
(FPCore (a1 a2 th) :precision binary64 (let* ((t_1 (/ (cos th) (sqrt 2.0)))) (+ (* t_1 (* a1 a1)) (* t_1 (* a2 a2)))))
double code(double a1, double a2, double th) {
double t_1 = cos(th) / sqrt(2.0);
return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
}
real(8) function code(a1, a2, th)
real(8), intent (in) :: a1
real(8), intent (in) :: a2
real(8), intent (in) :: th
real(8) :: t_1
t_1 = cos(th) / sqrt(2.0d0)
code = (t_1 * (a1 * a1)) + (t_1 * (a2 * a2))
end function
public static double code(double a1, double a2, double th) {
double t_1 = Math.cos(th) / Math.sqrt(2.0);
return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
}
def code(a1, a2, th): t_1 = math.cos(th) / math.sqrt(2.0) return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2))
function code(a1, a2, th) t_1 = Float64(cos(th) / sqrt(2.0)) return Float64(Float64(t_1 * Float64(a1 * a1)) + Float64(t_1 * Float64(a2 * a2))) end
function tmp = code(a1, a2, th) t_1 = cos(th) / sqrt(2.0); tmp = (t_1 * (a1 * a1)) + (t_1 * (a2 * a2)); end
code[a1_, a2_, th_] := Block[{t$95$1 = N[(N[Cos[th], $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]}, N[(N[(t$95$1 * N[(a1 * a1), $MachinePrecision]), $MachinePrecision] + N[(t$95$1 * N[(a2 * a2), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
t_1 := \frac{\cos th}{\sqrt{2}}\\
t\_1 \cdot \left(a1 \cdot a1\right) + t\_1 \cdot \left(a2 \cdot a2\right)
\end{array}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 11 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (a1 a2 th) :precision binary64 (let* ((t_1 (/ (cos th) (sqrt 2.0)))) (+ (* t_1 (* a1 a1)) (* t_1 (* a2 a2)))))
double code(double a1, double a2, double th) {
double t_1 = cos(th) / sqrt(2.0);
return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
}
real(8) function code(a1, a2, th)
real(8), intent (in) :: a1
real(8), intent (in) :: a2
real(8), intent (in) :: th
real(8) :: t_1
t_1 = cos(th) / sqrt(2.0d0)
code = (t_1 * (a1 * a1)) + (t_1 * (a2 * a2))
end function
public static double code(double a1, double a2, double th) {
double t_1 = Math.cos(th) / Math.sqrt(2.0);
return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2));
}
def code(a1, a2, th): t_1 = math.cos(th) / math.sqrt(2.0) return (t_1 * (a1 * a1)) + (t_1 * (a2 * a2))
function code(a1, a2, th) t_1 = Float64(cos(th) / sqrt(2.0)) return Float64(Float64(t_1 * Float64(a1 * a1)) + Float64(t_1 * Float64(a2 * a2))) end
function tmp = code(a1, a2, th) t_1 = cos(th) / sqrt(2.0); tmp = (t_1 * (a1 * a1)) + (t_1 * (a2 * a2)); end
code[a1_, a2_, th_] := Block[{t$95$1 = N[(N[Cos[th], $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]}, N[(N[(t$95$1 * N[(a1 * a1), $MachinePrecision]), $MachinePrecision] + N[(t$95$1 * N[(a2 * a2), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
t_1 := \frac{\cos th}{\sqrt{2}}\\
t\_1 \cdot \left(a1 \cdot a1\right) + t\_1 \cdot \left(a2 \cdot a2\right)
\end{array}
\end{array}
(FPCore (a1 a2 th) :precision binary64 (/ (cos th) (/ (sqrt 2.0) (fma a1 a1 (* a2 a2)))))
double code(double a1, double a2, double th) {
return cos(th) / (sqrt(2.0) / fma(a1, a1, (a2 * a2)));
}
function code(a1, a2, th) return Float64(cos(th) / Float64(sqrt(2.0) / fma(a1, a1, Float64(a2 * a2)))) end
code[a1_, a2_, th_] := N[(N[Cos[th], $MachinePrecision] / N[(N[Sqrt[2.0], $MachinePrecision] / N[(a1 * a1 + N[(a2 * a2), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\cos th}{\frac{\sqrt{2}}{\mathsf{fma}\left(a1, a1, a2 \cdot a2\right)}}
