b}{1 + e^{a}}} \]
    3. Step-by-step derivation
      1. log1p-def100.0%

        \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a}\right)} + \frac{b}{1 + e^{a}} \]
    4. Simplified100.0%

      \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a}\right) + \frac{b}{1 + e^{a}}} \]
    5. Taylor expanded in b around inf 97.1%

      \[\leadsto \color{blue}{\frac{b}{1 + e^{a}}} \]

    if 2e-8 < (exp.f64 a)

    1. Initial program 62.8%

      \[\log \left(e^{a} + e^{b}\right) \]
    2. Taylor expanded in b around 0 58.9%

      \[\leadsto \log \color{blue}{\left(1 + \left(e^{a} + b\right)\right)} \]
    3. Step-by-step derivation
      1. associate-+r+58.9%

        \[\leadsto \log \color{blue}{\left(\left(1 + e^{a}\right) + b\right)} \]
      2. +-commutative58.9%

        \[\leadsto \log \left(\color{blue}{\left(e^{a} + 1\right)} + b\right) \]
      3. associate-+l+58.9%

        \[\leadsto \log \color{blue}{\left(e^{a} + \left(1 + b\right)\right)} \]
    4. Simplified58.9%

      \[\leadsto \log \color{blue}{\left(e^{a} + \left(1 + b\right)\right)} \]
    5. Taylor expanded in a around 0 57.9%

      \[\leadsto \log \color{blue}{\left(2 + \left(a + b\right)\right)} \]
    6. Step-by-step derivation
      1. +-commutative57.9%

        \[\leadsto \log \color{blue}{\left(\left(a + b\right) + 2\right)} \]
      2. +-commutative57.9%

        \[\leadsto \log \left(\color{blue}{\left(b + a\right)} + 2\right) \]
      3. associate-+l+57.9%

        \[\leadsto \log \color{blue}{\left(b + \left(a + 2\right)\right)} \]
    7. Simplified57.9%

      \[\leadsto \log \color{blue}{\left(b + \left(a + 2\right)\right)} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification67.9%

    \[\leadsto \begin{array}{l} \mathbf{if}\;e^{a} \leq 2 \cdot 10^{-8}:\\ \;\;\;\;\frac{b}{e^{a} + 1}\\ \mathbf{else}:\\ \;\;\;\;\log \left(b + \left(a + 2\right)\right)\\ \end{array} \]

Alternative 8: 96.1% accurate, 1.5× speedup?

\[\begin{array}{l} [a, b] = \mathsf{sort}([a, b])\\ \\ \mathsf{log1p}\left(e^{a} + b\right) \end{array} \]
NOTE: a and b should be sorted in increasing order before calling this function.
(FPCore (a b) :precision binary64 (log1p (+ (exp a) b)))
assert(a < b);
double code(double a, double b) {
	return log1p((exp(a) + b));
}
assert a < b;
public static double code(double a, double b) {
	return Math.log1p((Math.exp(a) + b));
}
[a, b] = sort([a, b])
def code(a, b):
	return math.log1p((math.exp(a) + b))
a, b = sort([a, b])
function code(a, b)
	return log1p(Float64(exp(a) + b))
end
NOTE: a and b should be sorted in increasing order before calling this function.
code[a_, b_] := N[Log[1 + N[(N[Exp[a], $MachinePrecision] + b), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}
[a, b] = \mathsf{sort}([a, b])\\
\\
\mathsf{log1p}\left(e^{a} + b\right)
\end{array}
Derivation
  1. Initial program 49.7%

    \[\log \left(e^{a} + e^{b}\right) \]
  2. Taylor expanded in b around 0 46.3%

    \[\leadsto \log \color{blue}{\left(1 + \left(e^{a} + b\right)\right)} \]
  3. Step-by-step derivation
    1. associate-+r+46.3%

      \[\leadsto \log \color{blue}{\left(\left(1 + e^{a}\right) + b\right)} \]
    2. +-commutative46.3%

      \[\leadsto \log \left(\color{blue}{\left(e^{a} + 1\right)} + b\right) \]
    3. associate-+l+46.3%

      \[\leadsto \log \color{blue}{\left(e^{a} + \left(1 + b\right)\right)} \]
  4. Simplified46.3%

    \[\leadsto \log \color{blue}{\left(e^{a} + \left(1 + b\right)\right)} \]
  5. Taylor expanded in a around inf 46.3%

    \[\leadsto \color{blue}{\log \left(1 + \left(e^{a} + b\right)\right)} \]
  6. Step-by-step derivation
    1. log1p-def68.5%

      \[\leadsto \color{blue}{\mathsf{log1p}\left(e^{a} + b\right)} \]
    2. +-commutative68.5%

      \[\leadsto \mathsf{log1p}\left(\color{blue}{b + e^{a}}\right) \]
  7. Simplified68.5%

    \[\leadsto \color{blue}{\mathsf{log1p}\left(b + e^{a}\right)} \]
  8. Final simplification68.5%

    \[\leadsto \mathsf{log1p}\left(e^{a} + b\right) \]

