
(FPCore (a b c) :precision binary64 (/ (+ (- b) (sqrt (- (* b b) (* 4.0 (* a c))))) (* 2.0 a)))
double code(double a, double b, double c) {
return (-b + sqrt(((b * b) - (4.0 * (a * c))))) / (2.0 * a);
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
code = (-b + sqrt(((b * b) - (4.0d0 * (a * c))))) / (2.0d0 * a)
end function
public static double code(double a, double b, double c) {
return (-b + Math.sqrt(((b * b) - (4.0 * (a * c))))) / (2.0 * a);
}
def code(a, b, c): return (-b + math.sqrt(((b * b) - (4.0 * (a * c))))) / (2.0 * a)
function code(a, b, c) return Float64(Float64(Float64(-b) + sqrt(Float64(Float64(b * b) - Float64(4.0 * Float64(a * c))))) / Float64(2.0 * a)) end
function tmp = code(a, b, c) tmp = (-b + sqrt(((b * b) - (4.0 * (a * c))))) / (2.0 * a); end
code[a_, b_, c_] := N[(N[((-b) + N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(4.0 * N[(a * c), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(2.0 * a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\left(-b\right) + \sqrt{b \cdot b - 4 \cdot \left(a \cdot c\right)}}{2 \cdot a}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 6 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (a b c) :precision binary64 (/ (+ (- b) (sqrt (- (* b b) (* 4.0 (* a c))))) (* 2.0 a)))
double code(double a, double b, double c) {
return (-b + sqrt(((b * b) - (4.0 * (a * c))))) / (2.0 * a);
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
code = (-b + sqrt(((b * b) - (4.0d0 * (a * c))))) / (2.0d0 * a)
end function
public static double code(double a, double b, double c) {
return (-b + Math.sqrt(((b * b) - (4.0 * (a * c))))) / (2.0 * a);
}
def code(a, b, c): return (-b + math.sqrt(((b * b) - (4.0 * (a * c))))) / (2.0 * a)
function code(a, b, c) return Float64(Float64(Float64(-b) + sqrt(Float64(Float64(b * b) - Float64(4.0 * Float64(a * c))))) / Float64(2.0 * a)) end
function tmp = code(a, b, c) tmp = (-b + sqrt(((b * b) - (4.0 * (a * c))))) / (2.0 * a); end
code[a_, b_, c_] := N[(N[((-b) + N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(4.0 * N[(a * c), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / N[(2.0 * a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{\left(-b\right) + \sqrt{b \cdot b - 4 \cdot \left(a \cdot c\right)}}{2 \cdot a}
\end{array}
(FPCore (a b c)
:precision binary64
(if (<= b -1e+155)
(/ (- b) a)
(if (<= b 1.12e-128)
(/ (- (sqrt (- (* b b) (* 4.0 (* a c)))) b) (* a 2.0))
(/ (- c) b))))
double code(double a, double b, double c) {
double tmp;
if (b <= -1e+155) {
tmp = -b / a;
} else if (b <= 1.12e-128) {
tmp = (sqrt(((b * b) - (4.0 * (a * c)))) - b) / (a * 2.0);
} else {
tmp = -c / b;
}
return tmp;
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
real(8) :: tmp
if (b <= (-1d+155)) then
tmp = -b / a
else if (b <= 1.12d-128) then
