
(FPCore (x y) :precision binary64 (let* ((t_0 (* (* y 4.0) y))) (/ (- (* x x) t_0) (+ (* x x) t_0))))
double code(double x, double y) {
double t_0 = (y * 4.0) * y;
return ((x * x) - t_0) / ((x * x) + t_0);
}
real(8) function code(x, y)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8) :: t_0
t_0 = (y * 4.0d0) * y
code = ((x * x) - t_0) / ((x * x) + t_0)
end function
public static double code(double x, double y) {
double t_0 = (y * 4.0) * y;
return ((x * x) - t_0) / ((x * x) + t_0);
}
def code(x, y): t_0 = (y * 4.0) * y return ((x * x) - t_0) / ((x * x) + t_0)
function code(x, y) t_0 = Float64(Float64(y * 4.0) * y) return Float64(Float64(Float64(x * x) - t_0) / Float64(Float64(x * x) + t_0)) end
function tmp = code(x, y) t_0 = (y * 4.0) * y; tmp = ((x * x) - t_0) / ((x * x) + t_0); end
code[x_, y_] := Block[{t$95$0 = N[(N[(y * 4.0), $MachinePrecision] * y), $MachinePrecision]}, N[(N[(N[(x * x), $MachinePrecision] - t$95$0), $MachinePrecision] / N[(N[(x * x), $MachinePrecision] + t$95$0), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(y \cdot 4\right) \cdot y\\
\frac{x \cdot x - t\_0}{x \cdot x + t\_0}
\end{array}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 6 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (x y) :precision binary64 (let* ((t_0 (* (* y 4.0) y))) (/ (- (* x x) t_0) (+ (* x x) t_0))))
double code(double x, double y) {
double t_0 = (y * 4.0) * y;
return ((x * x) - t_0) / ((x * x) + t_0);
}
real(8) function code(x, y)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8) :: t_0
t_0 = (y * 4.0d0) * y
code = ((x * x) - t_0) / ((x * x) + t_0)
end function
public static double code(double x, double y) {
double t_0 = (y * 4.0) * y;
return ((x * x) - t_0) / ((x * x) + t_0);
}
def code(x, y): t_0 = (y * 4.0) * y return ((x * x) - t_0) / ((x * x) + t_0)
function code(x, y) t_0 = Float64(Float64(y * 4.0) * y) return Float64(Float64(Float64(x * x) - t_0) / Float64(Float64(x * x) + t_0)) end
function tmp = code(x, y) t_0 = (y * 4.0) * y; tmp = ((x * x) - t_0) / ((x * x) + t_0); end
code[x_, y_] := Block[{t$95$0 = N[(N[(y * 4.0), $MachinePrecision] * y), $MachinePrecision]}, N[(N[(N[(x * x), $MachinePrecision] - t$95$0), $MachinePrecision] / N[(N[(x * x), $MachinePrecision] + t$95$0), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(y \cdot 4\right) \cdot y\\
\frac{x \cdot x - t\_0}{x \cdot x + t\_0}
\end{array}
\end{array}
(FPCore (x y)
:precision binary64
(let* ((t_0 (* (* y 4.0) y)))
(if (<= t_0 4e-227)
(fma (* -8.0 (/ y x)) (/ y x) 1.0)
(if (<= t_0 2e+154)
(/ (fma -4.0 (* y y) (* x x)) (fma (* 4.0 y) y (* x x)))
(- (* (* 0.5 (/ x y)) (/ x y)) 1.0)))))
double code(double x, double y) {
double t_0 = (y * 4.0) * y;
double tmp;
if (t_0 <= 4e-227) {
tmp = fma((-8.0 * (y / x)), (y / x), 1.0);
} else if (t_0 <= 2e+154) {
