
(FPCore (x y z t) :precision binary64 (- x (/ (* (* y 2.0) z) (- (* (* z 2.0) z) (* y t)))))
double code(double x, double y, double z, double t) {
return x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t)));
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
code = x - (((y * 2.0d0) * z) / (((z * 2.0d0) * z) - (y * t)))
end function
public static double code(double x, double y, double z, double t) {
return x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t)));
}
def code(x, y, z, t): return x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t)))
function code(x, y, z, t) return Float64(x - Float64(Float64(Float64(y * 2.0) * z) / Float64(Float64(Float64(z * 2.0) * z) - Float64(y * t)))) end
function tmp = code(x, y, z, t) tmp = x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t))); end
code[x_, y_, z_, t_] := N[(x - N[(N[(N[(y * 2.0), $MachinePrecision] * z), $MachinePrecision] / N[(N[(N[(z * 2.0), $MachinePrecision] * z), $MachinePrecision] - N[(y * t), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
x - \frac{\left(y \cdot 2\right) \cdot z}{\left(z \cdot 2\right) \cdot z - y \cdot t}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 7 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (x y z t) :precision binary64 (- x (/ (* (* y 2.0) z) (- (* (* z 2.0) z) (* y t)))))
double code(double x, double y, double z, double t) {
return x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t)));
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
code = x - (((y * 2.0d0) * z) / (((z * 2.0d0) * z) - (y * t)))
end function
public static double code(double x, double y, double z, double t) {
return x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t)));
}
def code(x, y, z, t): return x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t)))
function code(x, y, z, t) return Float64(x - Float64(Float64(Float64(y * 2.0) * z) / Float64(Float64(Float64(z * 2.0) * z) - Float64(y * t)))) end
function tmp = code(x, y, z, t) tmp = x - (((y * 2.0) * z) / (((z * 2.0) * z) - (y * t))); end
code[x_, y_, z_, t_] := N[(x - N[(N[(N[(y * 2.0), $MachinePrecision] * z), $MachinePrecision] / N[(N[(N[(z * 2.0), $MachinePrecision] * z), $MachinePrecision] - N[(y * t), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
x - \frac{\left(y \cdot 2\right) \cdot z}{\left(z \cdot 2\right) \cdot z - y \cdot t}
\end{array}
(FPCore (x y z t) :precision binary64 (+ x (/ (* y -2.0) (- (* 2.0 z) (* y (/ t z))))))
double code(double x, double y, double z, double t) {
return x + ((y * -2.0) / ((2.0 * z) - (y * (t / z))));
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
code = x + ((y * (-2.0d0)) / ((2.0d0 * z) - (y * (t / z))))
end function
public static double code(double x, double y, double z, double t) {
return x + ((y * -2.0) / ((2.0 * z) - (y * (t / z))));
}
def code(x, y, z, t): return x + ((y * -2.0) / ((2.0 * z) - (y * (t / z))))
function code(x, y, z, t) return Float64(x + Float64(Float64(y * -2.0) / Float64(Float64(2.0 * z) - Float64(y * Float64(t / z))))) end
function tmp = code(x, y, z, t) tmp = x + ((y * -2.0) / ((2.0 * z) - (y * (t / z)))); end
code[x_, y_, z_, t_] := N[(x + N[(N[(y * -2.0), $MachinePrecision] / N[(N[(2.0 * z), $MachinePrecision] - N[(y * N[(t / z), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
x + \frac{y \cdot -2}{2 \cdot z - y \cdot \frac{t}{z}}
\end{array}
Initial program 83.2%
sub-neg83.2%
associate-/l*89.5%