tmp = (sqrt(((b * b) - (4.0d0 * (a * c)))) - b) / (a * 2.0d0)
else
tmp = -c / b
end if
code = tmp
end function
public static double code(double a, double b, double c) {
double tmp;
if (b <= -1e+155) {
tmp = -b / a;
} else if (b <= 1.12e-128) {
tmp = (Math.sqrt(((b * b) - (4.0 * (a * c)))) - b) / (a * 2.0);
} else {
tmp = -c / b;
}
return tmp;
}
def code(a, b, c): tmp = 0 if b <= -1e+155: tmp = -b / a elif b <= 1.12e-128: tmp = (math.sqrt(((b * b) - (4.0 * (a * c)))) - b) / (a * 2.0) else: tmp = -c / b return tmp
function code(a, b, c) tmp = 0.0 if (b <= -1e+155) tmp = Float64(Float64(-b) / a); elseif (b <= 1.12e-128) tmp = Float64(Float64(sqrt(Float64(Float64(b * b) - Float64(4.0 * Float64(a * c)))) - b) / Float64(a * 2.0)); else tmp = Float64(Float64(-c) / b); end return tmp end
function tmp_2 = code(a, b, c) tmp = 0.0; if (b <= -1e+155) tmp = -b / a; elseif (b <= 1.12e-128) tmp = (sqrt(((b * b) - (4.0 * (a * c)))) - b) / (a * 2.0); else tmp = -c / b; end tmp_2 = tmp; end
code[a_, b_, c_] := If[LessEqual[b, -1e+155], N[((-b) / a), $MachinePrecision], If[LessEqual[b, 1.12e-128], N[(N[(N[Sqrt[N[(N[(b * b), $MachinePrecision] - N[(4.0 * N[(a * c), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] - b), $MachinePrecision] / N[(a * 2.0), $MachinePrecision]), $MachinePrecision], N[((-c) / b), $MachinePrecision]]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;b \leq -1 \cdot 10^{+155}:\\
\;\;\;\;\frac{-b}{a}\\
\mathbf{elif}\;b \leq 1.12 \cdot 10^{-128}:\\
\;\;\;\;\frac{\sqrt{b \cdot b - 4 \cdot \left(a \cdot c\right)} - b}{a \cdot 2}\\
\mathbf{else}:\\
\;\;\;\;\frac{-c}{b}\\
\end{array}
\end{array}
if b < -1.00000000000000001e155Initial program 51.4%
*-commutative51.4%
Simplified51.4%
Taylor expanded in b around -inf 100.0%
associate-*r/100.0%
mul-1-neg100.0%
Simplified100.0%
if -1.00000000000000001e155 < b < 1.12e-128Initial program 85.4%
if 1.12e-128 < b Initial program 17.9%
*-commutative17.9%
Simplified17.9%
Taylor expanded in b around inf 79.5%
associate-*r/79.5%
neg-mul-179.5%
Simplified79.5%
Final simplification85.5%
(FPCore (a b c)
:precision binary64
(if (<= b -7.8e-56)
(- (/ c b) (/ b a))
(if (<= b 4.8e-136)
(/ (- (sqrt (* c (* a -4.0))) b) (* a 2.0))
(/ (- c) b))))
double code(double a, double b, double c) {
double tmp;
if (b <= -7.8e-56) {
tmp = (c / b) - (b / a);
} else if (b <= 4.8e-136) {
tmp = (sqrt((c * (a * -4.0))) - b) / (a * 2.0);
} else {
tmp = -c / b;
}
return tmp;
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
real(8) :: tmp
if (b <= (-7.8d-56)) then
tmp = (c / b) - (b / a)
else if (b <= 4.8d-136) then
tmp = (sqrt((c * (a * (-4.0d0)))) - b) / (a * 2.0d0)
else
tmp = -c / b
end if
code = tmp
end function
public static double code(double a, double b, double c) {
double tmp;
