Toniolo and Linder, Equation (3a)

Percentage Accurate: 98.4% → 100.0%
Time: 12.3s
Alternatives: 6
Speedup: 0.9×

Specification

?
\[\begin{array}{l} \\ \sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}}\right)} \end{array} \]
(FPCore (l Om kx ky)
 :precision binary64
 (sqrt
  (*
   (/ 1.0 2.0)
   (+
    1.0
    (/
     1.0
     (sqrt
      (+
       1.0
       (*
        (pow (/ (* 2.0 l) Om) 2.0)
        (+ (pow (sin kx) 2.0) (pow (sin ky) 2.0))))))))))
double code(double l, double Om, double kx, double ky) {
	return sqrt(((1.0 / 2.0) * (1.0 + (1.0 / sqrt((1.0 + (pow(((2.0 * l) / Om), 2.0) * (pow(sin(kx), 2.0) + pow(sin(ky), 2.0)))))))));
}
real(8) function code(l, om, kx, ky)
    real(8), intent (in) :: l
    real(8), intent (in) :: om
    real(8), intent (in) :: kx
    real(8), intent (in) :: ky
    code = sqrt(((1.0d0 / 2.0d0) * (1.0d0 + (1.0d0 / sqrt((1.0d0 + ((((2.0d0 * l) / om) ** 2.0d0) * ((sin(kx) ** 2.0d0) + (sin(ky) ** 2.0d0)))))))))
end function
public static double code(double l, double Om, double kx, double ky) {
	return Math.sqrt(((1.0 / 2.0) * (1.0 + (1.0 / Math.sqrt((1.0 + (Math.pow(((2.0 * l) / Om), 2.0) * (Math.pow(Math.sin(kx), 2.0) + Math.pow(Math.sin(ky), 2.0)))))))));
}
def code(l, Om, kx, ky):
	return math.sqrt(((1.0 / 2.0) * (1.0 + (1.0 / math.sqrt((1.0 + (math.pow(((2.0 * l) / Om), 2.0) * (math.pow(math.sin(kx), 2.0) + math.pow(math.sin(ky), 2.0)))))))))
function code(l, Om, kx, ky)
	return sqrt(Float64(Float64(1.0 / 2.0) * Float64(1.0 + Float64(1.0 / sqrt(Float64(1.0 + Float64((Float64(Float64(2.0 * l) / Om) ^ 2.0) * Float64((sin(kx) ^ 2.0) + (sin(ky) ^ 2.0)))))))))
end
function tmp = code(l, Om, kx, ky)
	tmp = sqrt(((1.0 / 2.0) * (1.0 + (1.0 / sqrt((1.0 + ((((2.0 * l) / Om) ^ 2.0) * ((sin(kx) ^ 2.0) + (sin(ky) ^ 2.0)))))))));
end
code[l_, Om_, kx_, ky_] := N[Sqrt[N[(N[(1.0 / 2.0), $MachinePrecision] * N[(1.0 + N[(1.0 / N[Sqrt[N[(1.0 + N[(N[Power[N[(N[(2.0 * l), $MachinePrecision] / Om), $MachinePrecision], 2.0], $MachinePrecision] * N[(N[Power[N[Sin[kx], $MachinePrecision], 2.0], $MachinePrecision] + N[Power[N[Sin[ky], $MachinePrecision], 2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}}\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 6 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: 98.4% accurate, 1.0× speedup?

\[\begin{array}{l} \\ \sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}}\right)} \end{array} \]
(FPCore (l Om kx ky)
 :precision binary64
 (sqrt
  (*
   (/ 1.0 2.0)
   (+
    1.0
    (/
     1.0
     (sqrt
      (+
       1.0
       (*
        (pow (/ (* 2.0 l) Om) 2.0)
        (+ (pow (sin kx) 2.0) (pow (sin ky) 2.0))))))))))
double code(double l, double Om, double kx, double ky) {
	return sqrt(((1.0 / 2.0) * (1.0 + (1.0 / sqrt((1.0 + (pow(((2.0 * l) / Om), 2.0) * (pow(sin(kx), 2.0) + pow(sin(ky), 2.0)))))))));
}
real(8) function code(l, om, kx, ky)
    real(8), intent (in) :: l
    real(8), intent (in) :: om
    real(8), intent (in) :: kx
    real(8), intent (in) :: ky
    code = sqrt(((1.0d0 / 2.0d0) * (1.0d0 + (1.0d0 / sqrt((1.0d0 + ((((2.0d0 * l) / om) ** 2.0d0) * ((sin(kx) ** 2.0d0) + (sin(ky) ** 2.0d0)))))))))
end function
public static double code(double l, double Om, double kx, double ky) {
	return Math.sqrt(((1.0 / 2.0) * (1.0 + (1.0 / Math.sqrt((1.0 + (Math.pow(((2.0 * l) / Om), 2.0) * (Math.pow(Math.sin(kx), 2.0) + Math.pow(Math.sin(ky), 2.0)))))))));
}
def code(l, Om, kx, ky):
	return math.sqrt(((1.0 / 2.0) * (1.0 + (1.0 / math.sqrt((1.0 + (math.pow(((2.0 * l) / Om), 2.0) * (math.pow(math.sin(kx), 2.0) + math.pow(math.sin(ky), 2.0)))))))))
function code(l, Om, kx, ky)
	return sqrt(Float64(Float64(1.0 / 2.0) * Float64(1.0 + Float64(1.0 / sqrt(Float64(1.0 + Float64((Float64(Float64(2.0 * l) / Om) ^ 2.0) * Float64((sin(kx) ^ 2.0) + (sin(ky) ^ 2.0)))))))))
end
function tmp = code(l, Om, kx, ky)
	tmp = sqrt(((1.0 / 2.0) * (1.0 + (1.0 / sqrt((1.0 + ((((2.0 * l) / Om) ^ 2.0) * ((sin(kx) ^ 2.0) + (sin(ky) ^ 2.0)))))))));
end
code[l_, Om_, kx_, ky_] := N[Sqrt[N[(N[(1.0 / 2.0), $MachinePrecision] * N[(1.0 + N[(1.0 / N[Sqrt[N[(1.0 + N[(N[Power[N[(N[(2.0 * l), $MachinePrecision] / Om), $MachinePrecision], 2.0], $MachinePrecision] * N[(N[Power[N[Sin[kx], $MachinePrecision], 2.0], $MachinePrecision] + N[Power[N[Sin[ky], $MachinePrecision], 2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}}\right)}
\end{array}