\end{array}
Initial program 99.6%
lift-+.f64N/A
lift-*.f64N/A
lift-*.f64N/A
distribute-lft-outN/A
lift-/.f64N/A
clear-numN/A
associate-*l/N/A
clear-numN/A
lower-/.f64N/A
*-lft-identityN/A
lower-/.f64N/A
lower-/.f64N/A
+-commutativeN/A
lift-*.f64N/A
lower-fma.f6499.7
Applied rewrites99.7%
lift-/.f64N/A
lift-/.f64N/A
associate-/l/N/A
associate-/r*N/A
lower-/.f64N/A
lower-/.f6499.6
Applied rewrites99.6%
lift-/.f64N/A
lift-/.f64N/A
clear-numN/A
lower-/.f6499.7
lift-*.f64N/A
lift-fma.f64N/A
+-commutativeN/A
lower-fma.f64N/A
lower-*.f6499.7
Applied rewrites99.7%
(FPCore (a1 a2 th)
:precision binary64
(let* ((t_1 (/ (cos th) (sqrt 2.0))))
(if (<= (+ (* t_1 (* a2 a2)) (* t_1 (* a1 a1))) -1e-152)
(* (* (fma (* th th) -0.5 1.0) a2) (/ a2 (sqrt 2.0)))
(/ (fma a2 a2 (* a1 a1)) (sqrt 2.0)))))
double code(double a1, double a2, double th) {
double t_1 = cos(th) / sqrt(2.0);
double tmp;
if (((t_1 * (a2 * a2)) + (t_1 * (a1 * a1))) <= -1e-152) {
tmp = (fma((th * th), -0.5, 1.0) * a2) * (a2 / sqrt(2.0));
} else {
tmp = fma(a2, a2, (a1 * a1)) / sqrt(2.0);
}
return tmp;
}
function code(a1, a2, th) t_1 = Float64(cos(th) / sqrt(2.0)) tmp = 0.0 if (Float64(Float64(t_1 * Float64(a2 * a2)) + Float64(t_1 * Float64(a1 * a1))) <= -1e-152) tmp = Float64(Float64(fma(Float64(th * th), -0.5, 1.0) * a2) * Float64(a2 / sqrt(2.0))); else tmp = Float64(fma(a2, a2, Float64(a1 * a1)) / sqrt(2.0)); end return tmp end
code[a1_, a2_, th_] := Block[{t$95$1 = N[(N[Cos[th], $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]}, If[LessEqual[N[(N[(t$95$1 * N[(a2 * a2), $MachinePrecision]), $MachinePrecision] + N[(t$95$1 * N[(a1 * a1), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], -1e-152], N[(N[(N[(N[(th * th), $MachinePrecision] * -0.5 + 1.0), $MachinePrecision] * a2), $MachinePrecision] * N[(a2 / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(N[(a2 * a2 + N[(a1 * a1), $MachinePrecision]), $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}
\\
\begin{array}{l}
t_1 := \frac{\cos th}{\sqrt{2}}\\
\mathbf{if}\;t\_1 \cdot \left(a2 \cdot a2\right) + t\_1 \cdot \left(a1 \cdot a1\right) \leq -1 \cdot 10^{-152}:\\
\;\;\;\;\left(\mathsf{fma}\left(th \cdot th, -0.5, 1\right) \cdot a2\right) \cdot \frac{a2}{\sqrt{2}}\\
\mathbf{else}:\\
\;\;\;\;\frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\sqrt{2}}\\
\end{array}
\end{array}
if (+.f64 (*.f64 (/.f64 (cos.f64 th) (sqrt.f64 #s(literal 2 binary64))) (*.f64 a1 a1)) (*.f64 (/.f64 (cos.f64 th) (sqrt.f64 #s(literal 2 binary64))) (*.f64 a2 a2))) < -1.00000000000000007e-152Initial program 99.6%
Taylor expanded in a1 around 0
*-commutativeN/A
unpow2N/A
associate-*r*N/A
associate-/l*N/A
lower-*.f64N/A
lower-*.f64N/A
lower-cos.f64N/A
lower-/.f64N/A
lower-sqrt.f6444.6
Applied rewrites44.6%
Taylor expanded in th around 0
Applied rewrites44.0%
if -1.00000000000000007e-152 < (+.f64 (*.f64 (/.f64 (cos.f64 th) (sqrt.f64 #s(literal 2 binary64))) (*.f64 a1 a1)) (*.f64 (/.f64 (cos.f64 th) (sqrt.f64 #s(literal 2 binary64))) (*.f64 a2 a2))) Initial program 99.6%
lift-+.f64N/A
lift-*.f64N/A
lift-*.f64N/A
distribute-lft-outN/A
*-commutativeN/A
lift-/.f64N/A
clear-numN/A
un-div-invN/A
lower-/.f64N/A
+-commutativeN/A
lift-*.f64N/A
lower-fma.f64N/A
lower-/.f6499.7