if (b <= -7.8e-56) {
tmp = (c / b) - (b / a);
} else if (b <= 4.8e-136) {
tmp = (Math.sqrt((c * (a * -4.0))) - b) / (a * 2.0);
} else {
tmp = -c / b;
}
return tmp;
}
def code(a, b, c): tmp = 0 if b <= -7.8e-56: tmp = (c / b) - (b / a) elif b <= 4.8e-136: tmp = (math.sqrt((c * (a * -4.0))) - b) / (a * 2.0) else: tmp = -c / b return tmp
function code(a, b, c) tmp = 0.0 if (b <= -7.8e-56) tmp = Float64(Float64(c / b) - Float64(b / a)); elseif (b <= 4.8e-136) tmp = Float64(Float64(sqrt(Float64(c * Float64(a * -4.0))) - b) / Float64(a * 2.0)); else tmp = Float64(Float64(-c) / b); end return tmp end
function tmp_2 = code(a, b, c) tmp = 0.0; if (b <= -7.8e-56) tmp = (c / b) - (b / a); elseif (b <= 4.8e-136) tmp = (sqrt((c * (a * -4.0))) - b) / (a * 2.0); else tmp = -c / b; end tmp_2 = tmp; end
code[a_, b_, c_] := If[LessEqual[b, -7.8e-56], N[(N[(c / b), $MachinePrecision] - N[(b / a), $MachinePrecision]), $MachinePrecision], If[LessEqual[b, 4.8e-136], N[(N[(N[Sqrt[N[(c * N[(a * -4.0), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] - b), $MachinePrecision] / N[(a * 2.0), $MachinePrecision]), $MachinePrecision], N[((-c) / b), $MachinePrecision]]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;b \leq -7.8 \cdot 10^{-56}:\\
\;\;\;\;\frac{c}{b} - \frac{b}{a}\\
\mathbf{elif}\;b \leq 4.8 \cdot 10^{-136}:\\
\;\;\;\;\frac{\sqrt{c \cdot \left(a \cdot -4\right)} - b}{a \cdot 2}\\
\mathbf{else}:\\
\;\;\;\;\frac{-c}{b}\\
\end{array}
\end{array}
if b < -7.8e-56Initial program 72.3%
*-commutative72.3%
Simplified72.3%
Taylor expanded in b around -inf 89.2%
+-commutative89.2%
mul-1-neg89.2%
unsub-neg89.2%
Simplified89.2%
if -7.8e-56 < b < 4.7999999999999997e-136Initial program 81.8%
*-commutative81.8%
Simplified81.8%
Taylor expanded in b around 0 75.0%
associate-*r*75.0%
Simplified75.0%
if 4.7999999999999997e-136 < b Initial program 17.9%
*-commutative17.9%
Simplified17.9%
Taylor expanded in b around inf 79.5%
associate-*r/79.5%
neg-mul-179.5%
Simplified79.5%
Final simplification81.5%
(FPCore (a b c) :precision binary64 (if (<= b -2e-310) (- (/ c b) (/ b a)) (/ (- c) b)))
double code(double a, double b, double c) {
double tmp;
if (b <= -2e-310) {
tmp = (c / b) - (b / a);
} else {
tmp = -c / b;
}
return tmp;
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
real(8) :: tmp
if (b <= (-2d-310)) then
tmp = (c / b) - (b / a)
else
tmp = -c / b
end if
code = tmp
end function
public static double code(double a, double b, double c) {
double tmp;
if (b <= -2e-310) {
tmp = (c / b) - (b / a);
} else {
tmp = -c / b;
}
return tmp;
}
def code(a, b, c): tmp = 0 if b <= -2e-310: tmp = (c / b) - (b / a) else: tmp = -c / b return tmp
function code(a, b, c) tmp = 0.0 if (b <= -2e-310) tmp = Float64(Float64(c / b) - Float64(b / a)); else tmp = Float64(Float64(-c) / b); end return tmp end
