
(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 10 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) (* (hypot a1 a2) (* (hypot a1 a2) (pow 2.0 -0.5)))))
double code(double a1, double a2, double th) {
return cos(th) * (hypot(a1, a2) * (hypot(a1, a2) * pow(2.0, -0.5)));
}
public static double code(double a1, double a2, double th) {
return Math.cos(th) * (Math.hypot(a1, a2) * (Math.hypot(a1, a2) * Math.pow(2.0, -0.5)));
}
def code(a1, a2, th): return math.cos(th) * (math.hypot(a1, a2) * (math.hypot(a1, a2) * math.pow(2.0, -0.5)))
function code(a1, a2, th) return Float64(cos(th) * Float64(hypot(a1, a2) * Float64(hypot(a1, a2) * (2.0 ^ -0.5)))) end
function tmp = code(a1, a2, th) tmp = cos(th) * (hypot(a1, a2) * (hypot(a1, a2) * (2.0 ^ -0.5))); end
code[a1_, a2_, th_] := N[(N[Cos[th], $MachinePrecision] * N[(N[Sqrt[a1 ^ 2 + a2 ^ 2], $MachinePrecision] * N[(N[Sqrt[a1 ^ 2 + a2 ^ 2], $MachinePrecision] * N[Power[2.0, -0.5], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\cos th \cdot \left(\mathsf{hypot}\left(a1, a2\right) \cdot \left(\mathsf{hypot}\left(a1, a2\right) \cdot {2}^{-0.5}\right)\right)
\end{array}
Initial program 99.5%
distribute-lft-out99.5%
associate-*l/99.6%
associate-*r/99.6%
fma-def99.6%
Simplified99.6%
fma-def99.6%
div-inv99.5%
add-sqr-sqrt99.5%
associate-*l*99.5%
hypot-def99.5%
hypot-def99.5%
pow1/299.5%
pow-flip99.6%
metadata-eval99.6%
Applied egg-rr99.6%
Final simplification99.6%
(FPCore (a1 a2 th) :precision binary64 (/ (* (sqrt 2.0) (* (cos th) (fma a2 a2 (* a1 a1)))) 2.0))
double code(double a1, double a2, double th) {
return (sqrt(2.0) * (cos(th) * fma(a2, a2, (a1 * a1)))) / 2.0;
}
function code(a1, a2, th) return Float64(Float64(sqrt(2.0) * Float64(cos(th) * fma(a2, a2, Float64(a1 * a1)))) / 2.0) end
code[a1_, a2_, th_] := N[(N[(N[Sqrt[2.0], $MachinePrecision] * N[(N[Cos[th], $MachinePrecision] * N[(a2 * a2 + N[(a1 * a1), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision] / 2.0), $MachinePrecision]
\begin{array}{l}
\\
\frac{\sqrt{2} \cdot \left(\cos th \cdot \mathsf{fma}\left(a2, a2, a1 \cdot a1\right)\right)}{2}
\end{array}
Initial program 99.5%
distribute-lft-out99.5%
associate-*l/99.6%
associate-*r/99.6%
fma-def99.6%
Simplified99.6%
fma-def99.6%
associate-*r/99.6%
associate-*l/99.5%
distribute-lft-in99.5%
+-commutative99.5%
associate-*l/99.6%
associate-*l/99.6%
frac-add99.3%
fma-def99.3%
*-commutative99.3%
add-sqr-sqrt99.6%
Applied egg-rr99.6%
fma-udef99.6%
*-commutative99.6%
distribute-rgt-out99.6%
*-commutative99.6%
distribute-lft-in99.6%
unpow299.6%
unpow299.6%
*-commutative99.6%
unpow299.6%
unpow299.6%
fma-def99.6%
Simplified99.6%
Final simplification99.6%
(FPCore (a1 a2 th) :precision binary64 (* (cos th) (/ (fma a1 a1 (* a2 a2)) (sqrt 2.0))))
double code(double a1, double a2, double th) {
return cos(th) * (fma(a1, a1, (a2 * a2)) / sqrt(2.0));
}
function code(a1, a2, th) return Float64(cos(th) * Float64(fma(a1, a1, Float64(a2 * a2)) / sqrt(2.0))) end
code[a1_, a2_, th_] := N[(N[Cos[th], $MachinePrecision] * N[(N[(a1 * a1 + N[(a2 * a2), $MachinePrecision]), $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\cos th \cdot \frac{\mathsf{fma}\left(a1, a1, a2 \cdot a2\right)}{\sqrt{2}}
\end{array}
Initial program 99.5%
distribute-lft-out99.5%
associate-*l/99.6%
associate-*r/99.6%
fma-def99.6%