Alternative 1: 100.0% accurate, 0.9× speedup?

\[\begin{array}{l} \\ \sqrt{{2}^{-1} \cdot \left(1 + {\left(\sqrt{{\left(\frac{\ell}{Om} \cdot \left(2 \cdot \sin ky\right)\right)}^{2} + \left({\left(\left(\sin kx \cdot \ell\right) \cdot \frac{2}{Om}\right)}^{2} + 1\right)}\right)}^{-1}\right)} \end{array} \]
(FPCore (l Om kx ky)
 :precision binary64
 (sqrt
  (*
   (pow 2.0 -1.0)
   (+
    1.0
    (pow
     (sqrt
      (+
       (pow (* (/ l Om) (* 2.0 (sin ky))) 2.0)
       (+ (pow (* (* (sin kx) l) (/ 2.0 Om)) 2.0) 1.0)))
     -1.0)))))
double code(double l, double Om, double kx, double ky) {
	return sqrt((pow(2.0, -1.0) * (1.0 + pow(sqrt((pow(((l / Om) * (2.0 * sin(ky))), 2.0) + (pow(((sin(kx) * l) * (2.0 / Om)), 2.0) + 1.0))), -1.0))));
}
real(8) function code(l, om, kx, ky)
    real(8), intent (in) :: l
    real(8), intent (in) :: om
    real(8), intent (in) :: kx
    real(8), intent (in) :: ky
    code = sqrt(((2.0d0 ** (-1.0d0)) * (1.0d0 + (sqrt(((((l / om) * (2.0d0 * sin(ky))) ** 2.0d0) + ((((sin(kx) * l) * (2.0d0 / om)) ** 2.0d0) + 1.0d0))) ** (-1.0d0)))))
end function
public static double code(double l, double Om, double kx, double ky) {
	return Math.sqrt((Math.pow(2.0, -1.0) * (1.0 + Math.pow(Math.sqrt((Math.pow(((l / Om) * (2.0 * Math.sin(ky))), 2.0) + (Math.pow(((Math.sin(kx) * l) * (2.0 / Om)), 2.0) + 1.0))), -1.0))));
}
def code(l, Om, kx, ky):
	return math.sqrt((math.pow(2.0, -1.0) * (1.0 + math.pow(math.sqrt((math.pow(((l / Om) * (2.0 * math.sin(ky))), 2.0) + (math.pow(((math.sin(kx) * l) * (2.0 / Om)), 2.0) + 1.0))), -1.0))))
function code(l, Om, kx, ky)
	return sqrt(Float64((2.0 ^ -1.0) * Float64(1.0 + (sqrt(Float64((Float64(Float64(l / Om) * Float64(2.0 * sin(ky))) ^ 2.0) + Float64((Float64(Float64(sin(kx) * l) * Float64(2.0 / Om)) ^ 2.0) + 1.0))) ^ -1.0))))
end
function tmp = code(l, Om, kx, ky)
	tmp = sqrt(((2.0 ^ -1.0) * (1.0 + (sqrt(((((l / Om) * (2.0 * sin(ky))) ^ 2.0) + ((((sin(kx) * l) * (2.0 / Om)) ^ 2.0) + 1.0))) ^ -1.0))));
end
code[l_, Om_, kx_, ky_] := N[Sqrt[N[(N[Power[2.0, -1.0], $MachinePrecision] * N[(1.0 + N[Power[N[Sqrt[N[(N[Power[N[(N[(l / Om), $MachinePrecision] * N[(2.0 * N[Sin[ky], $MachinePrecision]), $MachinePrecision]), $MachinePrecision], 2.0], $MachinePrecision] + N[(N[Power[N[(N[(N[Sin[kx], $MachinePrecision] * l), $MachinePrecision] * N[(2.0 / Om), $MachinePrecision]), $MachinePrecision], 2.0], $MachinePrecision] + 1.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision], -1.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]
\begin{array}{l}