function tmp_2 = code(a, b, c) tmp = 0.0; if (b <= -2e-310) tmp = (c / b) - (b / a); else tmp = -c / b; end tmp_2 = tmp; end
code[a_, b_, c_] := If[LessEqual[b, -2e-310], N[(N[(c / b), $MachinePrecision] - N[(b / a), $MachinePrecision]), $MachinePrecision], N[((-c) / b), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;b \leq -2 \cdot 10^{-310}:\\
\;\;\;\;\frac{c}{b} - \frac{b}{a}\\
\mathbf{else}:\\
\;\;\;\;\frac{-c}{b}\\
\end{array}
\end{array}
if b < -1.999999999999994e-310Initial program 74.6%
*-commutative74.6%
Simplified74.6%
Taylor expanded in b around -inf 65.3%
+-commutative65.3%
mul-1-neg65.3%
unsub-neg65.3%
Simplified65.3%
if -1.999999999999994e-310 < b Initial program 33.8%
*-commutative33.8%
Simplified33.8%
Taylor expanded in b around inf 63.0%
associate-*r/63.0%
neg-mul-163.0%
Simplified63.0%
Final simplification64.2%
(FPCore (a b c) :precision binary64 (if (<= b 1.4e-297) (/ (- b) a) (/ (- c) b)))
double code(double a, double b, double c) {
double tmp;
if (b <= 1.4e-297) {
tmp = -b / a;
} else {
tmp = -c / b;
}
return tmp;
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
real(8) :: tmp
if (b <= 1.4d-297) then
tmp = -b / a
else
tmp = -c / b
end if
code = tmp
end function
public static double code(double a, double b, double c) {
double tmp;
if (b <= 1.4e-297) {
tmp = -b / a;
} else {
tmp = -c / b;
}
return tmp;
}
def code(a, b, c): tmp = 0 if b <= 1.4e-297: tmp = -b / a else: tmp = -c / b return tmp
function code(a, b, c) tmp = 0.0 if (b <= 1.4e-297) tmp = Float64(Float64(-b) / a); else tmp = Float64(Float64(-c) / b); end return tmp end
function tmp_2 = code(a, b, c) tmp = 0.0; if (b <= 1.4e-297) tmp = -b / a; else tmp = -c / b; end tmp_2 = tmp; end
code[a_, b_, c_] := If[LessEqual[b, 1.4e-297], N[((-b) / a), $MachinePrecision], N[((-c) / b), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;b \leq 1.4 \cdot 10^{-297}:\\
\;\;\;\;\frac{-b}{a}\\
\mathbf{else}:\\
\;\;\;\;\frac{-c}{b}\\
\end{array}
\end{array}
if b < 1.39999999999999992e-297Initial program 74.8%
*-commutative74.8%
Simplified74.8%
Taylor expanded in b around -inf 64.6%
associate-*r/64.6%
mul-1-neg64.6%
Simplified64.6%
if 1.39999999999999992e-297 < b Initial program 33.2%
*-commutative33.2%
Simplified33.2%
Taylor expanded in b around inf 63.5%
associate-*r/63.5%
neg-mul-163.5%
Simplified63.5%
Final simplification64.0%
(FPCore (a b c) :precision binary64 (/ (- b) a))
double code(double a, double b, double c) {
return -b / a;
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
code = -b / a
end function
public static double code(double a, double b, double c) {
return -b / a;
}
def code(a, b, c): return -b / a
function code(a, b, c) return Float64(Float64(-b) / a) end
function tmp = code(a, b, c) tmp = -b / a; end