tmp = fma(-4.0, (y * y), (x * x)) / fma((4.0 * y), y, (x * x));
} else {
tmp = ((0.5 * (x / y)) * (x / y)) - 1.0;
}
return tmp;
}
function code(x, y) t_0 = Float64(Float64(y * 4.0) * y) tmp = 0.0 if (t_0 <= 4e-227) tmp = fma(Float64(-8.0 * Float64(y / x)), Float64(y / x), 1.0); elseif (t_0 <= 2e+154) tmp = Float64(fma(-4.0, Float64(y * y), Float64(x * x)) / fma(Float64(4.0 * y), y, Float64(x * x))); else tmp = Float64(Float64(Float64(0.5 * Float64(x / y)) * Float64(x / y)) - 1.0); end return tmp end
code[x_, y_] := Block[{t$95$0 = N[(N[(y * 4.0), $MachinePrecision] * y), $MachinePrecision]}, If[LessEqual[t$95$0, 4e-227], N[(N[(-8.0 * N[(y / x), $MachinePrecision]), $MachinePrecision] * N[(y / x), $MachinePrecision] + 1.0), $MachinePrecision], If[LessEqual[t$95$0, 2e+154], N[(N[(-4.0 * N[(y * y), $MachinePrecision] + N[(x * x), $MachinePrecision]), $MachinePrecision] / N[(N[(4.0 * y), $MachinePrecision] * y + N[(x * x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(N[(N[(0.5 * N[(x / y), $MachinePrecision]), $MachinePrecision] * N[(x / y), $MachinePrecision]), $MachinePrecision] - 1.0), $MachinePrecision]]]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(y \cdot 4\right) \cdot y\\
\mathbf{if}\;t\_0 \leq 4 \cdot 10^{-227}:\\
\;\;\;\;\mathsf{fma}\left(-8 \cdot \frac{y}{x}, \frac{y}{x}, 1\right)\\
\mathbf{elif}\;t\_0 \leq 2 \cdot 10^{+154}:\\
\;\;\;\;\frac{\mathsf{fma}\left(-4, y \cdot y, x \cdot x\right)}{\mathsf{fma}\left(4 \cdot y, y, x \cdot x\right)}\\
\mathbf{else}:\\
\;\;\;\;\left(0.5 \cdot \frac{x}{y}\right) \cdot \frac{x}{y} - 1\\
\end{array}
\end{array}
if (*.f64 (*.f64 y #s(literal 4 binary64)) y) < 3.99999999999999978e-227Initial program 54.3%
Taylor expanded in x around inf
associate--l+N/A
distribute-rgt-out--N/A
metadata-evalN/A
*-commutativeN/A
+-commutativeN/A
unpow2N/A
unpow2N/A
times-fracN/A
associate-*r*N/A
lower-fma.f64N/A
lower-*.f64N/A
lower-/.f64N/A
lower-/.f6491.4
Applied rewrites91.4%
if 3.99999999999999978e-227 < (*.f64 (*.f64 y #s(literal 4 binary64)) y) < 2.00000000000000007e154Initial program 80.5%
lift--.f64N/A
lift-*.f64N/A
fp-cancel-sub-sign-invN/A
+-commutativeN/A
lift-*.f64N/A
*-commutativeN/A
distribute-lft-neg-inN/A
associate-*l*N/A
lower-fma.f64N/A
metadata-evalN/A
lower-*.f6480.5
lift-+.f64N/A
+-commutativeN/A
lift-*.f64N/A
lower-fma.f6480.5
lift-*.f64N/A
*-commutativeN/A
lower-*.f6480.5
Applied rewrites80.5%
if 2.00000000000000007e154 < (*.f64 (*.f64 y #s(literal 4 binary64)) y) Initial program 25.0%
Taylor expanded in x around 0
*-lft-identityN/A
associate-*l/N/A
associate-*l*N/A
*-commutativeN/A
lower--.f64N/A
*-commutativeN/A
associate-*l*N/A
associate-*l/N/A
*-lft-identityN/A
unpow2N/A
unpow2N/A
times-fracN/A
associate-*r*N/A
lower-*.f64N/A
lower-*.f64N/A
lower-/.f64N/A
lower-/.f6485.0
Applied rewrites85.0%