\\
\sqrt{{2}^{-1} \cdot \left(1 + {\left(\sqrt{{\left(\frac{\ell}{Om} \cdot \left(2 \cdot \sin ky\right)\right)}^{2} + \left({\left(\left(\sin kx \cdot \ell\right) \cdot \frac{2}{Om}\right)}^{2} + 1\right)}\right)}^{-1}\right)}
\end{array}
Derivation
  1. Initial program 98.6%

    \[\sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}}\right)} \]
  2. Add Preprocessing
  3. Step-by-step derivation
    1. lift-+.f64N/A

      \[\leadsto \sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{\color{blue}{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}}}\right)} \]
    2. +-commutativeN/A

      \[\leadsto \sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{\color{blue}{{\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right) + 1}}}\right)} \]
    3. lift-*.f64N/A

      \[\leadsto \sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{\color{blue}{{\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)} + 1}}\right)} \]
    4. lift-+.f64N/A

      \[\leadsto \sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{{\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \color{blue}{\left({\sin kx}^{2} + {\sin ky}^{2}\right)} + 1}}\right)} \]
    5. +-commutativeN/A

      \[\leadsto \sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{{\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \color{blue}{\left({\sin ky}^{2} + {\sin kx}^{2}\right)} + 1}}\right)} \]
    6. distribute-lft-inN/A

      \[\leadsto \sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{\color{blue}{\left({\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot {\sin ky}^{2} + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot {\sin kx}^{2}\right)} + 1}}\right)} \]
    7. *-commutativeN/A

      \[\leadsto \sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{\left(\color{blue}{{\sin ky}^{2} \cdot {\left(\frac{2 \cdot \ell}{Om}\right)}^{2}} + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot {\sin kx}^{2}\right) + 1}}\right)} \]
    8. associate-+l+N/A

      \[\leadsto \sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{\color{blue}{{\sin ky}^{2} \cdot {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} + \left({\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot {\sin kx}^{2} + 1\right)}}}\right)} \]
    9. lower-+.f64N/A

      \[\leadsto \sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{\color{blue}{{\sin ky}^{2} \cdot {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} + \left({\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot {\sin kx}^{2} + 1\right)}}}\right)} \]
  4. Applied rewrites100.0%

    \[\leadsto \sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{\color{blue}{{\left(\frac{\ell}{Om} \cdot \left(2 \cdot \sin ky\right)\right)}^{2} + \left({\left(\left(\sin kx \cdot \ell\right) \cdot \frac{2}{Om}\right)}^{2} + 1\right)}}}\right)} \]
  5. Final simplification100.0%

    \[\leadsto \sqrt{{2}^{-1} \cdot \left(1 + {\left(\sqrt{{\left(\frac{\ell}{Om} \cdot \left(2 \cdot \sin ky\right)\right)}^{2} + \left({\left(\left(\sin kx \cdot \ell\right) \cdot \frac{2}{Om}\right)}^{2} + 1\right)}\right)}^{-1}\right)} \]
  6. Add Preprocessing

Alternative 2: 91.7% accurate, 0.7× speedup?

\[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;{\left(\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}\right)}^{-1} \leq 0.5:\\ \;\;\;\;\sqrt{\mathsf{fma}\left(\frac{Om}{\sin ky \cdot \ell}, 0.25, 0.5\right)}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{1}\\ \end{array} \end{array} \]
(FPCore (l Om kx ky)
 :precision binary64
 (if (<=
      (pow
       (sqrt
        (+
         1.0
         (*
          (pow (/ (* 2.0 l) Om) 2.0)
          (+ (pow (sin kx) 2.0) (pow (sin ky) 2.0)))))
       -1.0)
      0.5)
   (sqrt (fma (/ Om (* (sin ky) l)) 0.25 0.5))
   (sqrt 1.0)))
double code(double l, double Om, double kx, double ky) {
	double tmp;
	if (pow(sqrt((1.0 + (pow(((2.0 * l) / Om), 2.0) * (pow(sin(kx), 2.0) + pow(sin(ky), 2.0))))), -1.0) <= 0.5) {
		tmp = sqrt(fma((Om / (sin(ky) * l)), 0.25, 0.5));
	} else {
		tmp = sqrt(1.0);
	}
	return tmp;
}
function code(l, Om, kx, ky)
	tmp = 0.0
	if ((sqrt(Float64(1.0 + Float64((Float64(Float64(2.0 * l) / Om) ^ 2.0) * Float64((sin(kx) ^ 2.0) + (sin(ky) ^ 2.0))))) ^ -1.0) <= 0.5)
		tmp = sqrt(fma(Float64(Om / Float64(sin(ky) * l)), 0.25, 0.5));
	else
		tmp = sqrt(1.0);
	end
	return tmp
end
code[l_, Om_, kx_, ky_] := If[LessEqual[N[Power[N[Sqrt[N[(1.0 + N[(N[Power[N[(N[(2.0 * l), $MachinePrecision] / Om), $MachinePrecision], 2.0], $MachinePrecision] * N[(N[Power[N[Sin[kx], $MachinePrecision], 2.0], $MachinePrecision] + N[Power[N[Sin[ky], $MachinePrecision], 2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision], -1.0], $MachinePrecision], 0.5], N[Sqrt[N[(N[(Om / N[(N[Sin[ky], $MachinePrecision] * l), $MachinePrecision]), $MachinePrecision] * 0.25 + 0.5), $MachinePrecision]], $MachinePrecision], N[Sqrt[1.0], $MachinePrecision]]
\begin{array}{l}

