
(FPCore (x y z t) :precision binary64 (/ x (- y (* z t))))
double code(double x, double y, double z, double t) {
return x / (y - (z * 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 - (z * t))
end function
public static double code(double x, double y, double z, double t) {
return x / (y - (z * t));
}
def code(x, y, z, t): return x / (y - (z * t))
function code(x, y, z, t) return Float64(x / Float64(y - Float64(z * t))) end
function tmp = code(x, y, z, t) tmp = x / (y - (z * t)); end
code[x_, y_, z_, t_] := N[(x / N[(y - N[(z * t), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{x}{y - z \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 (* z t))))
double code(double x, double y, double z, double t) {
return x / (y - (z * 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 - (z * t))
end function
public static double code(double x, double y, double z, double t) {
return x / (y - (z * t));
}
def code(x, y, z, t): return x / (y - (z * t))
function code(x, y, z, t) return Float64(x / Float64(y - Float64(z * t))) end
function tmp = code(x, y, z, t) tmp = x / (y - (z * t)); end
code[x_, y_, z_, t_] := N[(x / N[(y - N[(z * t), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
\frac{x}{y - z \cdot t}
\end{array}
(FPCore (x y z t) :precision binary64 (if (<= (* z t) -1e+250) (/ -1.0 (* z (/ t x))) (/ x (fma z (- t) y))))
double code(double x, double y, double z, double t) {
double tmp;
if ((z * t) <= -1e+250) {
tmp = -1.0 / (z * (t / x));
} else {
tmp = x / fma(z, -t, y);
}
return tmp;
}
function code(x, y, z, t) tmp = 0.0 if (Float64(z * t) <= -1e+250) tmp = Float64(-1.0 / Float64(z * Float64(t / x))); else tmp = Float64(x / fma(z, Float64(-t), y)); end return tmp end
code[x_, y_, z_, t_] := If[LessEqual[N[(z * t), $MachinePrecision], -1e+250], N[(-1.0 / N[(z * N[(t / x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(x / N[(z * (-t) + y), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;z \cdot t \leq -1 \cdot 10^{+250}:\\
\;\;\;\;\frac{-1}{z \cdot \frac{t}{x}}\\
\mathbf{else}:\\
\;\;\;\;\frac{x}{\mathsf{fma}\left(z, -t, y\right)}\\
\end{array}
\end{array}
if (*.f64 z t) < -9.9999999999999992e249Initial program 72.8%
Taylor expanded in y around 0 72.8%
associate-*r/72.8%
neg-mul-172.8%
Simplified72.8%
neg-mul-172.8%
times-frac99.6%
Applied egg-rr99.6%
*-commutative99.6%
frac-times72.8%
*-commutative72.8%
frac-times99.7%
clear-num99.6%
frac-times99.9%
metadata-eval99.9%
Applied egg-rr99.9%
if -9.9999999999999992e249 < (*.f64 z t) Initial program 98.5%
cancel-sign-sub-inv98.5%
+-commutative98.5%
distribute-lft-neg-out98.5%
distribute-rgt-neg-out98.5%
fma-def98.5%
Simplified98.5%
Final simplification98.7%
(FPCore (x y z t)
:precision binary64
(let* ((t_1 (/ (/ (- x) t) z)))
(if (<= (* z t) (- INFINITY))
t_1
(if (<= (* z t) -5e+25)
(/ (- x) (* z t))
(if (<= (* z t) 4e+15) (/ x y) t_1)))))
double code(double x, double y, double z, double t) {
double t_1 = (-x / t) / z;
double tmp;
if ((z * t) <= -((double) INFINITY)) {
tmp = t_1;
} else if ((z * t) <= -5e+25) {
tmp = -x / (z * t);
} else if ((z * t) <= 4e+15) {
tmp = x / y;
} else {
tmp = t_1;
}
return tmp;
}
public static double code(double x, double y, double z, double t) {
double t_1 = (-x / t) / z;
double tmp;
if ((z * t) <= -Double.POSITIVE_INFINITY) {
tmp = t_1;
} else if ((z * t) <= -5e+25) {
tmp = -x / (z * t);
} else if ((z * t) <= 4e+15) {