(FPCore (x y) :precision binary64 (if (<= (* (* y 4.0) y) 1e-109) (fma (* -8.0 (/ y x)) (/ y x) 1.0) (- (* (* 0.5 (/ x y)) (/ x y)) 1.0)))
double code(double x, double y) {
double tmp;
if (((y * 4.0) * y) <= 1e-109) {
tmp = fma((-8.0 * (y / x)), (y / x), 1.0);
} else {
tmp = ((0.5 * (x / y)) * (x / y)) - 1.0;
}
return tmp;
}
function code(x, y) tmp = 0.0 if (Float64(Float64(y * 4.0) * y) <= 1e-109) tmp = fma(Float64(-8.0 * Float64(y / x)), Float64(y / x), 1.0); else tmp = Float64(Float64(Float64(0.5 * Float64(x / y)) * Float64(x / y)) - 1.0); end return tmp end
code[x_, y_] := If[LessEqual[N[(N[(y * 4.0), $MachinePrecision] * y), $MachinePrecision], 1e-109], N[(N[(-8.0 * N[(y / x), $MachinePrecision]), $MachinePrecision] * N[(y / x), $MachinePrecision] + 1.0), $MachinePrecision], N[(N[(N[(0.5 * N[(x / y), $MachinePrecision]), $MachinePrecision] * N[(x / y), $MachinePrecision]), $MachinePrecision] - 1.0), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\left(y \cdot 4\right) \cdot y \leq 10^{-109}:\\
\;\;\;\;\mathsf{fma}\left(-8 \cdot \frac{y}{x}, \frac{y}{x}, 1\right)\\
\mathbf{else}:\\
\;\;\;\;\left(0.5 \cdot \frac{x}{y}\right) \cdot \frac{x}{y} - 1\\
\end{array}
\end{array}
if (*.f64 (*.f64 y #s(literal 4 binary64)) y) < 9.9999999999999999e-110Initial program 62.4%
Taylor expanded in x around inf
associate--l+N/A
distribute-rgt-out--N/A
metadata-evalN/A
*-commutativeN/A
+-commutativeN/A
unpow2N/A
unpow2N/A
times-fracN/A
associate-*r*N/A
lower-fma.f64N/A
lower-*.f64N/A
lower-/.f64N/A
lower-/.f6486.6
Applied rewrites86.6%
if 9.9999999999999999e-110 < (*.f64 (*.f64 y #s(literal 4 binary64)) y) Initial program 46.3%
Taylor expanded in x around 0
*-lft-identityN/A
associate-*l/N/A
associate-*l*N/A
*-commutativeN/A
lower--.f64N/A
*-commutativeN/A
associate-*l*N/A
associate-*l/N/A
*-lft-identityN/A
unpow2N/A
unpow2N/A
times-fracN/A
associate-*r*N/A
lower-*.f64N/A
lower-*.f64N/A
lower-/.f64N/A
lower-/.f6476.0
Applied rewrites76.0%
(FPCore (x y) :precision binary64 (if (<= (* (* y 4.0) y) 1e-109) (fma (* -8.0 (/ y x)) (/ y x) 1.0) (fma (/ 0.5 y) (* x (/ x y)) -1.0)))
double code(double x, double y) {
double tmp;
if (((y * 4.0) * y) <= 1e-109) {
tmp = fma((-8.0 * (y / x)), (y / x), 1.0);
} else {
tmp = fma((0.5 / y), (x * (x / y)), -1.0);
}
return tmp;
}
function code(x, y) tmp = 0.0 if (Float64(Float64(y * 4.0) * y) <= 1e-109) tmp = fma(Float64(-8.0 * Float64(y / x)), Float64(y / x), 1.0); else tmp = fma(Float64(0.5 / y), Float64(x * Float64(x / y)), -1.0); end return tmp end
code[x_, y_] := If[LessEqual[N[(N[(y * 4.0), $MachinePrecision] * y), $MachinePrecision], 1e-109], N[(N[(-8.0 * N[(y / x), $MachinePrecision]), $MachinePrecision] * N[(y / x), $MachinePrecision] + 1.0), $MachinePrecision], N[(N[(0.5 / y), $MachinePrecision] * N[(x * N[(x / y), $MachinePrecision]), $MachinePrecision] + -1.0), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\left(y \cdot 4\right) \cdot y \leq 10^{-109}:\\
