
(FPCore (x y z t a) :precision binary64 (+ x (/ (* y (- z t)) a)))
double code(double x, double y, double z, double t, double a) {
return x + ((y * (z - t)) / a);
}
real(8) function code(x, y, z, t, a)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
real(8), intent (in) :: a
code = x + ((y * (z - t)) / a)
end function
public static double code(double x, double y, double z, double t, double a) {
return x + ((y * (z - t)) / a);
}
def code(x, y, z, t, a): return x + ((y * (z - t)) / a)
function code(x, y, z, t, a) return Float64(x + Float64(Float64(y * Float64(z - t)) / a)) end
function tmp = code(x, y, z, t, a) tmp = x + ((y * (z - t)) / a); end
code[x_, y_, z_, t_, a_] := N[(x + N[(N[(y * N[(z - t), $MachinePrecision]), $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
x + \frac{y \cdot \left(z - t\right)}{a}
\end{array}
Sampling outcomes in binary64 precision:
Herbie found 9 alternatives:
| Alternative | Accuracy | Speedup |
|---|
(FPCore (x y z t a) :precision binary64 (+ x (/ (* y (- z t)) a)))
double code(double x, double y, double z, double t, double a) {
return x + ((y * (z - t)) / a);
}
real(8) function code(x, y, z, t, a)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
real(8), intent (in) :: a
code = x + ((y * (z - t)) / a)
end function
public static double code(double x, double y, double z, double t, double a) {
return x + ((y * (z - t)) / a);
}
def code(x, y, z, t, a): return x + ((y * (z - t)) / a)
function code(x, y, z, t, a) return Float64(x + Float64(Float64(y * Float64(z - t)) / a)) end
function tmp = code(x, y, z, t, a) tmp = x + ((y * (z - t)) / a); end
code[x_, y_, z_, t_, a_] := N[(x + N[(N[(y * N[(z - t), $MachinePrecision]), $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
x + \frac{y \cdot \left(z - t\right)}{a}
\end{array}
(FPCore (x y z t a)
:precision binary64
(let* ((t_1 (* y (- z t))))
(if (<= t_1 (- INFINITY))
(+ x (/ y (/ a (- z t))))
(if (<= t_1 1e+109) (+ x (/ t_1 a)) (fma (/ (- z t) a) y x)))))
double code(double x, double y, double z, double t, double a) {
double t_1 = y * (z - t);
double tmp;
if (t_1 <= -((double) INFINITY)) {
tmp = x + (y / (a / (z - t)));
} else if (t_1 <= 1e+109) {
tmp = x + (t_1 / a);
} else {
tmp = fma(((z - t) / a), y, x);
}
return tmp;
}
function code(x, y, z, t, a) t_1 = Float64(y * Float64(z - t)) tmp = 0.0 if (t_1 <= Float64(-Inf)) tmp = Float64(x + Float64(y / Float64(a / Float64(z - t)))); elseif (t_1 <= 1e+109) tmp = Float64(x + Float64(t_1 / a)); else tmp = fma(Float64(Float64(z - t) / a), y, x); end return tmp end
code[x_, y_, z_, t_, a_] := Block[{t$95$1 = N[(y * N[(z - t), $MachinePrecision]), $MachinePrecision]}, If[LessEqual[t$95$1, (-Infinity)], N[(x + N[(y / N[(a / N[(z - t), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], If[LessEqual[t$95$1, 1e+109], N[(x + N[(t$95$1 / a), $MachinePrecision]), $MachinePrecision], N[(N[(N[(z - t), $MachinePrecision] / a), $MachinePrecision] * y + x), $MachinePrecision]]]]