\\
\begin{array}{l}
\mathbf{if}\;{\left(\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}\right)}^{-1} \leq 0.5:\\
\;\;\;\;\sqrt{\mathsf{fma}\left(\frac{Om}{\sin ky \cdot \ell}, 0.25, 0.5\right)}\\

\mathbf{else}:\\
\;\;\;\;\sqrt{1}\\


\end{array}
\end{array}
Derivation
  1. Split input into 2 regimes
  2. if (/.f64 #s(literal 1 binary64) (sqrt.f64 (+.f64 #s(literal 1 binary64) (*.f64 (pow.f64 (/.f64 (*.f64 #s(literal 2 binary64) l) Om) #s(literal 2 binary64)) (+.f64 (pow.f64 (sin.f64 kx) #s(literal 2 binary64)) (pow.f64 (sin.f64 ky) #s(literal 2 binary64))))))) < 0.5

    1. Initial program 99.5%

      \[\sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}}\right)} \]
    2. Add Preprocessing
    3. Taylor expanded in kx around 0

      \[\leadsto \sqrt{\color{blue}{\frac{1}{2} \cdot \left(1 + \sqrt{\frac{1}{1 + 4 \cdot \frac{{\ell}^{2} \cdot {\sin ky}^{2}}{{Om}^{2}}}}\right)}} \]
    4. Step-by-step derivation
      1. +-commutativeN/A

        \[\leadsto \sqrt{\frac{1}{2} \cdot \color{blue}{\left(\sqrt{\frac{1}{1 + 4 \cdot \frac{{\ell}^{2} \cdot {\sin ky}^{2}}{{Om}^{2}}}} + 1\right)}} \]
      2. distribute-rgt-inN/A

        \[\leadsto \sqrt{\color{blue}{\sqrt{\frac{1}{1 + 4 \cdot \frac{{\ell}^{2} \cdot {\sin ky}^{2}}{{Om}^{2}}}} \cdot \frac{1}{2} + 1 \cdot \frac{1}{2}}} \]
      3. metadata-evalN/A

        \[\leadsto \sqrt{\sqrt{\frac{1}{1 + 4 \cdot \frac{{\ell}^{2} \cdot {\sin ky}^{2}}{{Om}^{2}}}} \cdot \frac{1}{2} + \color{blue}{\frac{1}{2}}} \]
      4. lower-fma.f64N/A

        \[\leadsto \sqrt{\color{blue}{\mathsf{fma}\left(\sqrt{\frac{1}{1 + 4 \cdot \frac{{\ell}^{2} \cdot {\sin ky}^{2}}{{Om}^{2}}}}, \frac{1}{2}, \frac{1}{2}\right)}} \]
    5. Applied rewrites71.9%

      \[\leadsto \sqrt{\color{blue}{\mathsf{fma}\left(\sqrt{\frac{1}{\mathsf{fma}\left(\frac{{\sin ky}^{2}}{Om} \cdot \frac{\ell \cdot \ell}{Om}, 4, 1\right)}}, 0.5, 0.5\right)}} \]
    6. Taylor expanded in l around inf

      \[\leadsto \sqrt{\frac{1}{2} + \color{blue}{\frac{1}{4} \cdot \frac{Om}{\ell \cdot \sin ky}}} \]
    7. Step-by-step derivation
      1. Applied rewrites84.7%

        \[\leadsto \sqrt{\mathsf{fma}\left(\frac{Om}{\sin ky \cdot \ell}, \color{blue}{0.25}, 0.5\right)} \]

      if 0.5 < (/.f64 #s(literal 1 binary64) (sqrt.f64 (+.f64 #s(literal 1 binary64) (*.f64 (pow.f64 (/.f64 (*.f64 #s(literal 2 binary64) l) Om) #s(literal 2 binary64)) (+.f64 (pow.f64 (sin.f64 kx) #s(literal 2 binary64)) (pow.f64 (sin.f64 ky) #s(literal 2 binary64)))))))

      1. Initial program 97.9%

        \[\sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}}\right)} \]
      2. Add Preprocessing
      3. Taylor expanded in l around 0

        \[\leadsto \sqrt{\color{blue}{1}} \]
      4. Step-by-step derivation
        1. Applied rewrites99.1%

          \[\leadsto \sqrt{\color{blue}{1}} \]
      5. Recombined 2 regimes into one program.
      6. Final simplification92.7%

        \[\leadsto \begin{array}{l} \mathbf{if}\;{\left(\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}\right)}^{-1} \leq 0.5:\\ \;\;\;\;\sqrt{\mathsf{fma}\left(\frac{Om}{\sin ky \cdot \ell}, 0.25, 0.5\right)}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{1}\\ \end{array} \]
      7. Add Preprocessing

      Alternative 3: 91.6% accurate, 0.9× speedup?

