
(FPCore (a b_2 c) :precision binary64 (/ (- (- b_2) (sqrt (- (* b_2 b_2) (* a c)))) a))
double code(double a, double b_2, double c) {
return (-b_2 - sqrt(((b_2 * b_2) - (a * c)))) / a;
}
real(8) function code(a, b_2, c)
real(8), intent (in) :: a
real(8), intent (in) :: b_2
real(8), intent (in) :: c
code = (-b_2 - sqrt(((b_2 * b_2) - (a * c)))) / a
end function
public static double code(double a, double b_2, double c) {
return (-b_2 - Math.sqrt(((b_2 * b_2) - (a * c)))) / a;
}
def code(a, b_2, c): return (-b_2 - math.sqrt(((b_2 * b_2) - (a * c)))) / a
function code(a, b_2, c) return Float64(Float64(Float64(-b_2) - sqrt(Float64(Float64(b_2 * b_2) - Float64(a * c)))) / a) end
function tmp = code(a, b_2, c) tmp = (-b_2 - sqrt(((b_2 * b_2) - (a * c)))) / a; end
code[a_, b$95$2_, c_] := N[(N[((-b$95$2) - N[Sqrt[N[(N[(b$95$2 * b$95$2), $MachinePrecision] - N[(a * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / a), $MachinePrecision]
\begin{array}{l}
\\
\frac{\left(-b\_2\right) - \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 7 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (a b_2 c) :precision binary64 (/ (- (- b_2) (sqrt (- (* b_2 b_2) (* a c)))) a))
double code(double a, double b_2, double c) {
return (-b_2 - sqrt(((b_2 * b_2) - (a * c)))) / a;
}
real(8) function code(a, b_2, c)
real(8), intent (in) :: a
real(8), intent (in) :: b_2
real(8), intent (in) :: c
code = (-b_2 - sqrt(((b_2 * b_2) - (a * c)))) / a
end function
public static double code(double a, double b_2, double c) {
return (-b_2 - Math.sqrt(((b_2 * b_2) - (a * c)))) / a;
}
def code(a, b_2, c): return (-b_2 - math.sqrt(((b_2 * b_2) - (a * c)))) / a
function code(a, b_2, c) return Float64(Float64(Float64(-b_2) - sqrt(Float64(Float64(b_2 * b_2) - Float64(a * c)))) / a) end
function tmp = code(a, b_2, c) tmp = (-b_2 - sqrt(((b_2 * b_2) - (a * c)))) / a; end
code[a_, b$95$2_, c_] := N[(N[((-b$95$2) - N[Sqrt[N[(N[(b$95$2 * b$95$2), $MachinePrecision] - N[(a * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / a), $MachinePrecision]
\begin{array}{l}
\\
\frac{\left(-b\_2\right) - \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a}
\end{array}
(FPCore (a b_2 c)
:precision binary64
(if (<= b_2 -1.45e-30)
(/ (* c -0.5) b_2)
(if (<= b_2 2e+84)
(/ (- (- b_2) (sqrt (- (* b_2 b_2) (* a c)))) a)
(/ (* b_2 -2.0) a))))
double code(double a, double b_2, double c) {
double tmp;
if (b_2 <= -1.45e-30) {
tmp = (c * -0.5) / b_2;
} else if (b_2 <= 2e+84) {
tmp = (-b_2 - sqrt(((b_2 * b_2) - (a * c)))) / a;
} else {
tmp = (b_2 * -2.0) / a;
}
return tmp;
}
real(8) function code(a, b_2, c)
real(8), intent (in) :: a
real(8), intent (in) :: b_2
real(8), intent (in) :: c
real(8) :: tmp
if (b_2 <= (-1.45d-30)) then
tmp = (c * (-0.5d0)) / b_2