tmp = x / y;
} else {
tmp = t_1;
}
return tmp;
}
def code(x, y, z, t): t_1 = (-x / t) / z tmp = 0 if (z * t) <= -math.inf: tmp = t_1 elif (z * t) <= -5e+25: tmp = -x / (z * t) elif (z * t) <= 4e+15: tmp = x / y else: tmp = t_1 return tmp
function code(x, y, z, t) t_1 = Float64(Float64(Float64(-x) / t) / z) tmp = 0.0 if (Float64(z * t) <= Float64(-Inf)) tmp = t_1; elseif (Float64(z * t) <= -5e+25) tmp = Float64(Float64(-x) / Float64(z * t)); elseif (Float64(z * t) <= 4e+15) tmp = Float64(x / y); else tmp = t_1; end return tmp end
function tmp_2 = code(x, y, z, t) t_1 = (-x / t) / z; tmp = 0.0; if ((z * t) <= -Inf) tmp = t_1; elseif ((z * t) <= -5e+25) tmp = -x / (z * t); elseif ((z * t) <= 4e+15) tmp = x / y; else tmp = t_1; end tmp_2 = tmp; end
code[x_, y_, z_, t_] := Block[{t$95$1 = N[(N[((-x) / t), $MachinePrecision] / z), $MachinePrecision]}, If[LessEqual[N[(z * t), $MachinePrecision], (-Infinity)], t$95$1, If[LessEqual[N[(z * t), $MachinePrecision], -5e+25], N[((-x) / N[(z * t), $MachinePrecision]), $MachinePrecision], If[LessEqual[N[(z * t), $MachinePrecision], 4e+15], N[(x / y), $MachinePrecision], t$95$1]]]]
\begin{array}{l}
\\
\begin{array}{l}
t_1 := \frac{\frac{-x}{t}}{z}\\
\mathbf{if}\;z \cdot t \leq -\infty:\\
\;\;\;\;t_1\\
\mathbf{elif}\;z \cdot t \leq -5 \cdot 10^{+25}:\\
\;\;\;\;\frac{-x}{z \cdot t}\\
\mathbf{elif}\;z \cdot t \leq 4 \cdot 10^{+15}:\\
\;\;\;\;\frac{x}{y}\\
\mathbf{else}:\\
\;\;\;\;t_1\\
\end{array}
\end{array}
if (*.f64 z t) < -inf.0 or 4e15 < (*.f64 z t) Initial program 87.8%
Taylor expanded in y around 0 78.6%
mul-1-neg78.6%
associate-/r*89.4%
distribute-neg-frac89.4%
Simplified89.4%
if -inf.0 < (*.f64 z t) < -5.00000000000000024e25Initial program 99.7%
Taylor expanded in y around 0 81.0%
associate-*r/81.0%
neg-mul-181.0%
Simplified81.0%
if -5.00000000000000024e25 < (*.f64 z t) < 4e15Initial program 99.9%
Taylor expanded in y around inf 82.2%
Final simplification84.0%
(FPCore (x y z t) :precision binary64 (if (or (<= (* z t) -5e+25) (not (<= (* z t) 4e+15))) (/ (- x) (* z t)) (/ x y)))
double code(double x, double y, double z, double t) {
double tmp;
if (((z * t) <= -5e+25) || !((z * t) <= 4e+15)) {
tmp = -x / (z * t);
} else {
tmp = x / y;
}
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 * t) <= (-5d+25)) .or. (.not. ((z * t) <= 4d+15))) then
tmp = -x / (z * t)
else
tmp = x / y
end if
code = tmp
end function
public static double code(double x, double y, double z, double t) {
double tmp;
if (((z * t) <= -5e+25) || !((z * t) <= 4e+15)) {
tmp = -x / (z * t);
} else {
tmp = x / y;
}
return tmp;
}
def code(x, y, z, t): tmp = 0 if ((z * t) <= -5e+25) or not ((z * t) <= 4e+15): tmp = -x / (z * t) else: tmp = x / y return tmp
function code(x, y, z, t) tmp = 0.0 if ((Float64(z * t) <= -5e+25) || !(Float64(z * t) <= 4e+15)) tmp = Float64(Float64(-x) / Float64(z * t)); else tmp = Float64(x / y); end return tmp end
function tmp_2 = code(x, y, z, t) tmp = 0.0; if (((z * t) <= -5e+25) || ~(((z * t) <= 4e+15))) tmp = -x / (z * t); else tmp = x / y; end tmp_2 = tmp; end
code[x_, y_, z_, t_] := If[Or[LessEqual[N[(z * t), $MachinePrecision], -5e+25], N[Not[LessEqual[N[(z * t), $MachinePrecision], 4e+15]], $MachinePrecision]], N[((-x) / N[(z * t), $MachinePrecision]), $MachinePrecision], N[(x / y), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;z \cdot t \leq -5 \cdot 10^{+25} \lor \neg \left(z \cdot t \leq 4 \cdot 10^{+15}\right):\\