Simplified99.6%
Final simplification99.6%
(FPCore (a1 a2 th) :precision binary64 (* (+ (* a1 a1) (* a2 a2)) (/ (cos th) (sqrt 2.0))))
double code(double a1, double a2, double th) {
return ((a1 * a1) + (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 = ((a1 * a1) + (a2 * a2)) * (cos(th) / sqrt(2.0d0))
end function
public static double code(double a1, double a2, double th) {
return ((a1 * a1) + (a2 * a2)) * (Math.cos(th) / Math.sqrt(2.0));
}
def code(a1, a2, th): return ((a1 * a1) + (a2 * a2)) * (math.cos(th) / math.sqrt(2.0))
function code(a1, a2, th) return Float64(Float64(Float64(a1 * a1) + Float64(a2 * a2)) * Float64(cos(th) / sqrt(2.0))) end
function tmp = code(a1, a2, th) tmp = ((a1 * a1) + (a2 * a2)) * (cos(th) / sqrt(2.0)); end
code[a1_, a2_, th_] := N[(N[(N[(a1 * a1), $MachinePrecision] + N[(a2 * a2), $MachinePrecision]), $MachinePrecision] * N[(N[Cos[th], $MachinePrecision] / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\left(a1 \cdot a1 + a2 \cdot a2\right) \cdot \frac{\cos th}{\sqrt{2}}
\end{array}
Initial program 99.5%
distribute-lft-out99.5%
Simplified99.5%
Final simplification99.5%
(FPCore (a1 a2 th) :precision binary64 (/ (+ (* a1 a1) (* a2 a2)) (/ (sqrt 2.0) (cos th))))
double code(double a1, double a2, double th) {
return ((a1 * a1) + (a2 * a2)) / (sqrt(2.0) / 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 = ((a1 * a1) + (a2 * a2)) / (sqrt(2.0d0) / cos(th))
end function
public static double code(double a1, double a2, double th) {
return ((a1 * a1) + (a2 * a2)) / (Math.sqrt(2.0) / Math.cos(th));
}
def code(a1, a2, th): return ((a1 * a1) + (a2 * a2)) / (math.sqrt(2.0) / math.cos(th))
function code(a1, a2, th) return Float64(Float64(Float64(a1 * a1) + Float64(a2 * a2)) / Float64(sqrt(2.0) / cos(th))) end
function tmp = code(a1, a2, th) tmp = ((a1 * a1) + (a2 * a2)) / (sqrt(2.0) / cos(th)); end
code[a1_, a2_, th_] := N[(N[(N[(a1 * a1), $MachinePrecision] + N[(a2 * a2), $MachinePrecision]), $MachinePrecision] / N[(N[Sqrt[2.0], $MachinePrecision] / N[Cos[th], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{a1 \cdot a1 + a2 \cdot a2}{\frac{\sqrt{2}}{\cos th}}
\end{array}
Initial program 99.5%
distribute-lft-out99.5%
associate-*l/99.6%
associate-*r/99.6%
fma-def99.6%
Simplified99.6%
Taylor expanded in th around inf 99.6%
associate-/l*99.6%
unpow299.6%
unpow299.6%
+-commutative99.6%
Simplified99.6%
Final simplification99.6%
(FPCore (a1 a2 th) :precision binary64 (* (cos th) (* a2 (* a2 (sqrt 0.5)))))
double code(double a1, double a2, double th) {
return cos(th) * (a2 * (a2 * sqrt(0.5)));
}
real(8) function code(a1, a2, th)
real(8), intent (in) :: a1
real(8), intent (in) :: a2
real(8), intent (in) :: th
code = cos(th) * (a2 * (a2 * sqrt(0.5d0)))
end function
public static double code(double a1, double a2, double th) {
return Math.cos(th) * (a2 * (a2 * Math.sqrt(0.5)));
}
def code(a1, a2, th): return math.cos(th) * (a2 * (a2 * math.sqrt(0.5)))
function code(a1, a2, th) return Float64(cos(th) * Float64(a2 * Float64(a2 * sqrt(0.5)))) end
function tmp = code(a1, a2, th) tmp = cos(th) * (a2 * (a2 * sqrt(0.5))); end
code[a1_, a2_, th_] := N[(N[Cos[th], $MachinePrecision] * N[(a2 * N[(a2 * N[Sqrt[0.5], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\cos th \cdot \left(a2 \cdot \left(a2 \cdot \sqrt{0.5}\right)\right)
\end{array}