else if (b_2 <= 2d+84) then
tmp = (-b_2 - sqrt(((b_2 * b_2) - (a * c)))) / a
else
tmp = (b_2 * (-2.0d0)) / a
end if
code = tmp
end function
public static double code(double a, double b_2, double c) {
double tmp;
if (b_2 <= -1.45e-30) {
tmp = (c * -0.5) / b_2;
} else if (b_2 <= 2e+84) {
tmp = (-b_2 - Math.sqrt(((b_2 * b_2) - (a * c)))) / a;
} else {
tmp = (b_2 * -2.0) / a;
}
return tmp;
}
def code(a, b_2, c): tmp = 0 if b_2 <= -1.45e-30: tmp = (c * -0.5) / b_2 elif b_2 <= 2e+84: tmp = (-b_2 - math.sqrt(((b_2 * b_2) - (a * c)))) / a else: tmp = (b_2 * -2.0) / a return tmp
function code(a, b_2, c) tmp = 0.0 if (b_2 <= -1.45e-30) tmp = Float64(Float64(c * -0.5) / b_2); elseif (b_2 <= 2e+84) tmp = Float64(Float64(Float64(-b_2) - sqrt(Float64(Float64(b_2 * b_2) - Float64(a * c)))) / a); else tmp = Float64(Float64(b_2 * -2.0) / a); end return tmp end
function tmp_2 = code(a, b_2, c) tmp = 0.0; if (b_2 <= -1.45e-30) tmp = (c * -0.5) / b_2; elseif (b_2 <= 2e+84) tmp = (-b_2 - sqrt(((b_2 * b_2) - (a * c)))) / a; else tmp = (b_2 * -2.0) / a; end tmp_2 = tmp; end
code[a_, b$95$2_, c_] := If[LessEqual[b$95$2, -1.45e-30], N[(N[(c * -0.5), $MachinePrecision] / b$95$2), $MachinePrecision], If[LessEqual[b$95$2, 2e+84], N[(N[((-b$95$2) - N[Sqrt[N[(N[(b$95$2 * b$95$2), $MachinePrecision] - N[(a * c), $MachinePrecision]), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / a), $MachinePrecision], N[(N[(b$95$2 * -2.0), $MachinePrecision] / a), $MachinePrecision]]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;b\_2 \leq -1.45 \cdot 10^{-30}:\\
\;\;\;\;\frac{c \cdot -0.5}{b\_2}\\
\mathbf{elif}\;b\_2 \leq 2 \cdot 10^{+84}:\\
\;\;\;\;\frac{\left(-b\_2\right) - \sqrt{b\_2 \cdot b\_2 - a \cdot c}}{a}\\
\mathbf{else}:\\
\;\;\;\;\frac{b\_2 \cdot -2}{a}\\
\end{array}
\end{array}
if b_2 < -1.44999999999999995e-30Initial program 8.9%
Taylor expanded in b_2 around -inf
associate-*r/N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f6491.5
Applied rewrites91.5%
if -1.44999999999999995e-30 < b_2 < 2.00000000000000012e84Initial program 79.1%
if 2.00000000000000012e84 < b_2 Initial program 63.7%
Taylor expanded in b_2 around inf
*-commutativeN/A
lower-*.f6498.4
Applied rewrites98.4%
(FPCore (a b_2 c)
:precision binary64
(if (<= b_2 -1.45e-30)
(/ (* c -0.5) b_2)
(if (<= b_2 2.1e-37)
(/ (- (- b_2) (sqrt (* a (- c)))) a)
(fma 0.5 (/ c b_2) (/ (* b_2 -2.0) a)))))
double code(double a, double b_2, double c) {
double tmp;
if (b_2 <= -1.45e-30) {
tmp = (c * -0.5) / b_2;
} else if (b_2 <= 2.1e-37) {
tmp = (-b_2 - sqrt((a * -c))) / a;
} else {
tmp = fma(0.5, (c / b_2), ((b_2 * -2.0) / a));
}
return tmp;
}
