
(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 5 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 -7.8e+134)
(/ (- b) a)
(if (<= b 1.8e-116)
(/ (- (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 <= -7.8e+134) {
tmp = -b / a;
} else if (b <= 1.8e-116) {
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 <= (-7.8d+134)) then
tmp = -b / a
else if (b <= 1.8d-116) 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 <= -7.8e+134) {
tmp = -b / a;
} else if (b <= 1.8e-116) {
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 <= -7.8e+134: tmp = -b / a elif b <= 1.8e-116: 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 <= -7.8e+134) tmp = Float64(Float64(-b) / a); elseif (b <= 1.8e-116) 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 <= -7.8e+134) tmp = -b / a; elseif (b <= 1.8e-116) 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, -7.8e+134], N[((-b) / a), $MachinePrecision], If[LessEqual[b, 1.8e-116], 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 -7.8 \cdot 10^{+134}:\\
\;\;\;\;\frac{-b}{a}\\
\mathbf{elif}\;b \leq 1.8 \cdot 10^{-116}:\\
\;\;\;\;\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 < -7.79999999999999967e134Initial program 52.4%
*-commutative52.4%
Simplified52.4%
Taylor expanded in b around -inf 93.0%
associate-*r/93.0%
mul-1-neg93.0%
Simplified93.0%
if -7.79999999999999967e134 < b < 1.79999999999999988e-116Initial program 89.1%
if 1.79999999999999988e-116 < b Initial program 17.6%
*-commutative17.6%
Simplified17.6%
Taylor expanded in b around inf 84.4%
associate-*r/84.4%
neg-mul-184.4%
Simplified84.4%
Final simplification87.8%
(FPCore (a b c)
:precision binary64
(if (<= b -1.52e-53)
(/ (- b) a)
(if (<= b 3.5e-116)
(/ (- (sqrt (* a (* c -4.0))) b) (* a 2.0))
(/ (- c) b))))
double code(double a, double b, double c) {
double tmp;
if (b <= -1.52e-53) {
tmp = -b / a;
} else if (b <= 3.5e-116) {
tmp = (sqrt((a * (c * -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 <= (-1.52d-53)) then
tmp = -b / a
else if (b <= 3.5d-116) then
tmp = (sqrt((a * (c * (-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 <= -1.52e-53) {
tmp = -b / a;
} else if (b <= 3.5e-116) {
tmp = (Math.sqrt((a * (c * -4.0))) - b) / (a * 2.0);
} else {
tmp = -c / b;
}
return tmp;
}
def code(a, b, c): tmp = 0 if b <= -1.52e-53: tmp = -b / a elif b <= 3.5e-116: tmp = (math.sqrt((a * (c * -4.0))) - b) / (a * 2.0) else: tmp = -c / b return tmp
function code(a, b, c) tmp = 0.0 if (b <= -1.52e-53) tmp = Float64(Float64(-b) / a); elseif (b <= 3.5e-116) tmp = Float64(Float64(sqrt(Float64(a * Float64(c * -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 <= -1.52e-53) tmp = -b / a; elseif (b <= 3.5e-116) tmp = (sqrt((a * (c * -4.0))) - b) / (a * 2.0); else tmp = -c / b; end tmp_2 = tmp; end
code[a_, b_, c_] := If[LessEqual[b, -1.52e-53], N[((-b) / a), $MachinePrecision], If[LessEqual[b, 3.5e-116], N[(N[(N[Sqrt[N[(a * N[(c * -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 -1.52 \cdot 10^{-53}:\\
\;\;\;\;\frac{-b}{a}\\
\mathbf{elif}\;b \leq 3.5 \cdot 10^{-116}:\\
\;\;\;\;\frac{\sqrt{a \cdot \left(c \cdot -4\right)} - b}{a \cdot 2}\\
\mathbf{else}:\\
\;\;\;\;\frac{-c}{b}\\
\end{array}
\end{array}
if b < -1.5200000000000001e-53Initial program 78.3%
*-commutative78.3%
Simplified78.3%
Taylor expanded in b around -inf 90.5%
associate-*r/90.5%
mul-1-neg90.5%
Simplified90.5%
if -1.5200000000000001e-53 < b < 3.49999999999999984e-116Initial program 80.8%
*-commutative80.8%
Simplified80.8%
Applied egg-rr79.5%
+-commutative79.5%
fma-udef79.5%
associate-+l+79.5%
*-commutative79.5%
*-commutative79.5%
+-commutative79.5%
fma-udef79.5%
unpow279.5%
associate-+l+79.5%
distribute-lft-out79.5%
Simplified79.5%
Taylor expanded in b around 0 77.2%
neg-mul-177.2%
unsub-neg77.2%
distribute-rgt-out77.5%
metadata-eval77.5%
associate-*r*77.5%
Simplified77.5%
if 3.49999999999999984e-116 < b Initial program 17.6%
*-commutative17.6%
Simplified17.6%
Taylor expanded in b around inf 84.4%
associate-*r/84.4%
neg-mul-184.4%
Simplified84.4%
Final simplification84.8%
(FPCore (a b c) :precision binary64 (if (<= b 20000.0) (/ (- b) a) (/ 0.0 a)))
double code(double a, double b, double c) {
double tmp;
if (b <= 20000.0) {
tmp = -b / a;
} else {