distribute-neg-frac89.5%
distribute-rgt-neg-in89.5%
metadata-eval89.5%
div-sub89.5%
*-commutative89.5%
associate-/l*95.6%
associate-/r/95.6%
*-inverses95.6%
*-lft-identity95.6%
*-commutative95.6%
*-commutative95.6%
associate-/l*97.1%
associate-/r/98.5%
Simplified98.5%
Final simplification98.5%
(FPCore (x y z t) :precision binary64 (if (or (<= z -4.3e-26) (not (<= z 2.3e-34))) (- x (/ y z)) (+ x (* z (/ 2.0 t)))))
double code(double x, double y, double z, double t) {
double tmp;
if ((z <= -4.3e-26) || !(z <= 2.3e-34)) {
tmp = x - (y / z);
} else {
tmp = x + (z * (2.0 / t));
}
return tmp;
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
real(8) :: tmp
if ((z <= (-4.3d-26)) .or. (.not. (z <= 2.3d-34))) then
tmp = x - (y / z)
else
tmp = x + (z * (2.0d0 / t))
end if
code = tmp
end function
public static double code(double x, double y, double z, double t) {
double tmp;
if ((z <= -4.3e-26) || !(z <= 2.3e-34)) {
tmp = x - (y / z);
} else {
tmp = x + (z * (2.0 / t));
}
return tmp;
}
def code(x, y, z, t): tmp = 0 if (z <= -4.3e-26) or not (z <= 2.3e-34): tmp = x - (y / z) else: tmp = x + (z * (2.0 / t)) return tmp
function code(x, y, z, t) tmp = 0.0 if ((z <= -4.3e-26) || !(z <= 2.3e-34)) tmp = Float64(x - Float64(y / z)); else tmp = Float64(x + Float64(z * Float64(2.0 / t))); end return tmp end
function tmp_2 = code(x, y, z, t) tmp = 0.0; if ((z <= -4.3e-26) || ~((z <= 2.3e-34))) tmp = x - (y / z); else tmp = x + (z * (2.0 / t)); end tmp_2 = tmp; end
code[x_, y_, z_, t_] := If[Or[LessEqual[z, -4.3e-26], N[Not[LessEqual[z, 2.3e-34]], $MachinePrecision]], N[(x - N[(y / z), $MachinePrecision]), $MachinePrecision], N[(x + N[(z * N[(2.0 / t), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;z \leq -4.3 \cdot 10^{-26} \lor \neg \left(z \leq 2.3 \cdot 10^{-34}\right):\\
\;\;\;\;x - \frac{y}{z}\\
\mathbf{else}:\\
\;\;\;\;x + z \cdot \frac{2}{t}\\
\end{array}
\end{array}
if z < -4.29999999999999988e-26 or 2.30000000000000011e-34 < z Initial program 77.3%
sub-neg77.3%
associate-*l*76.6%
*-commutative76.6%
associate-/l*87.1%
associate-/r/86.4%
distribute-rgt-neg-in86.4%
*-commutative86.4%
associate-*l*86.4%
fma-neg86.4%
distribute-rgt-neg-in86.4%
metadata-eval86.4%
Simplified86.4%
Taylor expanded in y around 0 87.8%
mul-1-neg87.8%
sub-neg87.8%
Simplified87.8%
if -4.29999999999999988e-26 < z < 2.30000000000000011e-34Initial program 90.3%
sub-neg90.3%
associate-*l*90.3%
*-commutative90.3%
associate-/l*91.4%
associate-/r/92.9%
distribute-rgt-neg-in92.9%
*-commutative92.9%
associate-*l*92.9%
fma-neg92.9%
distribute-rgt-neg-in92.9%
metadata-eval92.9%
Simplified92.9%
Taylor expanded in y around inf 95.2%
associate-*l/95.3%
neg-mul-195.3%
*-commutative95.3%
distribute-lft-neg-in95.3%
metadata-eval95.3%
associate-*r/95.3%
clear-num95.2%
un-div-inv95.2%
Applied egg-rr95.2%
associate-/r/95.2%
Simplified95.2%
Final simplification91.1%
(FPCore (x y z t) :precision binary64 (if (or (<= z -4.5e-26) (not (<= z 2e-34))) (- x (/ y z)) (- x (/ (* -2.0 z) t))))
double code(double x, double y, double z, double t) {
double tmp;
if ((z <= -4.5e-26) || !(z <= 2e-34)) {
tmp = x - (y / z);
} else {
tmp = x - ((-2.0 * z) / t);
}
return tmp;
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
real(8) :: tmp
if ((z <= (-4.5d-26)) .or. (.not. (z <= 2d-34))) then
tmp = x - (y / z)
else
tmp = x - (((-2.0d0) * z) / t)
end if
code = tmp
end function