function code(a, b_2, c) tmp = 0.0 if (b_2 <= -1.45e-30) tmp = Float64(Float64(c * -0.5) / b_2); elseif (b_2 <= 2.1e-37) tmp = Float64(Float64(Float64(-b_2) - sqrt(Float64(a * Float64(-c)))) / a); else tmp = fma(0.5, Float64(c / b_2), Float64(Float64(b_2 * -2.0) / a)); end return tmp end
code[a_, b$95$2_, c_] := If[LessEqual[b$95$2, -1.45e-30], N[(N[(c * -0.5), $MachinePrecision] / b$95$2), $MachinePrecision], If[LessEqual[b$95$2, 2.1e-37], N[(N[((-b$95$2) - N[Sqrt[N[(a * (-c)), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / a), $MachinePrecision], N[(0.5 * N[(c / b$95$2), $MachinePrecision] + N[(N[(b$95$2 * -2.0), $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision]]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;b\_2 \leq -1.45 \cdot 10^{-30}:\\
\;\;\;\;\frac{c \cdot -0.5}{b\_2}\\
\mathbf{elif}\;b\_2 \leq 2.1 \cdot 10^{-37}:\\
\;\;\;\;\frac{\left(-b\_2\right) - \sqrt{a \cdot \left(-c\right)}}{a}\\
\mathbf{else}:\\
\;\;\;\;\mathsf{fma}\left(0.5, \frac{c}{b\_2}, \frac{b\_2 \cdot -2}{a}\right)\\
\end{array}
\end{array}
if b_2 < -1.44999999999999995e-30Initial program 16.1%
Taylor expanded in b_2 around -inf
associate-*r/N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f6489.8
Applied rewrites89.8%
if -1.44999999999999995e-30 < b_2 < 2.1000000000000001e-37Initial program 73.7%
Taylor expanded in b_2 around 0
associate-*r*N/A
*-commutativeN/A
lower-*.f64N/A
mul-1-negN/A
lower-neg.f6464.5
Applied rewrites64.5%
if 2.1000000000000001e-37 < b_2 Initial program 69.3%
Taylor expanded in b_2 around inf
associate-*r/N/A
*-commutativeN/A
associate-/l*N/A
metadata-evalN/A
distribute-neg-fracN/A
metadata-evalN/A
associate-*r/N/A
lower-*.f64N/A
associate-*r/N/A
metadata-evalN/A
distribute-neg-fracN/A
metadata-evalN/A
lower-/.f6488.3
Applied rewrites88.3%
Taylor expanded in c around 0
+-commutativeN/A
lower-fma.f64N/A
lower-/.f64N/A
associate-*r/N/A
lower-/.f64N/A
lower-*.f6488.9
Applied rewrites88.9%
Final simplification81.1%
(FPCore (a b_2 c)
:precision binary64
(let* ((t_0 (* (sqrt (fabs a)) (sqrt (fabs c))))
(t_1
(if (== (copysign a c) a)
(* (sqrt (- (fabs b_2) t_0)) (sqrt (+ (fabs b_2) t_0)))
(hypot b_2 t_0))))
(if (< b_2 0.0) (/ c (- t_1 b_2)) (/ (+ b_2 t_1) (- a)))))
double code(double a, double b_2, double c) {
double t_0 = sqrt(fabs(a)) * sqrt(fabs(c));
double tmp;
if (copysign(a, c) == a) {
tmp = sqrt((fabs(b_2) - t_0)) * sqrt((fabs(b_2) + t_0));
} else {
tmp = hypot(b_2, t_0);
}
double t_1 = tmp;
double tmp_1;
if (b_2 < 0.0) {
tmp_1 = c / (t_1 - b_2);
} else {
tmp_1 = (b_2 + t_1) / -a;
}
return tmp_1;
}
public static double code(double a, double b_2, double c) {
double t_0 = Math.sqrt(Math.abs(a)) * Math.sqrt(Math.abs(c));
double tmp;
if (Math.copySign(a, c) == a) {
tmp = Math.sqrt((Math.abs(b_2) - t_0)) * Math.sqrt((Math.abs(b_2) + t_0));
} else {
tmp = Math.hypot(b_2, t_0);
}
double t_1 = tmp;