\;\;\;\;\frac{-x}{z \cdot t}\\
\mathbf{else}:\\
\;\;\;\;\frac{x}{y}\\
\end{array}
\end{array}
if (*.f64 z t) < -5.00000000000000024e25 or 4e15 < (*.f64 z t) Initial program 92.6%
Taylor expanded in y around 0 79.5%
associate-*r/79.5%
neg-mul-179.5%
Simplified79.5%
if -5.00000000000000024e25 < (*.f64 z t) < 4e15Initial program 99.9%
Taylor expanded in y around inf 82.2%
Final simplification80.9%
(FPCore (x y z t) :precision binary64 (if (<= (* z t) -5e+25) (/ (/ (- x) z) t) (if (<= (* z t) 4e+15) (/ x y) (/ (/ (- x) t) z))))
double code(double x, double y, double z, double t) {
double tmp;
if ((z * t) <= -5e+25) {
tmp = (-x / z) / t;
} else if ((z * t) <= 4e+15) {
tmp = x / y;
} else {
tmp = (-x / t) / z;
}
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 * t) <= (-5d+25)) then
tmp = (-x / z) / t
else if ((z * t) <= 4d+15) then
tmp = x / y
else
tmp = (-x / t) / z
end if
code = tmp
end function
public static double code(double x, double y, double z, double t) {
double tmp;
if ((z * t) <= -5e+25) {
tmp = (-x / z) / t;
} else if ((z * t) <= 4e+15) {
tmp = x / y;
} else {
tmp = (-x / t) / z;
}
return tmp;
}
def code(x, y, z, t): tmp = 0 if (z * t) <= -5e+25: tmp = (-x / z) / t elif (z * t) <= 4e+15: tmp = x / y else: tmp = (-x / t) / z return tmp
function code(x, y, z, t) tmp = 0.0 if (Float64(z * t) <= -5e+25) tmp = Float64(Float64(Float64(-x) / z) / t); elseif (Float64(z * t) <= 4e+15) tmp = Float64(x / y); else tmp = Float64(Float64(Float64(-x) / t) / z); end return tmp end
function tmp_2 = code(x, y, z, t) tmp = 0.0; if ((z * t) <= -5e+25) tmp = (-x / z) / t; elseif ((z * t) <= 4e+15) tmp = x / y; else tmp = (-x / t) / z; end tmp_2 = tmp; end
code[x_, y_, z_, t_] := If[LessEqual[N[(z * t), $MachinePrecision], -5e+25], N[(N[((-x) / z), $MachinePrecision] / t), $MachinePrecision], If[LessEqual[N[(z * t), $MachinePrecision], 4e+15], N[(x / y), $MachinePrecision], N[(N[((-x) / t), $MachinePrecision] / z), $MachinePrecision]]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;z \cdot t \leq -5 \cdot 10^{+25}:\\
\;\;\;\;\frac{\frac{-x}{z}}{t}\\
\mathbf{elif}\;z \cdot t \leq 4 \cdot 10^{+15}:\\
\;\;\;\;\frac{x}{y}\\
\mathbf{else}:\\
\;\;\;\;\frac{\frac{-x}{t}}{z}\\
\end{array}
\end{array}
if (*.f64 z t) < -5.00000000000000024e25Initial program 90.9%
Taylor expanded in y around 0 76.6%
associate-*r/76.6%
neg-mul-176.6%
Simplified76.6%
neg-mul-176.6%
times-frac76.5%
Applied egg-rr76.5%
associate-*l/76.4%
mul-1-neg76.4%
Applied egg-rr76.4%
if -5.00000000000000024e25 < (*.f64 z t) < 4e15Initial program 99.9%
Taylor expanded in y around inf 82.2%
if 4e15 < (*.f64 z t) Initial program 94.4%
Taylor expanded in y around 0 82.8%
mul-1-neg82.8%
associate-/r*86.6%
distribute-neg-frac86.6%
Simplified86.6%
Final simplification81.8%
(FPCore (x y z t) :precision binary64 (if (or (<= (* z t) -2e+180) (not (<= (* z t) 2e+155))) (/ x (* z t)) (/ x y)))
double code(double x, double y, double z, double t) {
double tmp;
if (((z * t) <= -2e+180) || !((z * t) <= 2e+155)) {
tmp = x / (z * t);
} else {
tmp = x / y;
}
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 * t) <= (-2d+180)) .or. (.not. ((z * t) <= 2d+155))) then
tmp = x / (z * t)
else
tmp = x / y
end if
code = tmp
end function
public static double code(double x, double y, double z, double t) {
double tmp;