      \[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;{\left(\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}\right)}^{-1} \leq 0.5:\\ \;\;\;\;\sqrt{\mathsf{fma}\left(0.25, \frac{Om}{ky \cdot \ell}, 0.5\right)}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{1}\\ \end{array} \end{array} \]
      (FPCore (l Om kx ky)
       :precision binary64
       (if (<=
            (pow
             (sqrt
              (+
               1.0
               (*
                (pow (/ (* 2.0 l) Om) 2.0)
                (+ (pow (sin kx) 2.0) (pow (sin ky) 2.0)))))
             -1.0)
            0.5)
         (sqrt (fma 0.25 (/ Om (* ky l)) 0.5))
         (sqrt 1.0)))
      double code(double l, double Om, double kx, double ky) {
      	double tmp;
      	if (pow(sqrt((1.0 + (pow(((2.0 * l) / Om), 2.0) * (pow(sin(kx), 2.0) + pow(sin(ky), 2.0))))), -1.0) <= 0.5) {
      		tmp = sqrt(fma(0.25, (Om / (ky * l)), 0.5));
      	} else {
      		tmp = sqrt(1.0);
      	}
      	return tmp;
      }
      
      function code(l, Om, kx, ky)
      	tmp = 0.0
      	if ((sqrt(Float64(1.0 + Float64((Float64(Float64(2.0 * l) / Om) ^ 2.0) * Float64((sin(kx) ^ 2.0) + (sin(ky) ^ 2.0))))) ^ -1.0) <= 0.5)
      		tmp = sqrt(fma(0.25, Float64(Om / Float64(ky * l)), 0.5));
      	else
      		tmp = sqrt(1.0);
      	end
      	return tmp
      end
      
      code[l_, Om_, kx_, ky_] := If[LessEqual[N[Power[N[Sqrt[N[(1.0 + N[(N[Power[N[(N[(2.0 * l), $MachinePrecision] / Om), $MachinePrecision], 2.0], $MachinePrecision] * N[(N[Power[N[Sin[kx], $MachinePrecision], 2.0], $MachinePrecision] + N[Power[N[Sin[ky], $MachinePrecision], 2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision], -1.0], $MachinePrecision], 0.5], N[Sqrt[N[(0.25 * N[(Om / N[(ky * l), $MachinePrecision]), $MachinePrecision] + 0.5), $MachinePrecision]], $MachinePrecision], N[Sqrt[1.0], $MachinePrecision]]
      
      \begin{array}{l}
      
      \\
      \begin{array}{l}
      \mathbf{if}\;{\left(\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}\right)}^{-1} \leq 0.5:\\
      \;\;\;\;\sqrt{\mathsf{fma}\left(0.25, \frac{Om}{ky \cdot \ell}, 0.5\right)}\\
      
      \mathbf{else}:\\
      \;\;\;\;\sqrt{1}\\
      
      
      \end{array}
      \end{array}
      
      Derivation
      1. Split input into 2 regimes
      2. if (/.f64 #s(literal 1 binary64) (sqrt.f64 (+.f64 #s(literal 1 binary64) (*.f64 (pow.f64 (/.f64 (*.f64 #s(literal 2 binary64) l) Om) #s(literal 2 binary64)) (+.f64 (pow.f64 (sin.f64 kx) #s(literal 2 binary64)) (pow.f64 (sin.f64 ky) #s(literal 2 binary64))))))) < 0.5

        1. Initial program 99.5%

          \[\sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}}\right)} \]
        2. Add Preprocessing
        3. Taylor expanded in kx around 0

          \[\leadsto \sqrt{\color{blue}{\frac{1}{2} \cdot \left(1 + \sqrt{\frac{1}{1 + 4 \cdot \frac{{\ell}^{2} \cdot {\sin ky}^{2}}{{Om}^{2}}}}\right)}} \]
        4. Step-by-step derivation
          1. +-commutativeN/A

            \[\leadsto \sqrt{\frac{1}{2} \cdot \color{blue}{\left(\sqrt{\frac{1}{1 + 4 \cdot \frac{{\ell}^{2} \cdot {\sin ky}^{2}}{{Om}^{2}}}} + 1\right)}} \]
          2. distribute-rgt-inN/A

            \[\leadsto \sqrt{\color{blue}{\sqrt{\frac{1}{1 + 4 \cdot \frac{{\ell}^{2} \cdot {\sin ky}^{2}}{{Om}^{2}}}} \cdot \frac{1}{2} + 1 \cdot \frac{1}{2}}} \]
          3. metadata-evalN/A

            \[\leadsto \sqrt{\sqrt{\frac{1}{1 + 4 \cdot \frac{{\ell}^{2} \cdot {\sin ky}^{2}}{{Om}^{2}}}} \cdot \frac{1}{2} + \color{blue}{\frac{1}{2}}} \]
          4. lower-fma.f64N/A

            \[\leadsto \sqrt{\color{blue}{\mathsf{fma}\left(\sqrt{\frac{1}{1 + 4 \cdot \frac{{\ell}^{2} \cdot {\sin ky}^{2}}{{Om}^{2}}}}, \frac{1}{2}, \frac{1}{2}\right)}} \]
        5. Applied rewrites71.9%

          \[\leadsto \sqrt{\color{blue}{\mathsf{fma}\left(\sqrt{\frac{1}{\mathsf{fma}\left(\frac{{\sin ky}^{2}}{Om} \cdot \frac{\ell \cdot \ell}{Om}, 4, 1\right)}}, 0.5, 0.5\right)}} \]
        6. Step-by-step derivation
          1. Applied rewrites74.7%

            \[\leadsto \sqrt{\mathsf{fma}\left(\sqrt{\frac{1}{\mathsf{fma}\left(\frac{{\sin ky}^{2}}{Om}, 4 \cdot \left(\frac{\ell}{Om} \cdot \ell\right), 1\right)}}, 0.5, 0.5\right)} \]
          2. Taylor expanded in l around inf