double tmp_1;
if (b_2 < 0.0) {
tmp_1 = c / (t_1 - b_2);
} else {
tmp_1 = (b_2 + t_1) / -a;
}
return tmp_1;
}
def code(a, b_2, c): t_0 = math.sqrt(math.fabs(a)) * math.sqrt(math.fabs(c)) tmp = 0 if math.copysign(a, c) == a: tmp = math.sqrt((math.fabs(b_2) - t_0)) * math.sqrt((math.fabs(b_2) + t_0)) else: tmp = math.hypot(b_2, t_0) t_1 = tmp tmp_1 = 0 if b_2 < 0.0: tmp_1 = c / (t_1 - b_2) else: tmp_1 = (b_2 + t_1) / -a return tmp_1
function code(a, b_2, c) t_0 = Float64(sqrt(abs(a)) * sqrt(abs(c))) tmp = 0.0 if (copysign(a, c) == a) tmp = Float64(sqrt(Float64(abs(b_2) - t_0)) * sqrt(Float64(abs(b_2) + t_0))); else tmp = hypot(b_2, t_0); end t_1 = tmp tmp_1 = 0.0 if (b_2 < 0.0) tmp_1 = Float64(c / Float64(t_1 - b_2)); else tmp_1 = Float64(Float64(b_2 + t_1) / Float64(-a)); end return tmp_1 end
function tmp_3 = code(a, b_2, c) t_0 = sqrt(abs(a)) * sqrt(abs(c)); tmp = 0.0; if ((sign(c) * abs(a)) == a) tmp = sqrt((abs(b_2) - t_0)) * sqrt((abs(b_2) + t_0)); else tmp = hypot(b_2, t_0); end t_1 = tmp; tmp_2 = 0.0; if (b_2 < 0.0) tmp_2 = c / (t_1 - b_2); else tmp_2 = (b_2 + t_1) / -a; end tmp_3 = tmp_2; end
code[a_, b$95$2_, c_] := Block[{t$95$0 = N[(N[Sqrt[N[Abs[a], $MachinePrecision]], $MachinePrecision] * N[Sqrt[N[Abs[c], $MachinePrecision]], $MachinePrecision]), $MachinePrecision]}, Block[{t$95$1 = If[Equal[N[With[{TMP1 = Abs[a], TMP2 = Sign[c]}, TMP1 * If[TMP2 == 0, 1, TMP2]], $MachinePrecision], a], N[(N[Sqrt[N[(N[Abs[b$95$2], $MachinePrecision] - t$95$0), $MachinePrecision]], $MachinePrecision] * N[Sqrt[N[(N[Abs[b$95$2], $MachinePrecision] + t$95$0), $MachinePrecision]], $MachinePrecision]), $MachinePrecision], N[Sqrt[b$95$2 ^ 2 + t$95$0 ^ 2], $MachinePrecision]]}, If[Less[b$95$2, 0.0], N[(c / N[(t$95$1 - b$95$2), $MachinePrecision]), $MachinePrecision], N[(N[(b$95$2 + t$95$1), $MachinePrecision] / (-a)), $MachinePrecision]]]]
\begin{array}{l}
\\
\begin{array}{l}
t_0 := \sqrt{\left|a\right|} \cdot \sqrt{\left|c\right|}\\
t_1 := \begin{array}{l}
\mathbf{if}\;\mathsf{copysign}\left(a, c\right) = a:\\
\;\;\;\;\sqrt{\left|b\_2\right| - t\_0} \cdot \sqrt{\left|b\_2\right| + t\_0}\\
\mathbf{else}:\\
\;\;\;\;\mathsf{hypot}\left(b\_2, t\_0\right)\\
\end{array}\\
\mathbf{if}\;b\_2 < 0:\\
\;\;\;\;\frac{c}{t\_1 - b\_2}\\
\mathbf{else}:\\
\;\;\;\;\frac{b\_2 + t\_1}{-a}\\
\end{array}
\end{array}
herbie shell --seed 2024230
(FPCore (a b_2 c)
:name "quad2m (problem 3.2.1, negative)"
:precision binary64
:herbie-expected 10
:alt
(! :herbie-platform default (let ((sqtD (let ((x (* (sqrt (fabs a)) (sqrt (fabs c))))) (if (== (copysign a c) a) (* (sqrt (- (fabs b_2) x)) (sqrt (+ (fabs b_2) x))) (hypot b_2 x))))) (if (< b_2 0) (/ c (- sqtD b_2)) (/ (+ b_2 sqtD) (- a)))))
(/ (- (- b_2) (sqrt (- (* b_2 b_2) (* a c)))) a))