tmp = 0.0 / a;
}
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 <= 20000.0d0) then
tmp = -b / a
else
tmp = 0.0d0 / a
end if
code = tmp
end function
public static double code(double a, double b, double c) {
double tmp;
if (b <= 20000.0) {
tmp = -b / a;
} else {
tmp = 0.0 / a;
}
return tmp;
}
def code(a, b, c): tmp = 0 if b <= 20000.0: tmp = -b / a else: tmp = 0.0 / a return tmp
function code(a, b, c) tmp = 0.0 if (b <= 20000.0) tmp = Float64(Float64(-b) / a); else tmp = Float64(0.0 / a); end return tmp end
function tmp_2 = code(a, b, c) tmp = 0.0; if (b <= 20000.0) tmp = -b / a; else tmp = 0.0 / a; end tmp_2 = tmp; end
code[a_, b_, c_] := If[LessEqual[b, 20000.0], N[((-b) / a), $MachinePrecision], N[(0.0 / a), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;b \leq 20000:\\
\;\;\;\;\frac{-b}{a}\\
\mathbf{else}:\\
\;\;\;\;\frac{0}{a}\\
\end{array}
\end{array}
if b < 2e4Initial program 72.8%
*-commutative72.8%
Simplified72.8%
Taylor expanded in b around -inf 48.4%
associate-*r/48.4%
mul-1-neg48.4%
Simplified48.4%
if 2e4 < b Initial program 11.4%
*-commutative11.4%
Simplified11.4%
fma-neg11.4%
*-commutative11.4%
distribute-rgt-neg-in11.4%
*-commutative11.4%
metadata-eval11.4%
associate-*r*11.4%
add-cbrt-cube5.6%
pow35.7%
*-commutative5.7%
associate-*l*5.7%
Applied egg-rr5.7%
clear-num5.7%
inv-pow5.7%
neg-mul-15.7%
fma-def5.7%
unpow35.6%
add-cbrt-cube11.4%
fma-udef11.3%
add-sqr-sqrt9.0%
hypot-def23.8%
*-commutative23.8%
Applied egg-rr23.8%
unpow-123.8%
Simplified23.8%
Taylor expanded in a around 0 25.0%
associate-*r/25.0%
distribute-rgt1-in25.0%
metadata-eval25.0%
mul0-lft25.0%
metadata-eval25.0%
Simplified25.0%
Final simplification41.3%
(FPCore (a b c) :precision binary64 (if (<= b 6e-287) (/ (- b) a) (/ (- c) b)))
double code(double a, double b, double c) {
double tmp;
if (b <= 6e-287) {
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 <= 6d-287) 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 <= 6e-287) {
tmp = -b / a;
} else {
tmp = -c / b;
}
return tmp;
}
def code(a, b, c): tmp = 0 if b <= 6e-287: tmp = -b / a else: tmp = -c / b return tmp
function code(a, b, c) tmp = 0.0 if (b <= 6e-287) 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 <= 6e-287) tmp = -b / a; else tmp = -c / b; end tmp_2 = tmp; end
code[a_, b_, c_] := If[LessEqual[b, 6e-287], N[((-b) / a), $MachinePrecision], N[((-c) / b), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;b \leq 6 \cdot 10^{-287}:\\
\;\;\;\;\frac{-b}{a}\\
\mathbf{else}:\\
\;\;\;\;\frac{-c}{b}\\
\end{array}
\end{array}
if b < 5.99999999999999984e-287Initial program 80.5%
*-commutative80.5%
Simplified80.5%
Taylor expanded in b around -inf 66.4%
associate-*r/66.4%
mul-1-neg66.4%
Simplified66.4%
if 5.99999999999999984e-287 < b Initial program 28.0%
*-commutative28.0%
Simplified28.0%
Taylor expanded in b around inf 71.7%
associate-*r/71.7%
neg-mul-171.7%
Simplified71.7%
Final simplification69.1%
(FPCore (a b c) :precision binary64 (/ 0.0 a))
double code(double a, double b, double c) {
return 0.0 / a;
}
real(8) function code(a, b, c)
real(8), intent (in) :: a
real(8), intent (in) :: b
real(8), intent (in) :: c
code = 0.0d0 / a
end function
public static double code(double a, double b, double c) {
return 0.0 / a;
}
def code(a, b, c): return 0.0 / a
function code(a, b, c) return Float64(0.0 / a) end
function tmp = code(a, b, c) tmp = 0.0 / a; end
code[a_, b_, c_] := N[(0.0 / a), $MachinePrecision]
\begin{array}{l}
\\
\frac{0}{a}
\end{array}
Initial program 54.0%
*-commutative54.0%
Simplified54.0%
fma-neg54.1%
*-commutative54.1%
distribute-rgt-neg-in54.1%
*-commutative54.1%
metadata-eval54.1%
associate-*r*54.1%
add-cbrt-cube31.3%
pow331.3%
*-commutative31.3%
associate-*l*31.3%
Applied egg-rr31.3%
clear-num31.3%
inv-pow31.3%
neg-mul-131.3%
fma-def31.3%
unpow331.3%
add-cbrt-cube53.9%
fma-udef53.9%
add-sqr-sqrt45.2%
hypot-def52.2%
*-commutative52.2%
Applied egg-rr52.2%
unpow-152.2%
Simplified52.2%
Taylor expanded in a around 0 9.6%
associate-*r/9.6%
distribute-rgt1-in9.6%
metadata-eval9.6%
mul0-lft9.6%
metadata-eval9.6%
Simplified9.6%
Final simplification9.6%
(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 2023321
(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)))