            \[\leadsto \sqrt{\frac{1}{2} + \color{blue}{\frac{1}{4} \cdot \frac{Om}{\ell \cdot \sin ky}}} \]
          3. Step-by-step derivation
            1. Applied rewrites84.7%

              \[\leadsto \sqrt{\mathsf{fma}\left(0.25, \color{blue}{\frac{Om}{\ell \cdot \sin ky}}, 0.5\right)} \]
            2. Taylor expanded in ky around 0

              \[\leadsto \sqrt{\mathsf{fma}\left(\frac{1}{4}, \frac{Om}{ky \cdot \ell}, \frac{1}{2}\right)} \]
            3. Step-by-step derivation
              1. Applied rewrites84.7%

                \[\leadsto \sqrt{\mathsf{fma}\left(0.25, \frac{Om}{ky \cdot \ell}, 0.5\right)} \]

              if 0.5 < (/.f64 #s(literal 1 binary64) (sqrt.f64 (+.f64 #s(literal 1 binary64) (*.f64 (pow.f64 (/.f64 (*.f64 #s(literal 2 binary64) l) Om) #s(literal 2 binary64)) (+.f64 (pow.f64 (sin.f64 kx) #s(literal 2 binary64)) (pow.f64 (sin.f64 ky) #s(literal 2 binary64)))))))

              1. Initial program 97.9%

                \[\sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}}\right)} \]
              2. Add Preprocessing
              3. Taylor expanded in l around 0

                \[\leadsto \sqrt{\color{blue}{1}} \]
              4. Step-by-step derivation
                1. Applied rewrites99.1%

                  \[\leadsto \sqrt{\color{blue}{1}} \]
              5. Recombined 2 regimes into one program.
              6. Final simplification92.7%

                \[\leadsto \begin{array}{l} \mathbf{if}\;{\left(\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}\right)}^{-1} \leq 0.5:\\ \;\;\;\;\sqrt{\mathsf{fma}\left(0.25, \frac{Om}{ky \cdot \ell}, 0.5\right)}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{1}\\ \end{array} \]
              7. Add Preprocessing

              Alternative 4: 97.5% accurate, 0.9× speedup?

              \[\begin{array}{l} \\ \begin{array}{l} \mathbf{if}\;{\left(\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}\right)}^{-1} \leq 0.46:\\ \;\;\;\;\sqrt{0.5}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{1}\\ \end{array} \end{array} \]
              (FPCore (l Om kx ky)
               :precision binary64
               (if (<=
                    (pow
                     (sqrt
                      (+
                       1.0
                       (*
                        (pow (/ (* 2.0 l) Om) 2.0)
                        (+ (pow (sin kx) 2.0) (pow (sin ky) 2.0)))))
                     -1.0)
                    0.46)
                 (sqrt 0.5)
                 (sqrt 1.0)))
              double code(double l, double Om, double kx, double ky) {
              	double tmp;
              	if (pow(sqrt((1.0 + (pow(((2.0 * l) / Om), 2.0) * (pow(sin(kx), 2.0) + pow(sin(ky), 2.0))))), -1.0) <= 0.46) {
              		tmp = sqrt(0.5);
              	} else {
              		tmp = sqrt(1.0);
              	}
              	return tmp;
              }
              
              real(8) function code(l, om, kx, ky)
                  real(8), intent (in) :: l
                  real(8), intent (in) :: om
                  real(8), intent (in) :: kx
                  real(8), intent (in) :: ky
                  real(8) :: tmp
                  if ((sqrt((1.0d0 + ((((2.0d0 * l) / om) ** 2.0d0) * ((sin(kx) ** 2.0d0) + (sin(ky) ** 2.0d0))))) ** (-1.0d0)) <= 0.46d0) then
                      tmp = sqrt(0.5d0)
                  else
                      tmp = sqrt(1.0d0)
                  end if
                  code = tmp
              end function
              
              public static double code(double l, double Om, double kx, double ky) {
              	double tmp;
              	if (Math.pow(Math.sqrt((1.0 + (Math.pow(((2.0 * l) / Om), 2.0) * (Math.pow(Math.sin(kx), 2.0) + Math.pow(Math.sin(ky), 2.0))))), -1.0) <= 0.46) {
              		tmp = Math.sqrt(0.5);
              	} else {
              		tmp = Math.sqrt(1.0);
              	}
              	return tmp;
              }
              
              def code(l, Om, kx, ky):
              	tmp = 0
              	if math.pow(math.sqrt((1.0 + (math.pow(((2.0 * l) / Om), 2.0) * (math.pow(math.sin(kx), 2.0) + math.pow(math.sin(ky), 2.0))))), -1.0) <= 0.46:
              		tmp = math.sqrt(0.5)
              	else:
              		tmp = math.sqrt(1.0)
              	return tmp
              
              function code(l, Om, kx, ky)
              	tmp = 0.0
              	if ((sqrt(Float64(1.0 + Float64((Float64(Float64(2.0 * l) / Om) ^ 2.0) * Float64((sin(kx) ^ 2.0) + (sin(ky) ^ 2.0))))) ^ -1.0) <= 0.46)
              		tmp = sqrt(0.5);
              	else
              		tmp = sqrt(1.0);
              	end
              	return tmp
              end
              