\;\;\;\;\mathsf{fma}\left(-8 \cdot \frac{y}{x}, \frac{y}{x}, 1\right)\\
\mathbf{else}:\\
\;\;\;\;\mathsf{fma}\left(\frac{0.5}{y}, x \cdot \frac{x}{y}, -1\right)\\
\end{array}
\end{array}
if (*.f64 (*.f64 y #s(literal 4 binary64)) y) < 9.9999999999999999e-110Initial program 62.4%
Taylor expanded in x around inf
associate--l+N/A
distribute-rgt-out--N/A
metadata-evalN/A
*-commutativeN/A
+-commutativeN/A
unpow2N/A
unpow2N/A
times-fracN/A
associate-*r*N/A
lower-fma.f64N/A
lower-*.f64N/A
lower-/.f64N/A
lower-/.f6486.6
Applied rewrites86.6%
if 9.9999999999999999e-110 < (*.f64 (*.f64 y #s(literal 4 binary64)) y) Initial program 46.3%
Taylor expanded in x around 0
*-lft-identityN/A
associate-*l/N/A
associate-*l*N/A
*-commutativeN/A
lower--.f64N/A
*-commutativeN/A
associate-*l*N/A
associate-*l/N/A
*-lft-identityN/A
unpow2N/A
unpow2N/A
times-fracN/A
associate-*r*N/A
lower-*.f64N/A
lower-*.f64N/A
lower-/.f64N/A
lower-/.f6476.0
Applied rewrites76.0%
Taylor expanded in y around 0
Applied rewrites76.0%
(FPCore (x y) :precision binary64 (if (<= (* (* y 4.0) y) 1e-109) 1.0 (fma (/ 0.5 y) (* x (/ x y)) -1.0)))
double code(double x, double y) {
double tmp;
if (((y * 4.0) * y) <= 1e-109) {
tmp = 1.0;
} else {
tmp = fma((0.5 / y), (x * (x / y)), -1.0);
}
return tmp;
}
function code(x, y) tmp = 0.0 if (Float64(Float64(y * 4.0) * y) <= 1e-109) tmp = 1.0; else tmp = fma(Float64(0.5 / y), Float64(x * Float64(x / y)), -1.0); end return tmp end
code[x_, y_] := If[LessEqual[N[(N[(y * 4.0), $MachinePrecision] * y), $MachinePrecision], 1e-109], 1.0, N[(N[(0.5 / y), $MachinePrecision] * N[(x * N[(x / y), $MachinePrecision]), $MachinePrecision] + -1.0), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\left(y \cdot 4\right) \cdot y \leq 10^{-109}:\\
\;\;\;\;1\\
\mathbf{else}:\\
\;\;\;\;\mathsf{fma}\left(\frac{0.5}{y}, x \cdot \frac{x}{y}, -1\right)\\
\end{array}
\end{array}
if (*.f64 (*.f64 y #s(literal 4 binary64)) y) < 9.9999999999999999e-110Initial program 62.4%
Taylor expanded in x around inf
Applied rewrites85.9%
if 9.9999999999999999e-110 < (*.f64 (*.f64 y #s(literal 4 binary64)) y) Initial program 46.3%
Taylor expanded in x around 0
*-lft-identityN/A
associate-*l/N/A
associate-*l*N/A
*-commutativeN/A
lower--.f64N/A
*-commutativeN/A
associate-*l*N/A
associate-*l/N/A
*-lft-identityN/A
unpow2N/A
unpow2N/A
times-fracN/A
associate-*r*N/A
lower-*.f64N/A
lower-*.f64N/A
lower-/.f64N/A
lower-/.f6476.0
Applied rewrites76.0%
Taylor expanded in y around 0
Applied rewrites76.0%
(FPCore (x y) :precision binary64 (if (<= (* (* y 4.0) y) 3.4e-105) 1.0 -1.0))
double code(double x, double y) {
double tmp;
if (((y * 4.0) * y) <= 3.4e-105) {
tmp = 1.0;
} else {