Alternative 9: 48.9% accurate, 2.9× speedup?

\[\begin{array}{l} [a, b] = \mathsf{sort}([a, b])\\ \\ b \cdot 0.5 + \log 2 \end{array} \]
NOTE: a and b should be sorted in increasing order before calling this function.
(FPCore (a b) :precision binary64 (+ (* b 0.5) (log 2.0)))
assert(a < b);
double code(double a, double b) {
	return (b * 0.5) + log(2.0);
}
NOTE: a and b should be sorted in increasing order before calling this function.
real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = (b * 0.5d0) + log(2.0d0)
end function
assert a < b;
public static double code(double a, double b) {
	return (b * 0.5) + Math.log(2.0);
}
[a, b] = sort([a, b])
def code(a, b):
	return (b * 0.5) + math.log(2.0)
a, b = sort([a, b])
function code(a, b)
	return Float64(Float64(b * 0.5) + log(2.0))
end
a, b = num2cell(sort([a, b])){:}
function tmp = code(a, b)
	tmp = (b * 0.5) + log(2.0);
end
NOTE: a and b should be sorted in increasing order before calling this function.
code[a_, b_] := N[(N[(b * 0.5), $MachinePrecision] + N[Log[2.0], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
[a, b] = \mathsf{sort}([a, b])\\
\\
b \cdot 0.5 + \log 2
\end{array}
Derivation
  1. Initial program 49.7%

    \[\log \left(e^{a} + e^{b}\right) \]
  2. Taylor expanded in b around 0 47.4%

    \[\leadsto \log \color{blue}{\left(1 + \left(e^{a} + \left(b + 0.5 \cdot {b}^{2}\right)\right)\right)} \]
  3. Step-by-step derivation
    1. +-commutative47.4%

      \[\leadsto \log \color{blue}{\left(\left(e^{a} + \left(b + 0.5 \cdot {b}^{2}\right)\right) + 1\right)} \]
    2. associate-+r+47.4%

      \[\leadsto \log \left(\color{blue}{\left(\left(e^{a} + b\right) + 0.5 \cdot {b}^{2}\right)} + 1\right) \]
    3. associate-+l+47.4%

      \[\leadsto \log \color{blue}{\left(\left(e^{a} + b\right) + \left(0.5 \cdot {b}^{2} + 1\right)\right)} \]
    4. +-commutative47.4%

      \[\leadsto \log \left(\color{blue}{\left(b + e^{a}\right)} + \left(0.5 \cdot {b}^{2} + 1\right)\right) \]
    5. associate-+l+47.4%

      \[\leadsto \log \color{blue}{\left(b + \left(e^{a} + \left(0.5 \cdot {b}^{2} + 1\right)\right)\right)} \]
    6. fma-def47.4%

      \[\leadsto \log \left(b + \left(e^{a} + \color{blue}{\mathsf{fma}\left(0.5, {b}^{2}, 1\right)}\right)\right) \]
    7. unpow247.4%

      \[\leadsto \log \left(b + \left(e^{a} + \mathsf{fma}\left(0.5, \color{blue}{b \cdot b}, 1\right)\right)\right) \]
  4. Simplified47.4%

    \[\leadsto \log \color{blue}{\left(b + \left(e^{a} + \mathsf{fma}\left(0.5, b \cdot b, 1\right)\right)\right)} \]
  5. Taylor expanded in a around 0 44.6%

    \[\leadsto \log \left(b + \color{blue}{\left(2 + 0.5 \cdot {b}^{2}\right)}\right) \]
  6. Step-by-step derivation
    1. unpow244.6%

      \[\leadsto \log \left(b + \left(2 + 0.5 \cdot \color{blue}{\left(b \cdot b\right)}\right)\right) \]
  7. Simplified44.6%

    \[\leadsto \log \left(b + \color{blue}{\left(2 + 0.5 \cdot \left(b \cdot b\right)\right)}\right) \]
  8. Taylor expanded in b around 0 44.4%

    \[\leadsto \color{blue}{0.5 \cdot b + \log 2} \]
  9. Final simplification44.4%

    \[\leadsto b \cdot 0.5 + \log 2 \]

Alternative 10: 48.6% accurate, 2.9× speedup?