\begin{array}{l}
\\
\begin{array}{l}
t_1 := y \cdot \left(z - t\right)\\
\mathbf{if}\;t\_1 \leq -\infty:\\
\;\;\;\;x + \frac{y}{\frac{a}{z - t}}\\
\mathbf{elif}\;t\_1 \leq 10^{+109}:\\
\;\;\;\;x + \frac{t\_1}{a}\\
\mathbf{else}:\\
\;\;\;\;\mathsf{fma}\left(\frac{z - t}{a}, y, x\right)\\
\end{array}
\end{array}
if (*.f64 y (-.f64 z t)) < -inf.0Initial program 54.6%
lift-/.f64N/A
lift-*.f64N/A
associate-/l*N/A
clear-numN/A
un-div-invN/A
lower-/.f64N/A
lower-/.f6499.9
Applied rewrites99.9%
if -inf.0 < (*.f64 y (-.f64 z t)) < 9.99999999999999982e108Initial program 99.8%
if 9.99999999999999982e108 < (*.f64 y (-.f64 z t)) Initial program 90.4%
lift-+.f64N/A
+-commutativeN/A
lift-/.f64N/A
lift-*.f64N/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f64N/A
lower-/.f64100.0
Applied rewrites100.0%
(FPCore (x y z t a) :precision binary64 (let* ((t_1 (* y (- z t))) (t_2 (fma (/ (- z t) a) y x))) (if (<= t_1 (- INFINITY)) t_2 (if (<= t_1 1e+109) (+ x (/ t_1 a)) t_2))))
double code(double x, double y, double z, double t, double a) {
double t_1 = y * (z - t);
double t_2 = fma(((z - t) / a), y, x);
double tmp;
if (t_1 <= -((double) INFINITY)) {
tmp = t_2;
} else if (t_1 <= 1e+109) {
tmp = x + (t_1 / a);
} else {
tmp = t_2;
}
return tmp;
}
function code(x, y, z, t, a) t_1 = Float64(y * Float64(z - t)) t_2 = fma(Float64(Float64(z - t) / a), y, x) tmp = 0.0 if (t_1 <= Float64(-Inf)) tmp = t_2; elseif (t_1 <= 1e+109) tmp = Float64(x + Float64(t_1 / a)); else tmp = t_2; end return tmp end
code[x_, y_, z_, t_, a_] := Block[{t$95$1 = N[(y * N[(z - t), $MachinePrecision]), $MachinePrecision]}, Block[{t$95$2 = N[(N[(N[(z - t), $MachinePrecision] / a), $MachinePrecision] * y + x), $MachinePrecision]}, If[LessEqual[t$95$1, (-Infinity)], t$95$2, If[LessEqual[t$95$1, 1e+109], N[(x + N[(t$95$1 / a), $MachinePrecision]), $MachinePrecision], t$95$2]]]]
\begin{array}{l}
\\
\begin{array}{l}
t_1 := y \cdot \left(z - t\right)\\
t_2 := \mathsf{fma}\left(\frac{z - t}{a}, y, x\right)\\
\mathbf{if}\;t\_1 \leq -\infty:\\
\;\;\;\;t\_2\\
\mathbf{elif}\;t\_1 \leq 10^{+109}:\\
\;\;\;\;x + \frac{t\_1}{a}\\
\mathbf{else}:\\
\;\;\;\;t\_2\\
\end{array}
\end{array}
if (*.f64 y (-.f64 z t)) < -inf.0 or 9.99999999999999982e108 < (*.f64 y (-.f64 z t)) Initial program 79.1%
lift-+.f64N/A
+-commutativeN/A
lift-/.f64N/A
lift-*.f64N/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f64N/A
lower-/.f6499.9
Applied rewrites99.9%
if -inf.0 < (*.f64 y (-.f64 z t)) < 9.99999999999999982e108Initial program 99.8%
(FPCore (x y z t a) :precision binary64 (if (<= (/ (* y (- z t)) a) 5e+129) (fma y (/ z a) x) (* z (/ y a))))
double code(double x, double y, double z, double t, double a) {
double tmp;
if (((y * (z - t)) / a) <= 5e+129) {
tmp = fma(y, (z / a), x);
} else {
tmp = z * (y / a);
}
return tmp;
}