if (((z * t) <= -2e+180) || !((z * t) <= 2e+155)) {
tmp = x / (z * t);
} else {
tmp = x / y;
}
return tmp;
}
def code(x, y, z, t): tmp = 0 if ((z * t) <= -2e+180) or not ((z * t) <= 2e+155): tmp = x / (z * t) else: tmp = x / y return tmp
function code(x, y, z, t) tmp = 0.0 if ((Float64(z * t) <= -2e+180) || !(Float64(z * t) <= 2e+155)) tmp = Float64(x / Float64(z * t)); else tmp = Float64(x / y); end return tmp end
function tmp_2 = code(x, y, z, t) tmp = 0.0; if (((z * t) <= -2e+180) || ~(((z * t) <= 2e+155))) tmp = x / (z * t); else tmp = x / y; end tmp_2 = tmp; end
code[x_, y_, z_, t_] := If[Or[LessEqual[N[(z * t), $MachinePrecision], -2e+180], N[Not[LessEqual[N[(z * t), $MachinePrecision], 2e+155]], $MachinePrecision]], N[(x / N[(z * t), $MachinePrecision]), $MachinePrecision], N[(x / y), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;z \cdot t \leq -2 \cdot 10^{+180} \lor \neg \left(z \cdot t \leq 2 \cdot 10^{+155}\right):\\
\;\;\;\;\frac{x}{z \cdot t}\\
\mathbf{else}:\\
\;\;\;\;\frac{x}{y}\\
\end{array}
\end{array}
if (*.f64 z t) < -2e180 or 2.00000000000000001e155 < (*.f64 z t) Initial program 87.5%
Taylor expanded in y around 0 83.4%
associate-*r/83.4%
neg-mul-183.4%
Simplified83.4%
neg-mul-183.4%
times-frac95.7%
Applied egg-rr95.7%
frac-2neg95.7%
metadata-eval95.7%
frac-times83.4%
*-un-lft-identity83.4%
*-commutative83.4%
add-sqr-sqrt34.5%
sqrt-unprod57.9%
sqr-neg57.9%
sqrt-unprod30.3%
add-sqr-sqrt53.3%
Applied egg-rr53.3%
if -2e180 < (*.f64 z t) < 2.00000000000000001e155Initial program 99.8%
Taylor expanded in y around inf 67.3%
Final simplification63.4%
(FPCore (x y z t) :precision binary64 (if (<= (* z t) -1e+250) (/ -1.0 (* z (/ t x))) (/ x (- y (* z t)))))
double code(double x, double y, double z, double t) {
double tmp;
if ((z * t) <= -1e+250) {
tmp = -1.0 / (z * (t / x));
} else {
tmp = x / (y - (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 * t) <= (-1d+250)) then
tmp = (-1.0d0) / (z * (t / x))
else
tmp = x / (y - (z * t))
end if
code = tmp
end function
public static double code(double x, double y, double z, double t) {
double tmp;
if ((z * t) <= -1e+250) {
tmp = -1.0 / (z * (t / x));
} else {
tmp = x / (y - (z * t));
}
return tmp;
}
def code(x, y, z, t): tmp = 0 if (z * t) <= -1e+250: tmp = -1.0 / (z * (t / x)) else: tmp = x / (y - (z * t)) return tmp
function code(x, y, z, t) tmp = 0.0 if (Float64(z * t) <= -1e+250) tmp = Float64(-1.0 / Float64(z * Float64(t / x))); else tmp = Float64(x / Float64(y - Float64(z * t))); end return tmp end
function tmp_2 = code(x, y, z, t) tmp = 0.0; if ((z * t) <= -1e+250) tmp = -1.0 / (z * (t / x)); else tmp = x / (y - (z * t)); end tmp_2 = tmp; end
code[x_, y_, z_, t_] := If[LessEqual[N[(z * t), $MachinePrecision], -1e+250], N[(-1.0 / N[(z * N[(t / x), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], N[(x / N[(y - N[(z * t), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;z \cdot t \leq -1 \cdot 10^{+250}:\\
\;\;\;\;\frac{-1}{z \cdot \frac{t}{x}}\\
\mathbf{else}:\\
\;\;\;\;\frac{x}{y - z \cdot t}\\
\end{array}
\end{array}
if (*.f64 z t) < -9.9999999999999992e249Initial program 72.8%
Taylor expanded in y around 0 72.8%
associate-*r/72.8%
neg-mul-172.8%
Simplified72.8%
neg-mul-172.8%
times-frac99.6%
Applied egg-rr99.6%
*-commutative99.6%
frac-times72.8%
*-commutative72.8%
frac-times99.7%
clear-num99.6%
frac-times99.9%
metadata-eval99.9%