\[\begin{array}{l} [a, b] = \mathsf{sort}([a, b])\\ \\ \log \left(b + 2\right) \end{array} \]
NOTE: a and b should be sorted in increasing order before calling this function.
(FPCore (a b) :precision binary64 (log (+ b 2.0)))
assert(a < b);
double code(double a, double b) {
	return log((b + 2.0));
}
NOTE: a and b should be sorted in increasing order before calling this function.
real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = log((b + 2.0d0))
end function
assert a < b;
public static double code(double a, double b) {
	return Math.log((b + 2.0));
}
[a, b] = sort([a, b])
def code(a, b):
	return math.log((b + 2.0))
a, b = sort([a, b])
function code(a, b)
	return log(Float64(b + 2.0))
end
a, b = num2cell(sort([a, b])){:}
function tmp = code(a, b)
	tmp = log((b + 2.0));
end
NOTE: a and b should be sorted in increasing order before calling this function.
code[a_, b_] := N[Log[N[(b + 2.0), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}
[a, b] = \mathsf{sort}([a, b])\\
\\
\log \left(b + 2\right)
\end{array}
Derivation
  1. Initial program 49.7%

    \[\log \left(e^{a} + e^{b}\right) \]
  2. Taylor expanded in b around 0 46.3%

    \[\leadsto \log \color{blue}{\left(1 + \left(e^{a} + b\right)\right)} \]
  3. Step-by-step derivation
    1. associate-+r+46.3%

      \[\leadsto \log \color{blue}{\left(\left(1 + e^{a}\right) + b\right)} \]
    2. +-commutative46.3%

      \[\leadsto \log \left(\color{blue}{\left(e^{a} + 1\right)} + b\right) \]
    3. associate-+l+46.3%

      \[\leadsto \log \color{blue}{\left(e^{a} + \left(1 + b\right)\right)} \]
  4. Simplified46.3%

    \[\leadsto \log \color{blue}{\left(e^{a} + \left(1 + b\right)\right)} \]
  5. Taylor expanded in a around 0 43.5%

    \[\leadsto \color{blue}{\log \left(2 + b\right)} \]
  6. Step-by-step derivation
    1. +-commutative43.5%

      \[\leadsto \log \color{blue}{\left(b + 2\right)} \]
  7. Simplified43.5%

    \[\leadsto \color{blue}{\log \left(b + 2\right)} \]
  8. Final simplification43.5%

    \[\leadsto \log \left(b + 2\right) \]

Alternative 11: 48.1% accurate, 3.0× speedup?

\[\begin{array}{l} [a, b] = \mathsf{sort}([a, b])\\ \\ \log 2 \end{array} \]
NOTE: a and b should be sorted in increasing order before calling this function.
(FPCore (a b) :precision binary64 (log 2.0))
assert(a < b);
double code(double a, double b) {
	return log(2.0);
}
NOTE: a and b should be sorted in increasing order before calling this function.
real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = log(2.0d0)
end function
assert a < b;
public static double code(double a, double b) {
	return Math.log(2.0);
}
[a, b] = sort([a, b])
def code(a, b):
	return math.log(2.0)
a, b = sort([a, b])
function code(a, b)
	return log(2.0)
end
a, b = num2cell(sort([a, b])){:}
function tmp = code(a, b)
	tmp = log(2.0);
end
NOTE: a and b should be sorted in increasing order before calling this function.
code[a_, b_] := N[Log[2.0], $MachinePrecision]
\begin{array}{l}
[a, b] = \mathsf{sort}([a, b])\\
\\
\log 2
\end{array}
Derivation
  1. Initial program 49.7%

    \[\log \left(e^{a} + e^{b}\right) \]
  2. Taylor expanded in b around 0 47.4%

    \[\leadsto \log \color{blue}{\left(1 + \left(e^{a} + \left(b + 0.5 \cdot {b}^{2}\right)\right)\right)} \]
  3. Step-by-step derivation
    1. +-commutative47.4%

      \[\leadsto \log \color{blue}{\left(\left(e^{a} + \left(b + 0.5 \cdot {b}^{2}\right)\right) + 1\right)} \]
    2. associate-+r+47.4%

      \[\leadsto \log \left(\color{blue}{\left(\left(e^{a} + b\right) + 0.5 \cdot {b}^{2}\right)} + 1\right) \]
    3. associate-+l+47.4%

      \[\leadsto \log \color{blue}{\left(\left(e^{a} + b\right) + \left(0.5 \cdot {b}^{2} + 1\right)\right)} \]
    4. +-commutative47.4%