Initial program 99.5%
distribute-lft-out99.5%
associate-*l/99.6%
associate-*r/99.6%
fma-def99.6%
Simplified99.6%
Taylor expanded in a1 around 0 51.6%
unpow251.6%
associate-/l*51.6%
associate-/r/51.6%
Simplified51.6%
div-inv51.6%
pow1/251.6%
pow-flip51.7%
metadata-eval51.7%
add-sqr-sqrt51.5%
sqrt-unprod51.7%
pow-prod-up51.7%
metadata-eval51.7%
metadata-eval51.7%
Applied egg-rr51.7%
Final simplification51.7%
(FPCore (a1 a2 th) :precision binary64 (if (<= a2 4.6e+185) (* (+ (* a1 a1) (* a2 a2)) (sqrt 0.5)) (* (sqrt 0.5) (* (* a2 a2) (+ (* -0.5 (* th th)) 1.0)))))
double code(double a1, double a2, double th) {
double tmp;
if (a2 <= 4.6e+185) {
tmp = ((a1 * a1) + (a2 * a2)) * sqrt(0.5);
} else {
tmp = sqrt(0.5) * ((a2 * a2) * ((-0.5 * (th * th)) + 1.0));
}
return tmp;
}
real(8) function code(a1, a2, th)
real(8), intent (in) :: a1
real(8), intent (in) :: a2
real(8), intent (in) :: th
real(8) :: tmp
if (a2 <= 4.6d+185) then
tmp = ((a1 * a1) + (a2 * a2)) * sqrt(0.5d0)
else
tmp = sqrt(0.5d0) * ((a2 * a2) * (((-0.5d0) * (th * th)) + 1.0d0))
end if
code = tmp
end function
public static double code(double a1, double a2, double th) {
double tmp;
if (a2 <= 4.6e+185) {
tmp = ((a1 * a1) + (a2 * a2)) * Math.sqrt(0.5);
} else {
tmp = Math.sqrt(0.5) * ((a2 * a2) * ((-0.5 * (th * th)) + 1.0));
}
return tmp;
}
def code(a1, a2, th): tmp = 0 if a2 <= 4.6e+185: tmp = ((a1 * a1) + (a2 * a2)) * math.sqrt(0.5) else: tmp = math.sqrt(0.5) * ((a2 * a2) * ((-0.5 * (th * th)) + 1.0)) return tmp
function code(a1, a2, th) tmp = 0.0 if (a2 <= 4.6e+185) tmp = Float64(Float64(Float64(a1 * a1) + Float64(a2 * a2)) * sqrt(0.5)); else tmp = Float64(sqrt(0.5) * Float64(Float64(a2 * a2) * Float64(Float64(-0.5 * Float64(th * th)) + 1.0))); end return tmp end
function tmp_2 = code(a1, a2, th) tmp = 0.0; if (a2 <= 4.6e+185) tmp = ((a1 * a1) + (a2 * a2)) * sqrt(0.5); else tmp = sqrt(0.5) * ((a2 * a2) * ((-0.5 * (th * th)) + 1.0)); end tmp_2 = tmp; end
code[a1_, a2_, th_] := If[LessEqual[a2, 4.6e+185], N[(N[(N[(a1 * a1), $MachinePrecision] + N[(a2 * a2), $MachinePrecision]), $MachinePrecision] * N[Sqrt[0.5], $MachinePrecision]), $MachinePrecision], N[(N[Sqrt[0.5], $MachinePrecision] * N[(N[(a2 * a2), $MachinePrecision] * N[(N[(-0.5 * N[(th * th), $MachinePrecision]), $MachinePrecision] + 1.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;a2 \leq 4.6 \cdot 10^{+185}:\\
\;\;\;\;\left(a1 \cdot a1 + a2 \cdot a2\right) \cdot \sqrt{0.5}\\
\mathbf{else}:\\
\;\;\;\;\sqrt{0.5} \cdot \left(\left(a2 \cdot a2\right) \cdot \left(-0.5 \cdot \left(th \cdot th\right) + 1\right)\right)\\
\end{array}
\end{array}
if a2 < 4.6000000000000003e185Initial program 99.5%
distribute-lft-out99.5%
Simplified99.5%
Taylor expanded in th around 0 65.0%
add-sqr-sqrt65.0%
sqrt-unprod65.0%
frac-times65.0%
metadata-eval65.0%
add-sqr-sqrt65.1%
metadata-eval65.1%
expm1-log1p-u64.7%
expm1-udef64.7%
Applied egg-rr64.7%
expm1-def64.7%
expm1-log1p65.1%
Simplified65.1%
if 4.6000000000000003e185 < a2 Initial program 100.0%
distribute-lft-out100.0%
associate-*l/100.0%
associate-*r/100.0%
fma-def100.0%
Simplified100.0%
Taylor expanded in a1 around 0 100.0%
unpow2100.0%
associate-*l*100.0%
Simplified100.0%
div-inv100.0%
pow1/2100.0%
pow-flip100.0%
metadata-eval100.0%
add-sqr-sqrt100.0%
sqrt-unprod100.0%
pow-prod-up100.0%
metadata-eval100.0%