function code(x, y, z, t, a) tmp = 0.0 if (Float64(Float64(y * Float64(z - t)) / a) <= 5e+129) tmp = fma(y, Float64(z / a), x); else tmp = Float64(z * Float64(y / a)); end return tmp end
code[x_, y_, z_, t_, a_] := If[LessEqual[N[(N[(y * N[(z - t), $MachinePrecision]), $MachinePrecision] / a), $MachinePrecision], 5e+129], N[(y * N[(z / a), $MachinePrecision] + x), $MachinePrecision], N[(z * N[(y / a), $MachinePrecision]), $MachinePrecision]]
\begin{array}{l}
\\
\begin{array}{l}
\mathbf{if}\;\frac{y \cdot \left(z - t\right)}{a} \leq 5 \cdot 10^{+129}:\\
\;\;\;\;\mathsf{fma}\left(y, \frac{z}{a}, x\right)\\
\mathbf{else}:\\
\;\;\;\;z \cdot \frac{y}{a}\\
\end{array}
\end{array}
if (/.f64 (*.f64 y (-.f64 z t)) a) < 5.0000000000000003e129Initial program 95.4%
Taylor expanded in t around 0
+-commutativeN/A
associate-/l*N/A
lower-fma.f64N/A
lower-/.f6473.7
Applied rewrites73.7%
if 5.0000000000000003e129 < (/.f64 (*.f64 y (-.f64 z t)) a) Initial program 89.5%
Taylor expanded in z around inf
lower-/.f64N/A
lower-*.f6443.9
Applied rewrites43.9%
Applied rewrites54.1%
Final simplification68.8%
(FPCore (x y z t a) :precision binary64 (let* ((t_1 (fma (/ y a) (- t) x))) (if (<= t -0.0072) t_1 (if (<= t 2.5e+42) (fma (/ y a) z x) t_1))))
double code(double x, double y, double z, double t, double a) {
double t_1 = fma((y / a), -t, x);
double tmp;
if (t <= -0.0072) {
tmp = t_1;
} else if (t <= 2.5e+42) {
tmp = fma((y / a), z, x);
} else {
tmp = t_1;
}
return tmp;
}
function code(x, y, z, t, a) t_1 = fma(Float64(y / a), Float64(-t), x) tmp = 0.0 if (t <= -0.0072) tmp = t_1; elseif (t <= 2.5e+42) tmp = fma(Float64(y / a), z, x); else tmp = t_1; end return tmp end
code[x_, y_, z_, t_, a_] := Block[{t$95$1 = N[(N[(y / a), $MachinePrecision] * (-t) + x), $MachinePrecision]}, If[LessEqual[t, -0.0072], t$95$1, If[LessEqual[t, 2.5e+42], N[(N[(y / a), $MachinePrecision] * z + x), $MachinePrecision], t$95$1]]]
\begin{array}{l}
\\
\begin{array}{l}
t_1 := \mathsf{fma}\left(\frac{y}{a}, -t, x\right)\\
\mathbf{if}\;t \leq -0.0072:\\
\;\;\;\;t\_1\\
\mathbf{elif}\;t \leq 2.5 \cdot 10^{+42}:\\
\;\;\;\;\mathsf{fma}\left(\frac{y}{a}, z, x\right)\\
\mathbf{else}:\\
\;\;\;\;t\_1\\
\end{array}
\end{array}
if t < -0.0071999999999999998 or 2.50000000000000003e42 < t Initial program 94.1%
lift-+.f64N/A
+-commutativeN/A
lift-/.f64N/A
lift-*.f64N/A
*-commutativeN/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f64N/A
lower-/.f6496.8
Applied rewrites96.8%
Taylor expanded in z around 0
mul-1-negN/A
lower-neg.f6489.3
Applied rewrites89.3%
if -0.0071999999999999998 < t < 2.50000000000000003e42Initial program 93.8%
lift-+.f64N/A
+-commutativeN/A
lift-/.f64N/A
lift-*.f64N/A
*-commutativeN/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f64N/A
lower-/.f6495.7
Applied rewrites95.7%
Taylor expanded in t around 0
+-commutativeN/A
associate-/l*N/A
lower-fma.f64N/A
lower-/.f6486.5
Applied rewrites86.5%
Applied rewrites90.1%
(FPCore (x y z t a) :precision binary64 (let* ((t_1 (- x (/ (* y t) a)))) (if (<= t -1.18e-40) t_1 (if (<= t 2.5e+42) (fma (/ y a) z x) t_1))))