Applied rewrites99.7%
Taylor expanded in th around 0
lower-sqrt.f6482.9
Applied rewrites82.9%
Final simplification72.6%
(FPCore (a1 a2 th) :precision binary64 (* (/ (fma a2 a2 (* a1 a1)) (sqrt 2.0)) (cos th)))
double code(double a1, double a2, double th) {
return (fma(a2, a2, (a1 * a1)) / sqrt(2.0)) * cos(th);
}
function code(a1, a2, th) return Float64(Float64(fma(a2, a2, Float64(a1 * a1)) / sqrt(2.0)) * cos(th)) end
code[a1_, a2_, th_] := N[(N[(N[(a2 * a2 + N[(a1 * a1), $MachinePrecision]), $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision] * N[Cos[th], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\sqrt{2}} \cdot \cos th
\end{array}
Initial program 99.6%
lift-+.f64N/A
lift-*.f64N/A
lift-*.f64N/A
distribute-lft-outN/A
lift-/.f64N/A
div-invN/A
associate-*l*N/A
*-commutativeN/A
lower-*.f64N/A
associate-*l/N/A
*-lft-identityN/A
lower-/.f64N/A
+-commutativeN/A
lift-*.f64N/A
lower-fma.f6499.6
Applied rewrites99.6%
(FPCore (a1 a2 th) :precision binary64 (/ (* (* a2 a2) (cos th)) (sqrt 2.0)))
double code(double a1, double a2, double th) {
return ((a2 * a2) * cos(th)) / sqrt(2.0);
}
real(8) function code(a1, a2, th)
real(8), intent (in) :: a1
real(8), intent (in) :: a2
real(8), intent (in) :: th
code = ((a2 * a2) * cos(th)) / sqrt(2.0d0)
end function
public static double code(double a1, double a2, double th) {
return ((a2 * a2) * Math.cos(th)) / Math.sqrt(2.0);
}
def code(a1, a2, th): return ((a2 * a2) * math.cos(th)) / math.sqrt(2.0)
function code(a1, a2, th) return Float64(Float64(Float64(a2 * a2) * cos(th)) / sqrt(2.0)) end
function tmp = code(a1, a2, th) tmp = ((a2 * a2) * cos(th)) / sqrt(2.0); end
code[a1_, a2_, th_] := N[(N[(N[(a2 * a2), $MachinePrecision] * N[Cos[th], $MachinePrecision]), $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\left(a2 \cdot a2\right) \cdot \cos th}{\sqrt{2}}
\end{array}
Initial program 99.6%
lift-+.f64N/A
lift-*.f64N/A
lift-*.f64N/A
distribute-lft-outN/A
lift-/.f64N/A
associate-*l/N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f64N/A
+-commutativeN/A
lift-*.f64N/A
lower-fma.f6499.6
Applied rewrites99.6%
Taylor expanded in a1 around 0
unpow2N/A
lower-*.f6455.3
Applied rewrites55.3%
(FPCore (a1 a2 th) :precision binary64 (* (* (/ a2 (sqrt 2.0)) a2) (cos th)))
double code(double a1, double a2, double th) {
return ((a2 / sqrt(2.0)) * a2) * cos(th);
}
real(8) function code(a1, a2, th)
real(8), intent (in) :: a1
real(8), intent (in) :: a2
real(8), intent (in) :: th
code = ((a2 / sqrt(2.0d0)) * a2) * cos(th)
end function
public static double code(double a1, double a2, double th) {
return ((a2 / Math.sqrt(2.0)) * a2) * Math.cos(th);
}
def code(a1, a2, th): return ((a2 / math.sqrt(2.0)) * a2) * math.cos(th)
function code(a1, a2, th) return Float64(Float64(Float64(a2 / sqrt(2.0)) * a2) * cos(th)) end
function tmp = code(a1, a2, th) tmp = ((a2 / sqrt(2.0)) * a2) * cos(th); end
code[a1_, a2_, th_] := N[(N[(N[(a2 / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision] * a2), $MachinePrecision] * N[Cos[th], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\left(\frac{a2}{\sqrt{2}} \cdot a2\right) \cdot \cos th
\end{array}
Initial program 99.6%
Taylor expanded in a1 around 0
*-commutativeN/A
unpow2N/A
associate-*r*N/A
associate-/l*N/A
lower-*.f64N/A
lower-*.f64N/A
lower-cos.f64N/A
lower-/.f64N/A
lower-sqrt.f6455.3
Applied rewrites55.3%