              function tmp_2 = code(l, Om, kx, ky)
              	tmp = 0.0;
              	if ((sqrt((1.0 + ((((2.0 * l) / Om) ^ 2.0) * ((sin(kx) ^ 2.0) + (sin(ky) ^ 2.0))))) ^ -1.0) <= 0.46)
              		tmp = sqrt(0.5);
              	else
              		tmp = sqrt(1.0);
              	end
              	tmp_2 = tmp;
              end
              
              code[l_, Om_, kx_, ky_] := If[LessEqual[N[Power[N[Sqrt[N[(1.0 + N[(N[Power[N[(N[(2.0 * l), $MachinePrecision] / Om), $MachinePrecision], 2.0], $MachinePrecision] * N[(N[Power[N[Sin[kx], $MachinePrecision], 2.0], $MachinePrecision] + N[Power[N[Sin[ky], $MachinePrecision], 2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision], -1.0], $MachinePrecision], 0.46], N[Sqrt[0.5], $MachinePrecision], N[Sqrt[1.0], $MachinePrecision]]
              
              \begin{array}{l}
              
              \\
              \begin{array}{l}
              \mathbf{if}\;{\left(\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}\right)}^{-1} \leq 0.46:\\
              \;\;\;\;\sqrt{0.5}\\
              
              \mathbf{else}:\\
              \;\;\;\;\sqrt{1}\\
              
              
              \end{array}
              \end{array}
              
              Derivation
              1. Split input into 2 regimes
              2. if (/.f64 #s(literal 1 binary64) (sqrt.f64 (+.f64 #s(literal 1 binary64) (*.f64 (pow.f64 (/.f64 (*.f64 #s(literal 2 binary64) l) Om) #s(literal 2 binary64)) (+.f64 (pow.f64 (sin.f64 kx) #s(literal 2 binary64)) (pow.f64 (sin.f64 ky) #s(literal 2 binary64))))))) < 0.46000000000000002

                1. Initial program 99.5%

                  \[\sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}}\right)} \]
                2. Add Preprocessing
                3. Taylor expanded in l around inf

                  \[\leadsto \sqrt{\color{blue}{\frac{1}{2}}} \]
                4. Step-by-step derivation
                  1. Applied rewrites97.9%

                    \[\leadsto \sqrt{\color{blue}{0.5}} \]

                  if 0.46000000000000002 < (/.f64 #s(literal 1 binary64) (sqrt.f64 (+.f64 #s(literal 1 binary64) (*.f64 (pow.f64 (/.f64 (*.f64 #s(literal 2 binary64) l) Om) #s(literal 2 binary64)) (+.f64 (pow.f64 (sin.f64 kx) #s(literal 2 binary64)) (pow.f64 (sin.f64 ky) #s(literal 2 binary64)))))))

                  1. Initial program 97.9%

                    \[\sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}}\right)} \]
                  2. Add Preprocessing
                  3. Taylor expanded in l around 0

                    \[\leadsto \sqrt{\color{blue}{1}} \]
                  4. Step-by-step derivation
                    1. Applied rewrites99.1%

                      \[\leadsto \sqrt{\color{blue}{1}} \]
                  5. Recombined 2 regimes into one program.
                  6. Final simplification98.5%

                    \[\leadsto \begin{array}{l} \mathbf{if}\;{\left(\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}\right)}^{-1} \leq 0.46:\\ \;\;\;\;\sqrt{0.5}\\ \mathbf{else}:\\ \;\;\;\;\sqrt{1}\\ \end{array} \]
                  7. Add Preprocessing

                  Alternative 5: 94.1% accurate, 2.3× speedup?

                  \[\begin{array}{l} \\ \sqrt{\frac{0.5}{\sqrt{\mathsf{fma}\left({\left(\frac{\ell \cdot \sin ky}{Om}\right)}^{2}, 4, 1\right)}} + 0.5} \end{array} \]
                  (FPCore (l Om kx ky)
                   :precision binary64
                   (sqrt (+ (/ 0.5 (sqrt (fma (pow (/ (* l (sin ky)) Om) 2.0) 4.0 1.0))) 0.5)))
                  double code(double l, double Om, double kx, double ky) {
                  	return sqrt(((0.5 / sqrt(fma(pow(((l * sin(ky)) / Om), 2.0), 4.0, 1.0))) + 0.5));
                  }
                  
                  function code(l, Om, kx, ky)
                  	return sqrt(Float64(Float64(0.5 / sqrt(fma((Float64(Float64(l * sin(ky)) / Om) ^ 2.0), 4.0, 1.0))) + 0.5))
                  end
                  
                  code[l_, Om_, kx_, ky_] := N[Sqrt[N[(N[(0.5 / N[Sqrt[N[(N[Power[N[(N[(l * N[Sin[ky], $MachinePrecision]), $MachinePrecision] / Om), $MachinePrecision], 2.0], $MachinePrecision] * 4.0 + 1.0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] + 0.5), $MachinePrecision]], $MachinePrecision]
                  
                  \begin{array}{l}
                  
                  \\
                  \sqrt{\frac{0.5}{\sqrt{\mathsf{fma}\left({\left(\frac{\ell \cdot \sin ky}{Om}\right)}^{2}, 4, 1\right)}} + 0.5}
                  \end{array}
                  