code[a_, b_, c_] := N[((-b) / a), $MachinePrecision]
\begin{array}{l}
\\
\frac{-b}{a}
\end{array}
Initial program 54.6%
*-commutative54.6%
Simplified54.6%
Taylor expanded in b around -inf 34.6%
associate-*r/34.6%
mul-1-neg34.6%
Simplified34.6%
Final simplification34.6%
(FPCore (a b c) :precision binary64 (/ b a))
double code(double a, double b, double c) {
return b / a;
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
code = b / a
end function
public static double code(double a, double b, double c) {
return b / a;
}
def code(a, b, c): return b / a
function code(a, b, c) return Float64(b / a) end
function tmp = code(a, b, c) tmp = b / a; end
code[a_, b_, c_] := N[(b / a), $MachinePrecision]
\begin{array}{l}
\\
\frac{b}{a}
\end{array}
Initial program 54.6%
*-commutative54.6%
Simplified54.6%
add-sqr-sqrt53.6%
pow253.6%
pow1/253.6%
sqrt-pow153.6%
fma-neg53.6%
distribute-lft-neg-in53.6%
*-commutative53.6%
associate-*r*53.6%
metadata-eval53.6%
metadata-eval53.6%
Applied egg-rr53.6%
pow-pow54.7%
rem-cbrt-cube27.4%
metadata-eval27.4%
pow1/227.3%
clear-num27.3%
associate-/r/27.3%
*-commutative27.3%
associate-/r*27.3%
metadata-eval27.3%
add-sqr-sqrt21.6%
sqrt-unprod27.3%
sqr-neg27.3%
sqrt-unprod5.8%
add-sqr-sqrt21.7%
rem-cbrt-cube36.9%
fma-udef36.9%
add-sqr-sqrt33.3%
Applied egg-rr28.5%
Taylor expanded in a around 0 2.5%
Final simplification2.5%
(FPCore (a b c)
:precision binary64
(let* ((t_0 (fabs (/ b 2.0)))
(t_1 (* (sqrt (fabs a)) (sqrt (fabs c))))
(t_2
(if (== (copysign a c) a)
(* (sqrt (- t_0 t_1)) (sqrt (+ t_0 t_1)))
(hypot (/ b 2.0) t_1))))
(if (< b 0.0) (/ (- t_2 (/ b 2.0)) a) (/ (- c) (+ (/ b 2.0) t_2)))))
double code(double a, double b, double c) {
double t_0 = fabs((b / 2.0));
double t_1 = sqrt(fabs(a)) * sqrt(fabs(c));
double tmp;
if (copysign(a, c) == a) {
tmp = sqrt((t_0 - t_1)) * sqrt((t_0 + t_1));
} else {
tmp = hypot((b / 2.0), t_1);
}
double t_2 = tmp;
double tmp_1;
if (b < 0.0) {
tmp_1 = (t_2 - (b / 2.0)) / a;
} else {
tmp_1 = -c / ((b / 2.0) + t_2);
}
return tmp_1;
}
public static double code(double a, double b, double c) {
double t_0 = Math.abs((b / 2.0));
double t_1 = Math.sqrt(Math.abs(a)) * Math.sqrt(Math.abs(c));
double tmp;
if (Math.copySign(a, c) == a) {
tmp = Math.sqrt((t_0 - t_1)) * Math.sqrt((t_0 + t_1));
} else {
tmp = Math.hypot((b / 2.0), t_1);
}
double t_2 = tmp;
double tmp_1;
if (b < 0.0) {
tmp_1 = (t_2 - (b / 2.0)) / a;
} else {
tmp_1 = -c / ((b / 2.0) + t_2);
}
return tmp_1;
}
def code(a, b, c): t_0 = math.fabs((b / 2.0)) t_1 = math.sqrt(math.fabs(a)) * math.sqrt(math.fabs(c)) tmp = 0 if math.copysign(a, c) == a: tmp = math.sqrt((t_0 - t_1)) * math.sqrt((t_0 + t_1)) else: tmp = math.hypot((b / 2.0), t_1) t_2 = tmp tmp_1 = 0 if b < 0.0: tmp_1 = (t_2 - (b / 2.0)) / a else: tmp_1 = -c / ((b / 2.0) + t_2) return tmp_1