public static double code(double x, double y, double z, double t) {
double tmp;
if ((z <= -4.5e-26) || !(z <= 2e-34)) {
tmp = x - (y / z);
} else {
tmp = x - ((-2.0 * z) / t);
}
return tmp;
}
def code(x, y, z, t): tmp = 0 if (z <= -4.5e-26) or not (z <= 2e-34): tmp = x - (y / z) else: tmp = x - ((-2.0 * z) / t) return tmp
function code(x, y, z, t) tmp = 0.0 if ((z <= -4.5e-26) || !(z <= 2e-34)) tmp = Float64(x - Float64(y / z)); else tmp = Float64(x - Float64(Float64(-2.0 * z) / t)); end return tmp end
function tmp_2 = code(x, y, z, t) tmp = 0.0; if ((z <= -4.5e-26) || ~((z <= 2e-34))) tmp = x - (y / z); else tmp = x - ((-2.0 * z) / t); end tmp_2 = tmp; end
code[x_, y_, z_, t_] := If[Or[LessEqual[z, -4.5e-26], N[Not[LessEqual[z, 2e-34]], $MachinePrecision]], N[(x - N[(y / z), $MachinePrecision]), $MachinePrecision], N[(x - N[(N[(-2.0 * z), $MachinePrecision] / t), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;z \leq -4.5 \cdot 10^{-26} \lor \neg \left(z \leq 2 \cdot 10^{-34}\right):\\
\;\;\;\;x - \frac{y}{z}\\
\mathbf{else}:\\
\;\;\;\;x - \frac{-2 \cdot z}{t}\\
\end{array}
\end{array}
if z < -4.4999999999999999e-26 or 1.99999999999999986e-34 < z Initial program 77.3%
sub-neg77.3%
associate-*l*76.6%
*-commutative76.6%
associate-/l*87.1%
associate-/r/86.4%
distribute-rgt-neg-in86.4%
*-commutative86.4%
associate-*l*86.4%
fma-neg86.4%
distribute-rgt-neg-in86.4%
metadata-eval86.4%
Simplified86.4%
Taylor expanded in y around 0 87.8%
mul-1-neg87.8%
sub-neg87.8%
Simplified87.8%
if -4.4999999999999999e-26 < z < 1.99999999999999986e-34Initial program 90.3%
Taylor expanded in y around inf 95.3%
associate-*r/95.3%
*-commutative95.3%
Simplified95.3%
Final simplification91.2%
(FPCore (x y z t) :precision binary64 (if (or (<= z -1.55e-50) (not (<= z 1.3e+177))) (- x (/ y z)) x))
double code(double x, double y, double z, double t) {
double tmp;
if ((z <= -1.55e-50) || !(z <= 1.3e+177)) {
tmp = x - (y / z);
} else {
tmp = x;
}
return tmp;
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
real(8) :: tmp
if ((z <= (-1.55d-50)) .or. (.not. (z <= 1.3d+177))) then
tmp = x - (y / z)
else
tmp = x
end if
code = tmp
end function
public static double code(double x, double y, double z, double t) {
double tmp;
if ((z <= -1.55e-50) || !(z <= 1.3e+177)) {
tmp = x - (y / z);
} else {
tmp = x;
}
return tmp;
}
def code(x, y, z, t): tmp = 0 if (z <= -1.55e-50) or not (z <= 1.3e+177): tmp = x - (y / z) else: tmp = x return tmp
function code(x, y, z, t) tmp = 0.0 if ((z <= -1.55e-50) || !(z <= 1.3e+177)) tmp = Float64(x - Float64(y / z)); else tmp = x; end return tmp end
function tmp_2 = code(x, y, z, t) tmp = 0.0; if ((z <= -1.55e-50) || ~((z <= 1.3e+177))) tmp = x - (y / z); else tmp = x; end tmp_2 = tmp; end
code[x_, y_, z_, t_] := If[Or[LessEqual[z, -1.55e-50], N[Not[LessEqual[z, 1.3e+177]], $MachinePrecision]], N[(x - N[(y / z), $MachinePrecision]), $MachinePrecision], x]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;z \leq -1.55 \cdot 10^{-50} \lor \neg \left(z \leq 1.3 \cdot 10^{+177}\right):\\
\;\;\;\;x - \frac{y}{z}\\
\mathbf{else}:\\
\;\;\;\;x\\
\end{array}
\end{array}
if z < -1.5500000000000001e-50 or 1.2999999999999999e177 < z Initial program 70.4%
sub-neg70.4%
associate-*l*69.4%
*-commutative69.4%
associate-/l*82.8%
associate-/r/81.9%
distribute-rgt-neg-in81.9%
*-commutative81.9%
associate-*l*81.9%
fma-neg81.9%
distribute-rgt-neg-in81.9%
metadata-eval81.9%
Simplified81.9%