Applied rewrites55.3%
(FPCore (a1 a2 th) :precision binary64 (* (* a2 (cos th)) (/ a2 (sqrt 2.0))))
double code(double a1, double a2, double th) {
return (a2 * cos(th)) * (a2 / sqrt(2.0));
}
real(8) function code(a1, a2, th)
real(8), intent (in) :: a1
real(8), intent (in) :: a2
real(8), intent (in) :: th
code = (a2 * cos(th)) * (a2 / sqrt(2.0d0))
end function
public static double code(double a1, double a2, double th) {
return (a2 * Math.cos(th)) * (a2 / Math.sqrt(2.0));
}
def code(a1, a2, th): return (a2 * math.cos(th)) * (a2 / math.sqrt(2.0))
function code(a1, a2, th) return Float64(Float64(a2 * cos(th)) * Float64(a2 / sqrt(2.0))) end
function tmp = code(a1, a2, th) tmp = (a2 * cos(th)) * (a2 / sqrt(2.0)); end
code[a1_, a2_, th_] := N[(N[(a2 * N[Cos[th], $MachinePrecision]), $MachinePrecision] * N[(a2 / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\left(a2 \cdot \cos th\right) \cdot \frac{a2}{\sqrt{2}}
\end{array}
Initial program 99.6%
Taylor expanded in a1 around 0
*-commutativeN/A
unpow2N/A
associate-*r*N/A
associate-/l*N/A
lower-*.f64N/A
lower-*.f64N/A
lower-cos.f64N/A
lower-/.f64N/A
lower-sqrt.f6455.3
Applied rewrites55.3%
Final simplification55.3%
(FPCore (a1 a2 th) :precision binary64 (/ (fma a2 a2 (* a1 a1)) (sqrt 2.0)))
double code(double a1, double a2, double th) {
return fma(a2, a2, (a1 * a1)) / sqrt(2.0);
}
function code(a1, a2, th) return Float64(fma(a2, a2, Float64(a1 * a1)) / sqrt(2.0)) end
code[a1_, a2_, th_] := N[(N[(a2 * a2 + N[(a1 * a1), $MachinePrecision]), $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\mathsf{fma}\left(a2, a2, a1 \cdot a1\right)}{\sqrt{2}}
\end{array}
Initial program 99.6%
lift-+.f64N/A
lift-*.f64N/A
lift-*.f64N/A
distribute-lft-outN/A
*-commutativeN/A
lift-/.f64N/A
clear-numN/A
un-div-invN/A
lower-/.f64N/A
+-commutativeN/A
lift-*.f64N/A
lower-fma.f64N/A
lower-/.f6499.7
Applied rewrites99.7%
Taylor expanded in th around 0
lower-sqrt.f6461.0
Applied rewrites61.0%
(FPCore (a1 a2 th) :precision binary64 (/ (* a2 a2) (sqrt 2.0)))
double code(double a1, double a2, double th) {
return (a2 * a2) / sqrt(2.0);
}
real(8) function code(a1, a2, th)
real(8), intent (in) :: a1
real(8), intent (in) :: a2
real(8), intent (in) :: th
code = (a2 * a2) / sqrt(2.0d0)
end function
public static double code(double a1, double a2, double th) {
return (a2 * a2) / Math.sqrt(2.0);
}
def code(a1, a2, th): return (a2 * a2) / math.sqrt(2.0)
function code(a1, a2, th) return Float64(Float64(a2 * a2) / sqrt(2.0)) end
function tmp = code(a1, a2, th) tmp = (a2 * a2) / sqrt(2.0); end
code[a1_, a2_, th_] := N[(N[(a2 * a2), $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{a2 \cdot a2}{\sqrt{2}}
\end{array}
Initial program 99.6%
lift-+.f64N/A
lift-*.f64N/A
lift-*.f64N/A
distribute-lft-outN/A
lift-/.f64N/A
associate-*l/N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f64N/A
+-commutativeN/A
lift-*.f64N/A
lower-fma.f6499.6
Applied rewrites99.6%
Taylor expanded in a1 around 0
*-commutativeN/A
unpow2N/A
associate-*r*N/A
*-commutativeN/A
lower-*.f64N/A
*-commutativeN/A
lower-*.f64N/A
lower-cos.f6455.3
Applied rewrites55.3%
Taylor expanded in th around 0
Applied rewrites36.9%
(FPCore (a1 a2 th) :precision binary64 (* (/ a2 (sqrt 2.0)) a2))
double code(double a1, double a2, double th) {
return (a2 / sqrt(2.0)) * a2;
}
real(8) function code(a1, a2, th)