tmp = -1.0;
}
return tmp;
}
real(8) function code(x, y)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8) :: tmp
if (((y * 4.0d0) * y) <= 3.4d-105) then
tmp = 1.0d0
else
tmp = -1.0d0
end if
code = tmp
end function
public static double code(double x, double y) {
double tmp;
if (((y * 4.0) * y) <= 3.4e-105) {
tmp = 1.0;
} else {
tmp = -1.0;
}
return tmp;
}
def code(x, y): tmp = 0 if ((y * 4.0) * y) <= 3.4e-105: tmp = 1.0 else: tmp = -1.0 return tmp
function code(x, y) tmp = 0.0 if (Float64(Float64(y * 4.0) * y) <= 3.4e-105) tmp = 1.0; else tmp = -1.0; end return tmp end
function tmp_2 = code(x, y) tmp = 0.0; if (((y * 4.0) * y) <= 3.4e-105) tmp = 1.0; else tmp = -1.0; end tmp_2 = tmp; end
code[x_, y_] := If[LessEqual[N[(N[(y * 4.0), $MachinePrecision] * y), $MachinePrecision], 3.4e-105], 1.0, -1.0]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\left(y \cdot 4\right) \cdot y \leq 3.4 \cdot 10^{-105}:\\
\;\;\;\;1\\
\mathbf{else}:\\
\;\;\;\;-1\\
\end{array}
\end{array}
if (*.f64 (*.f64 y #s(literal 4 binary64)) y) < 3.39999999999999992e-105Initial program 62.4%
Taylor expanded in x around inf
Applied rewrites85.9%
if 3.39999999999999992e-105 < (*.f64 (*.f64 y #s(literal 4 binary64)) y) Initial program 46.3%
Taylor expanded in x around 0
Applied rewrites75.2%
(FPCore (x y) :precision binary64 -1.0)
double code(double x, double y) {
return -1.0;
}
real(8) function code(x, y)
real(8), intent (in) :: x
real(8), intent (in) :: y
code = -1.0d0
end function
public static double code(double x, double y) {
return -1.0;
}
def code(x, y): return -1.0
function code(x, y) return -1.0 end
function tmp = code(x, y) tmp = -1.0; end
code[x_, y_] := -1.0
\begin{array}{l}
\\
-1
\end{array}
Initial program 53.1%
Taylor expanded in x around 0
Applied rewrites49.5%
(FPCore (x y)
:precision binary64
(let* ((t_0 (* (* y y) 4.0))
(t_1 (+ (* x x) t_0))
(t_2 (/ t_0 t_1))
(t_3 (* (* y 4.0) y)))
(if (< (/ (- (* x x) t_3) (+ (* x x) t_3)) 0.9743233849626781)
(- (/ (* x x) t_1) t_2)
(- (pow (/ x (sqrt t_1)) 2.0) t_2))))
double code(double x, double y) {
double t_0 = (y * y) * 4.0;
double t_1 = (x * x) + t_0;
double t_2 = t_0 / t_1;
double t_3 = (y * 4.0) * y;
double tmp;
if ((((x * x) - t_3) / ((x * x) + t_3)) < 0.9743233849626781) {
tmp = ((x * x) / t_1) - t_2;
} else {
tmp = pow((x / sqrt(t_1)), 2.0) - t_2;
}
return tmp;
}
real(8) function code(x, y)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8) :: t_0
real(8) :: t_1
real(8) :: t_2
real(8) :: t_3
real(8) :: tmp
t_0 = (y * y) * 4.0d0
t_1 = (x * x) + t_0
t_2 = t_0 / t_1
t_3 = (y * 4.0d0) * y
if ((((x * x) - t_3) / ((x * x) + t_3)) < 0.9743233849626781d0) then
tmp = ((x * x) / t_1) - t_2
else
tmp = ((x / sqrt(t_1)) ** 2.0d0) - t_2
end if
code = tmp
end function
public static double code(double x, double y) {
double t_0 = (y * y) * 4.0;