Taylor expanded in y around 0 89.0%
mul-1-neg89.0%
sub-neg89.0%
Simplified89.0%
if -1.5500000000000001e-50 < z < 1.2999999999999999e177Initial program 92.1%
sub-neg92.1%
associate-*l*92.1%
*-commutative92.1%
associate-/l*93.4%
associate-/r/94.5%
distribute-rgt-neg-in94.5%
*-commutative94.5%
associate-*l*94.5%
fma-neg94.5%
distribute-rgt-neg-in94.5%
metadata-eval94.5%
Simplified94.5%
Taylor expanded in x around inf 76.0%
Final simplification81.4%
(FPCore (x y z t) :precision binary64 (if (<= x -5.7e-260) x (if (<= x 9e-241) (* 2.0 (/ z t)) x)))
double code(double x, double y, double z, double t) {
double tmp;
if (x <= -5.7e-260) {
tmp = x;
} else if (x <= 9e-241) {
tmp = 2.0 * (z / t);
} else {
tmp = x;
}
return tmp;
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
real(8) :: tmp
if (x <= (-5.7d-260)) then
tmp = x
else if (x <= 9d-241) then
tmp = 2.0d0 * (z / t)
else
tmp = x
end if
code = tmp
end function
public static double code(double x, double y, double z, double t) {
double tmp;
if (x <= -5.7e-260) {
tmp = x;
} else if (x <= 9e-241) {
tmp = 2.0 * (z / t);
} else {
tmp = x;
}
return tmp;
}
def code(x, y, z, t): tmp = 0 if x <= -5.7e-260: tmp = x elif x <= 9e-241: tmp = 2.0 * (z / t) else: tmp = x return tmp
function code(x, y, z, t) tmp = 0.0 if (x <= -5.7e-260) tmp = x; elseif (x <= 9e-241) tmp = Float64(2.0 * Float64(z / t)); else tmp = x; end return tmp end
function tmp_2 = code(x, y, z, t) tmp = 0.0; if (x <= -5.7e-260) tmp = x; elseif (x <= 9e-241) tmp = 2.0 * (z / t); else tmp = x; end tmp_2 = tmp; end
code[x_, y_, z_, t_] := If[LessEqual[x, -5.7e-260], x, If[LessEqual[x, 9e-241], N[(2.0 * N[(z / t), $MachinePrecision]), $MachinePrecision], x]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;x \leq -5.7 \cdot 10^{-260}:\\
\;\;\;\;x\\
\mathbf{elif}\;x \leq 9 \cdot 10^{-241}:\\
\;\;\;\;2 \cdot \frac{z}{t}\\
\mathbf{else}:\\
\;\;\;\;x\\
\end{array}
\end{array}
if x < -5.6999999999999998e-260 or 8.9999999999999997e-241 < x Initial program 84.3%
sub-neg84.3%
associate-*l*83.8%
*-commutative83.8%
associate-/l*90.7%
associate-/r/91.0%
distribute-rgt-neg-in91.0%
*-commutative91.0%
associate-*l*91.0%
fma-neg91.0%
distribute-rgt-neg-in91.0%
metadata-eval91.0%
Simplified91.0%
Taylor expanded in x around inf 82.2%
if -5.6999999999999998e-260 < x < 8.9999999999999997e-241Initial program 74.6%
Taylor expanded in y around inf 52.7%
associate-*r/52.7%
*-commutative52.7%
Simplified52.7%
Taylor expanded in x around 0 52.7%
Final simplification79.0%
(FPCore (x y z t) :precision binary64 (if (<= x -1.5e-276) x (if (<= x 2.05e-227) (- (/ y z)) x)))
double code(double x, double y, double z, double t) {
double tmp;
if (x <= -1.5e-276) {
tmp = x;
} else if (x <= 2.05e-227) {
tmp = -(y / z);
} else {
tmp = x;
}
return tmp;
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
real(8) :: tmp
if (x <= (-1.5d-276)) then
tmp = x
else if (x <= 2.05d-227) then
tmp = -(y / z)
else
tmp = x
end if
code = tmp
end function
public static double code(double x, double y, double z, double t) {
double tmp;
if (x <= -1.5e-276) {
tmp = x;
} else if (x <= 2.05e-227) {
tmp = -(y / z);
} else {
tmp = x;
}
return tmp;
}
def code(x, y, z, t): tmp = 0 if x <= -1.5e-276: tmp = x elif x <= 2.05e-227: tmp = -(y / z) else: tmp = x return tmp
function code(x, y, z, t) tmp = 0.0 if (x <= -1.5e-276) tmp = x; elseif (x <= 2.05e-227) tmp = Float64(-Float64(y / z)); else tmp = x; end return tmp end