                  Derivation
                  1. Initial program 98.6%

                    \[\sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}}\right)} \]
                  2. Add Preprocessing
                  3. Taylor expanded in kx around 0

                    \[\leadsto \sqrt{\color{blue}{\frac{1}{2} \cdot \left(1 + \sqrt{\frac{1}{1 + 4 \cdot \frac{{\ell}^{2} \cdot {\sin ky}^{2}}{{Om}^{2}}}}\right)}} \]
                  4. Step-by-step derivation
                    1. +-commutativeN/A

                      \[\leadsto \sqrt{\frac{1}{2} \cdot \color{blue}{\left(\sqrt{\frac{1}{1 + 4 \cdot \frac{{\ell}^{2} \cdot {\sin ky}^{2}}{{Om}^{2}}}} + 1\right)}} \]
                    2. distribute-rgt-inN/A

                      \[\leadsto \sqrt{\color{blue}{\sqrt{\frac{1}{1 + 4 \cdot \frac{{\ell}^{2} \cdot {\sin ky}^{2}}{{Om}^{2}}}} \cdot \frac{1}{2} + 1 \cdot \frac{1}{2}}} \]
                    3. metadata-evalN/A

                      \[\leadsto \sqrt{\sqrt{\frac{1}{1 + 4 \cdot \frac{{\ell}^{2} \cdot {\sin ky}^{2}}{{Om}^{2}}}} \cdot \frac{1}{2} + \color{blue}{\frac{1}{2}}} \]
                    4. lower-fma.f64N/A

                      \[\leadsto \sqrt{\color{blue}{\mathsf{fma}\left(\sqrt{\frac{1}{1 + 4 \cdot \frac{{\ell}^{2} \cdot {\sin ky}^{2}}{{Om}^{2}}}}, \frac{1}{2}, \frac{1}{2}\right)}} \]
                  5. Applied rewrites83.3%

                    \[\leadsto \sqrt{\color{blue}{\mathsf{fma}\left(\sqrt{\frac{1}{\mathsf{fma}\left(\frac{{\sin ky}^{2}}{Om} \cdot \frac{\ell \cdot \ell}{Om}, 4, 1\right)}}, 0.5, 0.5\right)}} \]
                  6. Step-by-step derivation
                    1. Applied rewrites88.0%

                      \[\leadsto \sqrt{\mathsf{fma}\left(\sqrt{\frac{1}{\mathsf{fma}\left(\frac{{\sin ky}^{2}}{Om}, 4 \cdot \left(\frac{\ell}{Om} \cdot \ell\right), 1\right)}}, 0.5, 0.5\right)} \]
                    2. Applied rewrites94.4%

                      \[\leadsto \sqrt{\frac{0.5}{\sqrt{\mathsf{fma}\left({\left(\frac{\ell \cdot \sin ky}{Om}\right)}^{2}, 4, 1\right)}} + \color{blue}{0.5}} \]
                    3. Add Preprocessing

                    Alternative 6: 56.2% accurate, 52.8× speedup?

                    \[\begin{array}{l} \\ \sqrt{0.5} \end{array} \]
                    (FPCore (l Om kx ky) :precision binary64 (sqrt 0.5))
                    double code(double l, double Om, double kx, double ky) {
                    	return sqrt(0.5);
                    }
                    
                    real(8) function code(l, om, kx, ky)
                        real(8), intent (in) :: l
                        real(8), intent (in) :: om
                        real(8), intent (in) :: kx
                        real(8), intent (in) :: ky
                        code = sqrt(0.5d0)
                    end function
                    
                    public static double code(double l, double Om, double kx, double ky) {
                    	return Math.sqrt(0.5);
                    }
                    
                    def code(l, Om, kx, ky):
                    	return math.sqrt(0.5)
                    
                    function code(l, Om, kx, ky)
                    	return sqrt(0.5)
                    end
                    
                    function tmp = code(l, Om, kx, ky)
                    	tmp = sqrt(0.5);
                    end
                    
                    code[l_, Om_, kx_, ky_] := N[Sqrt[0.5], $MachinePrecision]
                    
                    \begin{array}{l}
                    
                    \\
                    \sqrt{0.5}
                    \end{array}
                    
                    Derivation
                    1. Initial program 98.6%

                      \[\sqrt{\frac{1}{2} \cdot \left(1 + \frac{1}{\sqrt{1 + {\left(\frac{2 \cdot \ell}{Om}\right)}^{2} \cdot \left({\sin kx}^{2} + {\sin ky}^{2}\right)}}\right)} \]
                    2. Add Preprocessing
                    3. Taylor expanded in l around inf

                      \[\leadsto \sqrt{\color{blue}{\frac{1}{2}}} \]
                    4. Step-by-step derivation
                      1. Applied rewrites54.7%

                        \[\leadsto \sqrt{\color{blue}{0.5}} \]
                      2. Add Preprocessing

                      Reproduce

                      ?
                      herbie shell --seed 2024302 
                      (FPCore (l Om kx ky)
                        :name "Toniolo and Linder, Equation (3a)"
                        :precision binary64
                        (sqrt (* (/ 1.0 2.0) (+ 1.0 (/ 1.0 (sqrt (+ 1.0 (* (pow (/ (* 2.0 l) Om) 2.0) (+ (pow (sin kx) 2.0) (pow (sin ky) 2.0))))))))))