real(8), intent (in) :: a1
real(8), intent (in) :: a2
real(8), intent (in) :: th
code = (a2 / sqrt(2.0d0)) * a2
end function
public static double code(double a1, double a2, double th) {
return (a2 / Math.sqrt(2.0)) * a2;
}
def code(a1, a2, th): return (a2 / math.sqrt(2.0)) * a2
function code(a1, a2, th) return Float64(Float64(a2 / sqrt(2.0)) * a2) end
function tmp = code(a1, a2, th) tmp = (a2 / sqrt(2.0)) * a2; end
code[a1_, a2_, th_] := N[(N[(a2 / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision] * a2), $MachinePrecision]
\begin{array}{l}
\\
\frac{a2}{\sqrt{2}} \cdot a2
\end{array}
Initial program 99.6%
Taylor expanded in th around 0
+-commutativeN/A
unpow2N/A
associate-*l/N/A
lower-fma.f64N/A
lower-/.f64N/A
lower-sqrt.f64N/A
unpow2N/A
associate-*l/N/A
lower-*.f64N/A
lower-/.f64N/A
lower-sqrt.f6461.0
Applied rewrites61.0%
Taylor expanded in a1 around 0
Applied rewrites36.9%
(FPCore (a1 a2 th) :precision binary64 (* (* (sqrt 0.5) a2) a2))
double code(double a1, double a2, double th) {
return (sqrt(0.5) * a2) * a2;
}
real(8) function code(a1, a2, th)
real(8), intent (in) :: a1
real(8), intent (in) :: a2
real(8), intent (in) :: th
code = (sqrt(0.5d0) * a2) * a2
end function
public static double code(double a1, double a2, double th) {
return (Math.sqrt(0.5) * a2) * a2;
}
def code(a1, a2, th): return (math.sqrt(0.5) * a2) * a2
function code(a1, a2, th) return Float64(Float64(sqrt(0.5) * a2) * a2) end
function tmp = code(a1, a2, th) tmp = (sqrt(0.5) * a2) * a2; end
code[a1_, a2_, th_] := N[(N[(N[Sqrt[0.5], $MachinePrecision] * a2), $MachinePrecision] * a2), $MachinePrecision]
\begin{array}{l}
\\
\left(\sqrt{0.5} \cdot a2\right) \cdot a2
\end{array}
Initial program 99.6%
Taylor expanded in th around 0
+-commutativeN/A
unpow2N/A
associate-*l/N/A
lower-fma.f64N/A
lower-/.f64N/A
lower-sqrt.f64N/A
unpow2N/A
associate-*l/N/A
lower-*.f64N/A
lower-/.f64N/A
lower-sqrt.f6461.0
Applied rewrites61.0%
Applied rewrites61.0%
Taylor expanded in a1 around 0
Applied rewrites36.9%
(FPCore (a1 a2 th) :precision binary64 (* (sqrt 0.5) (* a2 a2)))
double code(double a1, double a2, double th) {
return sqrt(0.5) * (a2 * a2);
}
real(8) function code(a1, a2, th)
real(8), intent (in) :: a1
real(8), intent (in) :: a2
real(8), intent (in) :: th
code = sqrt(0.5d0) * (a2 * a2)
end function
public static double code(double a1, double a2, double th) {
return Math.sqrt(0.5) * (a2 * a2);
}
def code(a1, a2, th): return math.sqrt(0.5) * (a2 * a2)
function code(a1, a2, th) return Float64(sqrt(0.5) * Float64(a2 * a2)) end
function tmp = code(a1, a2, th) tmp = sqrt(0.5) * (a2 * a2); end
code[a1_, a2_, th_] := N[(N[Sqrt[0.5], $MachinePrecision] * N[(a2 * a2), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\sqrt{0.5} \cdot \left(a2 \cdot a2\right)
\end{array}
Initial program 99.6%
Taylor expanded in th around 0
+-commutativeN/A
unpow2N/A
associate-*l/N/A
lower-fma.f64N/A
lower-/.f64N/A
lower-sqrt.f64N/A
unpow2N/A
associate-*l/N/A
lower-*.f64N/A
lower-/.f64N/A
lower-sqrt.f6461.0
Applied rewrites61.0%
Applied rewrites61.0%
Taylor expanded in a1 around 0
Applied rewrites36.9%
Applied rewrites36.9%
Final simplification36.9%
herbie shell --seed 2024276
(FPCore (a1 a2 th)
:name "Migdal et al, Equation (64)"
:precision binary64
(+ (* (/ (cos th) (sqrt 2.0)) (* a1 a1)) (* (/ (cos th) (sqrt 2.0)) (* a2 a2))))