function tmp_2 = code(x, y, z, t) tmp = 0.0; if (x <= -1.5e-276) tmp = x; elseif (x <= 2.05e-227) tmp = -(y / z); else tmp = x; end tmp_2 = tmp; end
code[x_, y_, z_, t_] := If[LessEqual[x, -1.5e-276], x, If[LessEqual[x, 2.05e-227], (-N[(y / z), $MachinePrecision]), x]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;x \leq -1.5 \cdot 10^{-276}:\\
\;\;\;\;x\\
\mathbf{elif}\;x \leq 2.05 \cdot 10^{-227}:\\
\;\;\;\;-\frac{y}{z}\\
\mathbf{else}:\\
\;\;\;\;x\\
\end{array}
\end{array}
if x < -1.49999999999999994e-276 or 2.05000000000000005e-227 < x Initial program 84.6%
sub-neg84.6%
associate-*l*84.2%
*-commutative84.2%
associate-/l*90.4%
associate-/r/90.7%
distribute-rgt-neg-in90.7%
*-commutative90.7%
associate-*l*90.7%
fma-neg90.7%
distribute-rgt-neg-in90.7%
metadata-eval90.7%
Simplified90.7%
Taylor expanded in x around inf 82.0%
if -1.49999999999999994e-276 < x < 2.05000000000000005e-227Initial program 70.1%
sub-neg70.1%
associate-/l*77.0%
distribute-neg-frac77.0%
distribute-rgt-neg-in77.0%
metadata-eval77.0%
div-sub77.0%
*-commutative77.0%
associate-/l*84.7%
associate-/r/84.7%
*-inverses84.7%
*-lft-identity84.7%
*-commutative84.7%
*-commutative84.7%
associate-/l*88.1%
associate-/r/92.4%
Simplified92.4%
+-commutative92.4%
div-inv92.2%
fma-define92.2%
*-commutative92.2%
Applied egg-rr92.2%
Taylor expanded in z around inf 53.4%
Taylor expanded in y around inf 45.9%
associate-*r/45.9%
neg-mul-145.9%
Simplified45.9%
Final simplification78.5%
(FPCore (x y z t) :precision binary64 x)
double code(double x, double y, double z, double t) {
return x;
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
code = x
end function
public static double code(double x, double y, double z, double t) {
return x;
}
def code(x, y, z, t): return x
function code(x, y, z, t) return x end
function tmp = code(x, y, z, t) tmp = x; end
code[x_, y_, z_, t_] := x
\begin{array}{l}
\\
x
\end{array}
Initial program 83.2%
sub-neg83.2%
associate-*l*82.8%
*-commutative82.8%
associate-/l*89.1%
associate-/r/89.3%
distribute-rgt-neg-in89.3%
*-commutative89.3%
associate-*l*89.3%
fma-neg89.3%
distribute-rgt-neg-in89.3%
metadata-eval89.3%
Simplified89.3%
Taylor expanded in x around inf 75.2%
Final simplification75.2%
(FPCore (x y z t) :precision binary64 (- x (/ 1.0 (- (/ z y) (/ (/ t 2.0) z)))))
double code(double x, double y, double z, double t) {
return x - (1.0 / ((z / y) - ((t / 2.0) / z)));
}
real(8) function code(x, y, z, t)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
code = x - (1.0d0 / ((z / y) - ((t / 2.0d0) / z)))
end function
public static double code(double x, double y, double z, double t) {
return x - (1.0 / ((z / y) - ((t / 2.0) / z)));
}
def code(x, y, z, t): return x - (1.0 / ((z / y) - ((t / 2.0) / z)))
function code(x, y, z, t) return Float64(x - Float64(1.0 / Float64(Float64(z / y) - Float64(Float64(t / 2.0) / z)))) end
function tmp = code(x, y, z, t) tmp = x - (1.0 / ((z / y) - ((t / 2.0) / z))); end
code[x_, y_, z_, t_] := N[(x - N[(1.0 / N[(N[(z / y), $MachinePrecision] - N[(N[(t / 2.0), $MachinePrecision] / z), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
x - \frac{1}{\frac{z}{y} - \frac{\frac{t}{2}}{z}}
\end{array}
herbie shell --seed 2024034
(FPCore (x y z t)
:name "Numeric.AD.Rank1.Halley:findZero from ad-4.2.4"
:precision binary64
:herbie-target
(- x (/ 1.0 (- (/ z y) (/ (/ t 2.0) z))))
(- x (/ (* (* y 2.0) z) (- (* (* z 2.0) z) (* y t)))))