double code(double x, double y, double z, double t, double a) {
double t_1 = x - ((y * t) / a);
double tmp;
if (t <= -1.18e-40) {
tmp = t_1;
} else if (t <= 2.5e+42) {
tmp = fma((y / a), z, x);
} else {
tmp = t_1;
}
return tmp;
}
function code(x, y, z, t, a) t_1 = Float64(x - Float64(Float64(y * t) / a)) tmp = 0.0 if (t <= -1.18e-40) tmp = t_1; elseif (t <= 2.5e+42) tmp = fma(Float64(y / a), z, x); else tmp = t_1; end return tmp end
code[x_, y_, z_, t_, a_] := Block[{t$95$1 = N[(x - N[(N[(y * t), $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision]}, If[LessEqual[t, -1.18e-40], t$95$1, If[LessEqual[t, 2.5e+42], N[(N[(y / a), $MachinePrecision] * z + x), $MachinePrecision], t$95$1]]]
\begin{array}{l}
\\
\begin{array}{l}
t_1 := x - \frac{y \cdot t}{a}\\
\mathbf{if}\;t \leq -1.18 \cdot 10^{-40}:\\
\;\;\;\;t\_1\\
\mathbf{elif}\;t \leq 2.5 \cdot 10^{+42}:\\
\;\;\;\;\mathsf{fma}\left(\frac{y}{a}, z, x\right)\\
\mathbf{else}:\\
\;\;\;\;t\_1\\
\end{array}
\end{array}
if t < -1.1799999999999999e-40 or 2.50000000000000003e42 < t Initial program 94.5%
Taylor expanded in z around 0
mul-1-negN/A
unsub-negN/A
lower--.f64N/A
lower-/.f64N/A
*-commutativeN/A
lower-*.f6485.7
Applied rewrites85.7%
if -1.1799999999999999e-40 < t < 2.50000000000000003e42Initial program 93.3%
lift-+.f64N/A
+-commutativeN/A
lift-/.f64N/A
lift-*.f64N/A
*-commutativeN/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f64N/A
lower-/.f6496.9
Applied rewrites96.9%
Taylor expanded in t around 0
+-commutativeN/A
associate-/l*N/A
lower-fma.f64N/A
lower-/.f6487.5
Applied rewrites87.5%
Applied rewrites91.6%
(FPCore (x y z t a) :precision binary64 (let* ((t_1 (* t (/ (- y) a)))) (if (<= t -3.2e+143) t_1 (if (<= t 4.3e+107) (fma (/ y a) z x) t_1))))
double code(double x, double y, double z, double t, double a) {
double t_1 = t * (-y / a);
double tmp;
if (t <= -3.2e+143) {
tmp = t_1;
} else if (t <= 4.3e+107) {
tmp = fma((y / a), z, x);
} else {
tmp = t_1;
}
return tmp;
}
function code(x, y, z, t, a) t_1 = Float64(t * Float64(Float64(-y) / a)) tmp = 0.0 if (t <= -3.2e+143) tmp = t_1; elseif (t <= 4.3e+107) tmp = fma(Float64(y / a), z, x); else tmp = t_1; end return tmp end
code[x_, y_, z_, t_, a_] := Block[{t$95$1 = N[(t * N[((-y) / a), $MachinePrecision]), $MachinePrecision]}, If[LessEqual[t, -3.2e+143], t$95$1, If[LessEqual[t, 4.3e+107], N[(N[(y / a), $MachinePrecision] * z + x), $MachinePrecision], t$95$1]]]
\begin{array}{l}
\\
\begin{array}{l}
t_1 := t \cdot \frac{-y}{a}\\
\mathbf{if}\;t \leq -3.2 \cdot 10^{+143}:\\
\;\;\;\;t\_1\\
\mathbf{elif}\;t \leq 4.3 \cdot 10^{+107}:\\
\;\;\;\;\mathsf{fma}\left(\frac{y}{a}, z, x\right)\\
\mathbf{else}:\\
\;\;\;\;t\_1\\
\end{array}
\end{array}
if t < -3.20000000000000016e143 or 4.3e107 < t Initial program 93.2%
Taylor expanded in t around inf
mul-1-negN/A
associate-/l*N/A
distribute-rgt-neg-inN/A
mul-1-negN/A