function code(a, b, c) t_0 = abs(Float64(b / 2.0)) t_1 = Float64(sqrt(abs(a)) * sqrt(abs(c))) tmp = 0.0 if (copysign(a, c) == a) tmp = Float64(sqrt(Float64(t_0 - t_1)) * sqrt(Float64(t_0 + t_1))); else tmp = hypot(Float64(b / 2.0), t_1); end t_2 = tmp tmp_1 = 0.0 if (b < 0.0) tmp_1 = Float64(Float64(t_2 - Float64(b / 2.0)) / a); else tmp_1 = Float64(Float64(-c) / Float64(Float64(b / 2.0) + t_2)); end return tmp_1 end
function tmp_3 = code(a, b, c) t_0 = abs((b / 2.0)); t_1 = sqrt(abs(a)) * sqrt(abs(c)); tmp = 0.0; if ((sign(c) * abs(a)) == a) tmp = sqrt((t_0 - t_1)) * sqrt((t_0 + t_1)); else tmp = hypot((b / 2.0), t_1); end t_2 = tmp; tmp_2 = 0.0; if (b < 0.0) tmp_2 = (t_2 - (b / 2.0)) / a; else tmp_2 = -c / ((b / 2.0) + t_2); end tmp_3 = tmp_2; end
code[a_, b_, c_] := Block[{t$95$0 = N[Abs[N[(b / 2.0), $MachinePrecision]], $MachinePrecision]}, Block[{t$95$1 = N[(N[Sqrt[N[Abs[a], $MachinePrecision]], $MachinePrecision] * N[Sqrt[N[Abs[c], $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, Block[{t$95$2 = If[Equal[N[With[{TMP1 = Abs[a], TMP2 = Sign[c]}, TMP1 * If[TMP2 == 0, 1, TMP2]], $MachinePrecision], a], N[(N[Sqrt[N[(t$95$0 - t$95$1), $MachinePrecision]], $MachinePrecision] * N[Sqrt[N[(t$95$0 + t$95$1), $MachinePrecision]], $MachinePrecision]), $MachinePrecision], N[Sqrt[N[(b / 2.0), $MachinePrecision] ^ 2 + t$95$1 ^ 2], $MachinePrecision]]}, If[Less[b, 0.0], N[(N[(t$95$2 - N[(b / 2.0), $MachinePrecision]), $MachinePrecision] / a), $MachinePrecision], N[((-c) / N[(N[(b / 2.0), $MachinePrecision] + t$95$2), $MachinePrecision]), $MachinePrecision]]]]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \left|\frac{b}{2}\right|\\
t_1 := \sqrt{\left|a\right|} \cdot \sqrt{\left|c\right|}\\
t_2 := \begin{array}{l}
\mathbf{if}\;\mathsf{copysign}\left(a, c\right) = a:\\
\;\;\;\;\sqrt{t_0 - t_1} \cdot \sqrt{t_0 + t_1}\\
\mathbf{else}:\\
\;\;\;\;\mathsf{hypot}\left(\frac{b}{2}, t_1\right)\\
\end{array}\\
\mathbf{if}\;b < 0:\\
\;\;\;\;\frac{t_2 - \frac{b}{2}}{a}\\
\mathbf{else}:\\
\;\;\;\;\frac{-c}{\frac{b}{2} + t_2}\\
\end{array}
\end{array}
herbie shell --seed 2024018
(FPCore (a b c)
:name "quadp (p42, positive)"
:precision binary64
:herbie-expected 10
:herbie-target
(if (< b 0.0) (/ (- (if (== (copysign a c) a) (* (sqrt (- (fabs (/ b 2.0)) (* (sqrt (fabs a)) (sqrt (fabs c))))) (sqrt (+ (fabs (/ b 2.0)) (* (sqrt (fabs a)) (sqrt (fabs c)))))) (hypot (/ b 2.0) (* (sqrt (fabs a)) (sqrt (fabs c))))) (/ b 2.0)) a) (/ (- c) (+ (/ b 2.0) (if (== (copysign a c) a) (* (sqrt (- (fabs (/ b 2.0)) (* (sqrt (fabs a)) (sqrt (fabs c))))) (sqrt (+ (fabs (/ b 2.0)) (* (sqrt (fabs a)) (sqrt (fabs c)))))) (hypot (/ b 2.0) (* (sqrt (fabs a)) (sqrt (fabs c))))))))
(/ (+ (- b) (sqrt (- (* b b) (* 4.0 (* a c))))) (* 2.0 a)))