      \[\leadsto \log \left(\color{blue}{\left(b + e^{a}\right)} + \left(0.5 \cdot {b}^{2} + 1\right)\right) \]
    5. associate-+l+47.4%

      \[\leadsto \log \color{blue}{\left(b + \left(e^{a} + \left(0.5 \cdot {b}^{2} + 1\right)\right)\right)} \]
    6. fma-def47.4%

      \[\leadsto \log \left(b + \left(e^{a} + \color{blue}{\mathsf{fma}\left(0.5, {b}^{2}, 1\right)}\right)\right) \]
    7. unpow247.4%

      \[\leadsto \log \left(b + \left(e^{a} + \mathsf{fma}\left(0.5, \color{blue}{b \cdot b}, 1\right)\right)\right) \]
  4. Simplified47.4%

    \[\leadsto \log \color{blue}{\left(b + \left(e^{a} + \mathsf{fma}\left(0.5, b \cdot b, 1\right)\right)\right)} \]
  5. Taylor expanded in a around 0 44.6%

    \[\leadsto \log \left(b + \color{blue}{\left(2 + 0.5 \cdot {b}^{2}\right)}\right) \]
  6. Step-by-step derivation
    1. unpow244.6%

      \[\leadsto \log \left(b + \left(2 + 0.5 \cdot \color{blue}{\left(b \cdot b\right)}\right)\right) \]
  7. Simplified44.6%

    \[\leadsto \log \left(b + \color{blue}{\left(2 + 0.5 \cdot \left(b \cdot b\right)\right)}\right) \]
  8. Taylor expanded in b around 0 44.4%

    \[\leadsto \color{blue}{\log 2} \]
  9. Final simplification44.4%

    \[\leadsto \log 2 \]

Alternative 12: 2.6% accurate, 60.6× speedup?

\[\begin{array}{l} [a, b] = \mathsf{sort}([a, b])\\ \\ \frac{a}{b + 2} \end{array} \]
NOTE: a and b should be sorted in increasing order before calling this function.
(FPCore (a b) :precision binary64 (/ a (+ b 2.0)))
assert(a < b);
double code(double a, double b) {
	return a / (b + 2.0);
}
NOTE: a and b should be sorted in increasing order before calling this function.
real(8) function code(a, b)
    real(8), intent (in) :: a
    real(8), intent (in) :: b
    code = a / (b + 2.0d0)
end function
assert a < b;
public static double code(double a, double b) {
	return a / (b + 2.0);
}
[a, b] = sort([a, b])
def code(a, b):
	return a / (b + 2.0)
a, b = sort([a, b])
function code(a, b)
	return Float64(a / Float64(b + 2.0))
end
a, b = num2cell(sort([a, b])){:}
function tmp = code(a, b)
	tmp = a / (b + 2.0);
end
NOTE: a and b should be sorted in increasing order before calling this function.
code[a_, b_] := N[(a / N[(b + 2.0), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
[a, b] = \mathsf{sort}([a, b])\\
\\
\frac{a}{b + 2}
\end{array}
Derivation
  1. Initial program 49.7%

    \[\log \left(e^{a} + e^{b}\right) \]
  2. Taylor expanded in b around 0 46.3%

    \[\leadsto \log \color{blue}{\left(1 + \left(e^{a} + b\right)\right)} \]
  3. Step-by-step derivation
    1. associate-+r+46.3%

      \[\leadsto \log \color{blue}{\left(\left(1 + e^{a}\right) + b\right)} \]
    2. +-commutative46.3%

      \[\leadsto \log \left(\color{blue}{\left(e^{a} + 1\right)} + b\right) \]
    3. associate-+l+46.3%

      \[\leadsto \log \color{blue}{\left(e^{a} + \left(1 + b\right)\right)} \]
  4. Simplified46.3%

    \[\leadsto \log \color{blue}{\left(e^{a} + \left(1 + b\right)\right)} \]
  5. Taylor expanded in a around 0 43.9%

    \[\leadsto \color{blue}{\frac{a}{2 + b} + \log \left(2 + b\right)} \]
  6. Taylor expanded in a around inf 3.9%

    \[\leadsto \color{blue}{\frac{a}{2 + b}} \]
  7. Step-by-step derivation
    1. +-commutative3.9%

      \[\leadsto \frac{a}{\color{blue}{b + 2}} \]
  8. Simplified3.9%

    \[\leadsto \color{blue}{\frac{a}{b + 2}} \]
  9. Final simplification3.9%

    \[\leadsto \frac{a}{b + 2} \]

Reproduce

?
herbie shell --seed 2023174 
(FPCore (a b)
  :name "symmetry log of sum of exp"
  :precision binary64
  (log (+ (exp a) (exp b))))