lower-*.f64N/A
associate-*r/N/A
lower-/.f64N/A
mul-1-negN/A
lower-neg.f6472.5
Applied rewrites72.5%
if -3.20000000000000016e143 < t < 4.3e107Initial program 94.2%
lift-+.f64N/A
+-commutativeN/A
lift-/.f64N/A
lift-*.f64N/A
*-commutativeN/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f64N/A
lower-/.f6496.7
Applied rewrites96.7%
Taylor expanded in t around 0
+-commutativeN/A
associate-/l*N/A
lower-fma.f64N/A
lower-/.f6481.2
Applied rewrites81.2%
Applied rewrites84.9%
(FPCore (x y z t a) :precision binary64 (fma (/ y a) (- z t) x))
double code(double x, double y, double z, double t, double a) {
return fma((y / a), (z - t), x);
}
function code(x, y, z, t, a) return fma(Float64(y / a), Float64(z - t), x) end
code[x_, y_, z_, t_, a_] := N[(N[(y / a), $MachinePrecision] * N[(z - t), $MachinePrecision] + x), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(\frac{y}{a}, z - t, x\right)
\end{array}
Initial program 93.9%
lift-+.f64N/A
+-commutativeN/A
lift-/.f64N/A
lift-*.f64N/A
*-commutativeN/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f64N/A
lower-/.f6496.2
Applied rewrites96.2%
(FPCore (x y z t a) :precision binary64 (fma (/ y a) z x))
double code(double x, double y, double z, double t, double a) {
return fma((y / a), z, x);
}
function code(x, y, z, t, a) return fma(Float64(y / a), z, x) end
code[x_, y_, z_, t_, a_] := N[(N[(y / a), $MachinePrecision] * z + x), $MachinePrecision]
\begin{array}{l}
\\
\mathsf{fma}\left(\frac{y}{a}, z, x\right)
\end{array}
Initial program 93.9%
lift-+.f64N/A
+-commutativeN/A
lift-/.f64N/A
lift-*.f64N/A
*-commutativeN/A
associate-/l*N/A
*-commutativeN/A
lower-fma.f64N/A
lower-/.f6496.2
Applied rewrites96.2%
Taylor expanded in t around 0
+-commutativeN/A
associate-/l*N/A
lower-fma.f64N/A
lower-/.f6467.2
Applied rewrites67.2%
Applied rewrites71.4%
(FPCore (x y z t a) :precision binary64 (* z (/ y a)))
double code(double x, double y, double z, double t, double a) {
return z * (y / a);
}
real(8) function code(x, y, z, t, a)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
real(8), intent (in) :: a
code = z * (y / a)
end function
public static double code(double x, double y, double z, double t, double a) {
return z * (y / a);
}
def code(x, y, z, t, a): return z * (y / a)
function code(x, y, z, t, a) return Float64(z * Float64(y / a)) end
function tmp = code(x, y, z, t, a) tmp = z * (y / a); end
code[x_, y_, z_, t_, a_] := N[(z * N[(y / a), $MachinePrecision]), $MachinePrecision]
\begin{array}{l}
\\
z \cdot \frac{y}{a}
\end{array}
Initial program 93.9%
Taylor expanded in z around inf
lower-/.f64N/A
lower-*.f6428.4
Applied rewrites28.4%
Applied rewrites31.0%
Final simplification31.0%
(FPCore (x y z t a)
:precision binary64
(let* ((t_1 (/ a (- z t))))
(if (< y -1.0761266216389975e-10)
(+ x (/ 1.0 (/ t_1 y)))
(if (< y 2.894426862792089e-49)
(+ x (/ (* y (- z t)) a))
(+ x (/ y t_1))))))
double code(double x, double y, double z, double t, double a) {