double t_1 = (x * x) + t_0;
double t_2 = t_0 / t_1;
double t_3 = (y * 4.0) * y;
double tmp;
if ((((x * x) - t_3) / ((x * x) + t_3)) < 0.9743233849626781) {
tmp = ((x * x) / t_1) - t_2;
} else {
tmp = Math.pow((x / Math.sqrt(t_1)), 2.0) - t_2;
}
return tmp;
}
def code(x, y): t_0 = (y * y) * 4.0 t_1 = (x * x) + t_0 t_2 = t_0 / t_1 t_3 = (y * 4.0) * y tmp = 0 if (((x * x) - t_3) / ((x * x) + t_3)) < 0.9743233849626781: tmp = ((x * x) / t_1) - t_2 else: tmp = math.pow((x / math.sqrt(t_1)), 2.0) - t_2 return tmp
function code(x, y) t_0 = Float64(Float64(y * y) * 4.0) t_1 = Float64(Float64(x * x) + t_0) t_2 = Float64(t_0 / t_1) t_3 = Float64(Float64(y * 4.0) * y) tmp = 0.0 if (Float64(Float64(Float64(x * x) - t_3) / Float64(Float64(x * x) + t_3)) < 0.9743233849626781) tmp = Float64(Float64(Float64(x * x) / t_1) - t_2); else tmp = Float64((Float64(x / sqrt(t_1)) ^ 2.0) - t_2); end return tmp end
function tmp_2 = code(x, y) t_0 = (y * y) * 4.0; t_1 = (x * x) + t_0; t_2 = t_0 / t_1; t_3 = (y * 4.0) * y; tmp = 0.0; if ((((x * x) - t_3) / ((x * x) + t_3)) < 0.9743233849626781) tmp = ((x * x) / t_1) - t_2; else tmp = ((x / sqrt(t_1)) ^ 2.0) - t_2; end tmp_2 = tmp; end
code[x_, y_] := Block[{t$95$0 = N[(N[(y * y), $MachinePrecision] * 4.0), $MachinePrecision]}, Block[{t$95$1 = N[(N[(x * x), $MachinePrecision] + t$95$0), $MachinePrecision]}, Block[{t$95$2 = N[(t$95$0 / t$95$1), $MachinePrecision]}, Block[{t$95$3 = N[(N[(y * 4.0), $MachinePrecision] * y), $MachinePrecision]}, If[Less[N[(N[(N[(x * x), $MachinePrecision] - t$95$3), $MachinePrecision] / N[(N[(x * x), $MachinePrecision] + t$95$3), $MachinePrecision]), $MachinePrecision], 0.9743233849626781], N[(N[(N[(x * x), $MachinePrecision] / t$95$1), $MachinePrecision] - t$95$2), $MachinePrecision], N[(N[Power[N[(x / N[Sqrt[t$95$1], $MachinePrecision]), $MachinePrecision], 2.0], $MachinePrecision] - t$95$2), $MachinePrecision]]]]]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left(y \cdot y\right) \cdot 4\\
t_1 := x \cdot x + t\_0\\
t_2 := \frac{t\_0}{t\_1}\\
t_3 := \left(y \cdot 4\right) \cdot y\\
\mathbf{if}\;\frac{x \cdot x - t\_3}{x \cdot x + t\_3} < 0.9743233849626781:\\
\;\;\;\;\frac{x \cdot x}{t\_1} - t\_2\\
\mathbf{else}:\\
\;\;\;\;{\left(\frac{x}{\sqrt{t\_1}}\right)}^{2} - t\_2\\
\end{array}
\end{array}
herbie shell --seed 2024320
(FPCore (x y)
:name "Diagrams.TwoD.Arc:arcBetween from diagrams-lib-1.3.0.3"
:precision binary64
:alt
(! :herbie-platform default (if (< (/ (- (* x x) (* (* y 4) y)) (+ (* x x) (* (* y 4) y))) 9743233849626781/10000000000000000) (- (/ (* x x) (+ (* x x) (* (* y y) 4))) (/ (* (* y y) 4) (+ (* x x) (* (* y y) 4)))) (- (pow (/ x (sqrt (+ (* x x) (* (* y y) 4)))) 2) (/ (* (* y y) 4) (+ (* x x) (* (* y y) 4))))))
(/ (- (* x x) (* (* y 4.0) y)) (+ (* x x) (* (* y 4.0) y))))