Applied egg-rr99.9%
if -9.9999999999999992e249 < (*.f64 z t) Initial program 98.5%
Final simplification98.6%
(FPCore (x y z t) :precision binary64 (/ x y))
double code(double x, double y, double z, double t) {
return x / y;
}
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
end function
public static double code(double x, double y, double z, double t) {
return x / y;
}
def code(x, y, z, t): return x / y
function code(x, y, z, t) return Float64(x / y) end
function tmp = code(x, y, z, t) tmp = x / y; end
code[x_, y_, z_, t_] := N[(x / y), $MachinePrecision]
\begin{array}{l}
\\
\frac{x}{y}
\end{array}
Initial program 96.4%
Taylor expanded in y around inf 52.0%
Final simplification52.0%
(FPCore (x y z t)
:precision binary64
(let* ((t_1 (/ 1.0 (- (/ y x) (* (/ z x) t)))))
(if (< x -1.618195973607049e+50)
t_1
(if (< x 2.1378306434876444e+131) (/ x (- y (* z t))) t_1))))
double code(double x, double y, double z, double t) {
double t_1 = 1.0 / ((y / x) - ((z / x) * t));
double tmp;
if (x < -1.618195973607049e+50) {
tmp = t_1;
} else if (x < 2.1378306434876444e+131) {
tmp = x / (y - (z * t));
} else {
tmp = t_1;
}
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) :: t_1
real(8) :: tmp
t_1 = 1.0d0 / ((y / x) - ((z / x) * t))
if (x < (-1.618195973607049d+50)) then
tmp = t_1
else if (x < 2.1378306434876444d+131) then
tmp = x / (y - (z * t))
else
tmp = t_1
end if
code = tmp
end function
public static double code(double x, double y, double z, double t) {
double t_1 = 1.0 / ((y / x) - ((z / x) * t));
double tmp;
if (x < -1.618195973607049e+50) {
tmp = t_1;
} else if (x < 2.1378306434876444e+131) {
tmp = x / (y - (z * t));
} else {
tmp = t_1;
}
return tmp;
}
def code(x, y, z, t): t_1 = 1.0 / ((y / x) - ((z / x) * t)) tmp = 0 if x < -1.618195973607049e+50: tmp = t_1 elif x < 2.1378306434876444e+131: tmp = x / (y - (z * t)) else: tmp = t_1 return tmp
function code(x, y, z, t) t_1 = Float64(1.0 / Float64(Float64(y / x) - Float64(Float64(z / x) * t))) tmp = 0.0 if (x < -1.618195973607049e+50) tmp = t_1; elseif (x < 2.1378306434876444e+131) tmp = Float64(x / Float64(y - Float64(z * t))); else tmp = t_1; end return tmp end
function tmp_2 = code(x, y, z, t) t_1 = 1.0 / ((y / x) - ((z / x) * t)); tmp = 0.0; if (x < -1.618195973607049e+50) tmp = t_1; elseif (x < 2.1378306434876444e+131) tmp = x / (y - (z * t)); else tmp = t_1; end tmp_2 = tmp; end
code[x_, y_, z_, t_] := Block[{t$95$1 = N[(1.0 / N[(N[(y / x), $MachinePrecision] - N[(N[(z / x), $MachinePrecision] * t), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]}, If[Less[x, -1.618195973607049e+50], t$95$1, If[Less[x, 2.1378306434876444e+131], N[(x / N[(y - N[(z * t), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], t$95$1]]]
\begin{array}{l}
\\
\begin{array}{l}
t_1 := \frac{1}{\frac{y}{x} - \frac{z}{x} \cdot t}\\
\mathbf{if}\;x < -1.618195973607049 \cdot 10^{+50}:\\
\;\;\;\;t_1\\
\mathbf{elif}\;x < 2.1378306434876444 \cdot 10^{+131}:\\
\;\;\;\;\frac{x}{y - z \cdot t}\\
\mathbf{else}:\\
\;\;\;\;t_1\\
\end{array}
\end{array}
herbie shell --seed 2023314
(FPCore (x y z t)
:name "Diagrams.Solve.Tridiagonal:solveTriDiagonal from diagrams-solve-0.1, B"
:precision binary64
:herbie-target
(if (< x -1.618195973607049e+50) (/ 1.0 (- (/ y x) (* (/ z x) t))) (if (< x 2.1378306434876444e+131) (/ x (- y (* z t))) (/ 1.0 (- (/ y x) (* (/ z x) t)))))
(/ x (- y (* z t))))