double t_1 = a / (z - t);
double tmp;
if (y < -1.0761266216389975e-10) {
tmp = x + (1.0 / (t_1 / y));
} else if (y < 2.894426862792089e-49) {
tmp = x + ((y * (z - t)) / a);
} else {
tmp = x + (y / t_1);
}
return tmp;
}
real(8) function code(x, y, z, t, a)
real(8), intent (in) :: x
real(8), intent (in) :: y
real(8), intent (in) :: z
real(8), intent (in) :: t
real(8), intent (in) :: a
real(8) :: t_1
real(8) :: tmp
t_1 = a / (z - t)
if (y < (-1.0761266216389975d-10)) then
tmp = x + (1.0d0 / (t_1 / y))
else if (y < 2.894426862792089d-49) then
tmp = x + ((y * (z - t)) / a)
else
tmp = x + (y / t_1)
end if
code = tmp
end function
public static double code(double x, double y, double z, double t, double a) {
double t_1 = a / (z - t);
double tmp;
if (y < -1.0761266216389975e-10) {
tmp = x + (1.0 / (t_1 / y));
} else if (y < 2.894426862792089e-49) {
tmp = x + ((y * (z - t)) / a);
} else {
tmp = x + (y / t_1);
}
return tmp;
}
def code(x, y, z, t, a): t_1 = a / (z - t) tmp = 0 if y < -1.0761266216389975e-10: tmp = x + (1.0 / (t_1 / y)) elif y < 2.894426862792089e-49: tmp = x + ((y * (z - t)) / a) else: tmp = x + (y / t_1) return tmp
function code(x, y, z, t, a) t_1 = Float64(a / Float64(z - t)) tmp = 0.0 if (y < -1.0761266216389975e-10) tmp = Float64(x + Float64(1.0 / Float64(t_1 / y))); elseif (y < 2.894426862792089e-49) tmp = Float64(x + Float64(Float64(y * Float64(z - t)) / a)); else tmp = Float64(x + Float64(y / t_1)); end return tmp end
function tmp_2 = code(x, y, z, t, a) t_1 = a / (z - t); tmp = 0.0; if (y < -1.0761266216389975e-10) tmp = x + (1.0 / (t_1 / y)); elseif (y < 2.894426862792089e-49) tmp = x + ((y * (z - t)) / a); else tmp = x + (y / t_1); end tmp_2 = tmp; end
code[x_, y_, z_, t_, a_] := Block[{t$95$1 = N[(a / N[(z - t), $MachinePrecision]), $MachinePrecision]}, If[Less[y, -1.0761266216389975e-10], N[(x + N[(1.0 / N[(t$95$1 / y), $MachinePrecision]), $MachinePrecision]), $MachinePrecision], If[Less[y, 2.894426862792089e-49], N[(x + N[(N[(y * N[(z - t), $MachinePrecision]), $MachinePrecision] / a), $MachinePrecision]), $MachinePrecision], N[(x + N[(y / t$95$1), $MachinePrecision]), $MachinePrecision]]]]
\begin{array}{l}
\\
\begin{array}{l}
t_1 := \frac{a}{z - t}\\
\mathbf{if}\;y < -1.0761266216389975 \cdot 10^{-10}:\\
\;\;\;\;x + \frac{1}{\frac{t\_1}{y}}\\
\mathbf{elif}\;y < 2.894426862792089 \cdot 10^{-49}:\\
\;\;\;\;x + \frac{y \cdot \left(z - t\right)}{a}\\
\mathbf{else}:\\
\;\;\;\;x + \frac{y}{t\_1}\\
\end{array}
\end{array}
herbie shell --seed 2024233
(FPCore (x y z t a)
:name "Optimisation.CirclePacking:place from circle-packing-0.1.0.4, E"
:precision binary64
:alt
(! :herbie-platform default (if (< y -430450648655599/4000000000000000000000000) (+ x (/ 1 (/ (/ a (- z t)) y))) (if (< y 2894426862792089/10000000000000000000000000000000000000000000000000000000000000000) (+ x (/ (* y (- z t)) a)) (+ x (/ y (/ a (- z t)))))))
(+ x (/ (* y (- z t)) a)))