metadata-eval100.0%
Applied egg-rr100.0%
Taylor expanded in th around 0 0.0%
associate-*r*0.0%
distribute-rgt1-in87.5%
unpow287.5%
unpow287.5%
Simplified87.5%
Final simplification67.2%
(FPCore (a1 a2 th) :precision binary64 (* (+ (* a1 a1) (* a2 a2)) (sqrt 0.5)))
double code(double a1, double a2, double th) {
return ((a1 * a1) + (a2 * a2)) * sqrt(0.5);
}
real(8) function code(a1, a2, th)
real(8), intent (in) :: a1
real(8), intent (in) :: a2
real(8), intent (in) :: th
code = ((a1 * a1) + (a2 * a2)) * sqrt(0.5d0)
end function
public static double code(double a1, double a2, double th) {
return ((a1 * a1) + (a2 * a2)) * Math.sqrt(0.5);
}
def code(a1, a2, th): return ((a1 * a1) + (a2 * a2)) * math.sqrt(0.5)
function code(a1, a2, th) return Float64(Float64(Float64(a1 * a1) + Float64(a2 * a2)) * sqrt(0.5)) end
function tmp = code(a1, a2, th) tmp = ((a1 * a1) + (a2 * a2)) * sqrt(0.5); end
code[a1_, a2_, th_] := N[(N[(N[(a1 * a1), $MachinePrecision] + N[(a2 * a2), $MachinePrecision]), $MachinePrecision] * N[Sqrt[0.5], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\left(a1 \cdot a1 + a2 \cdot a2\right) \cdot \sqrt{0.5}
\end{array}
Initial program 99.5%
distribute-lft-out99.5%
Simplified99.5%
Taylor expanded in th around 0 64.7%
add-sqr-sqrt64.7%
sqrt-unprod64.7%
frac-times64.7%
metadata-eval64.7%
add-sqr-sqrt64.8%
metadata-eval64.8%
expm1-log1p-u64.5%
expm1-udef64.5%
Applied egg-rr64.5%
expm1-def64.5%
expm1-log1p64.8%
Simplified64.8%
Final simplification64.8%
(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(a2 * Float64(a2 / sqrt(2.0))) end
function tmp = code(a1, a2, th) tmp = a2 * (a2 / sqrt(2.0)); end
code[a1_, a2_, th_] := N[(a2 * N[(a2 / N[Sqrt[2.0], $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
a2 \cdot \frac{a2}{\sqrt{2}}
\end{array}
Initial program 99.5%
distribute-lft-out99.5%
associate-*l/99.6%
associate-*r/99.6%
fma-def99.6%
Simplified99.6%
Taylor expanded in th around 0 64.8%
unpow264.8%
unpow264.8%
+-commutative64.8%
Simplified64.8%
Taylor expanded in a1 around 0 33.9%
unpow233.9%
associate-*r/33.9%
Simplified33.9%
Final simplification33.9%
(FPCore (a1 a2 th) :precision binary64 (* (* a2 a2) (sqrt 0.5)))
double code(double a1, double a2, double th) {
return (a2 * a2) * sqrt(0.5);
}
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(0.5d0)
end function
public static double code(double a1, double a2, double th) {
return (a2 * a2) * Math.sqrt(0.5);
}
def code(a1, a2, th): return (a2 * a2) * math.sqrt(0.5)
function code(a1, a2, th) return Float64(Float64(a2 * a2) * sqrt(0.5)) end
function tmp = code(a1, a2, th) tmp = (a2 * a2) * sqrt(0.5); end
code[a1_, a2_, th_] := N[(N[(a2 * a2), $MachinePrecision] * N[Sqrt[0.5], $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\left(a2 \cdot a2\right) \cdot \sqrt{0.5}
\end{array}
Initial program 99.5%
distribute-lft-out99.5%
associate-*l/99.6%
associate-*r/99.6%
fma-def99.6%
Simplified99.6%
Taylor expanded in a1 around 0 51.7%
unpow251.7%
associate-*l*51.7%
Simplified51.7%
div-inv51.6%
pow1/251.6%
pow-flip51.7%
metadata-eval51.7%
add-sqr-sqrt51.4%
sqrt-unprod51.7%
pow-prod-up51.7%
metadata-eval51.7%
metadata-eval51.7%
Applied egg-rr51.7%
Taylor expanded in th around 0 33.9%
Final simplification33.9%
herbie shell --seed 2023252
(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))))