?

Average Error: 2.1 → 1.2
Time: 50.9s
Precision: binary64
Cost: 20552

?

\[\frac{x \cdot e^{\left(y \cdot \log z + \left(t - 1\right) \cdot \log a\right) - b}}{y} \]
\[\begin{array}{l} t_1 := y \cdot \log z\\ t_2 := \frac{\frac{e^{t_1 + \left(\left(t + -1\right) \cdot \log a - b\right)}}{y}}{\frac{1}{x}}\\ \mathbf{if}\;x \leq -5 \cdot 10^{-33}:\\ \;\;\;\;t_2\\ \mathbf{elif}\;x \leq 2.9 \cdot 10^{+75}:\\ \;\;\;\;e^{\left(t_1 + \left(t - 1\right) \cdot \log a\right) - b} \cdot \frac{x}{y}\\ \mathbf{else}:\\ \;\;\;\;t_2\\ \end{array} \]
(FPCore (x y z t a b)
 :precision binary64
 (/ (* x (exp (- (+ (* y (log z)) (* (- t 1.0) (log a))) b))) y))
(FPCore (x y z t a b)
 :precision binary64
 (let* ((t_1 (* y (log z)))
        (t_2 (/ (/ (exp (+ t_1 (- (* (+ t -1.0) (log a)) b))) y) (/ 1.0 x))))
   (if (<= x -5e-33)
     t_2
     (if (<= x 2.9e+75)
       (* (exp (- (+ t_1 (* (- t 1.0) (log a))) b)) (/ x y))
       t_2))))
double code(double x, double y, double z, double t, double a, double b) {
	return (x * exp((((y * log(z)) + ((t - 1.0) * log(a))) - b))) / y;
}
double code(double x, double y, double z, double t, double a, double b) {
	double t_1 = y * log(z);
	double t_2 = (exp((t_1 + (((t + -1.0) * log(a)) - b))) / y) / (1.0 / x);
	double tmp;
	if (x <= -5e-33) {
		tmp = t_2;
	} else if (x <= 2.9e+75) {
		tmp = exp(((t_1 + ((t - 1.0) * log(a))) - b)) * (x / y);
	} else {
		tmp = t_2;
	}
	return tmp;
}
real(8) function code(x, y, z, t, a, b)
    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), intent (in) :: b
    code = (x * exp((((y * log(z)) + ((t - 1.0d0) * log(a))) - b))) / y
end function
real(8) function code(x, y, z, t, a, b)
    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), intent (in) :: b
    real(8) :: t_1
    real(8) :: t_2
    real(8) :: tmp
    t_1 = y * log(z)
    t_2 = (exp((t_1 + (((t + (-1.0d0)) * log(a)) - b))) / y) / (1.0d0 / x)
    if (x <= (-5d-33)) then
        tmp = t_2
    else if (x <= 2.9d+75) then
        tmp = exp(((t_1 + ((t - 1.0d0) * log(a))) - b)) * (x / y)
    else
        tmp = t_2
    end if
    code = tmp
end function
public static double code(double x, double y, double z, double t, double a, double b) {
	return (x * Math.exp((((y * Math.log(z)) + ((t - 1.0) * Math.log(a))) - b))) / y;
}
public static double code(double x, double y, double z, double t, double a, double b) {
	double t_1 = y * Math.log(z);
	double t_2 = (Math.exp((t_1 + (((t + -1.0) * Math.log(a)) - b))) / y) / (1.0 / x);
	double tmp;
	if (x <= -5e-33) {
		tmp = t_2;
	} else if (x <= 2.9e+75) {
		tmp = Math.exp(((t_1 + ((t - 1.0) * Math.log(a))) - b)) * (x / y);
	} else {
		tmp = t_2;
	}
	return tmp;
}
def code(x, y, z, t, a, b):
	return (x * math.exp((((y * math.log(z)) + ((t - 1.0) * math.log(a))) - b))) / y
def code(x, y, z, t, a, b):
	t_1 = y * math.log(z)
	t_2 = (math.exp((t_1 + (((t + -1.0) * math.log(a)) - b))) / y) / (1.0 / x)
	tmp = 0
	if x <= -5e-33:
		tmp = t_2
	elif x <= 2.9e+75:
		tmp = math.exp(((t_1 + ((t - 1.0) * math.log(a))) - b)) * (x / y)
	else:
		tmp = t_2
	return tmp
function code(x, y, z, t, a, b)
	return Float64(Float64(x * exp(Float64(Float64(Float64(y * log(z)) + Float64(Float64(t - 1.0) * log(a))) - b))) / y)
end
function code(x, y, z, t, a, b)
	t_1 = Float64(y * log(z))
	t_2 = Float64(Float64(exp(Float64(t_1 + Float64(Float64(Float64(t + -1.0) * log(a)) - b))) / y) / Float64(1.0 / x))
	tmp = 0.0
	if (x <= -5e-33)
		tmp = t_2;
	elseif (x <= 2.9e+75)
		tmp = Float64(exp(Float64(Float64(t_1 + Float64(Float64(t - 1.0) * log(a))) - b)) * Float64(x / y));
	else
		tmp = t_2;
	end
	return tmp
end
function tmp = code(x, y, z, t, a, b)
	tmp = (x * exp((((y * log(z)) + ((t - 1.0) * log(a))) - b))) / y;
end
function tmp_2 = code(x, y, z, t, a, b)
	t_1 = y * log(z);
	t_2 = (exp((t_1 + (((t + -1.0) * log(a)) - b))) / y) / (1.0 / x);
	tmp = 0.0;
	if (x <= -5e-33)
		tmp = t_2;
	elseif (x <= 2.9e+75)
		tmp = exp(((t_1 + ((t - 1.0) * log(a))) - b)) * (x / y);
	else
		tmp = t_2;
	end
	tmp_2 = tmp;
end
code[x_, y_, z_, t_, a_, b_] := N[(N[(x * N[Exp[N[(N[(N[(y * N[Log[z], $MachinePrecision]), $MachinePrecision] + N[(N[(t - 1.0), $MachinePrecision] * N[Log[a], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] - b), $MachinePrecision]], $MachinePrecision]), $MachinePrecision] / y), $MachinePrecision]
code[x_, y_, z_, t_, a_, b_] := Block[{t$95$1 = N[(y * N[Log[z], $MachinePrecision]), $MachinePrecision]}, Block[{t$95$2 = N[(N[(N[Exp[N[(t$95$1 + N[(N[(N[(t + -1.0), $MachinePrecision] * N[Log[a], $MachinePrecision]), $MachinePrecision] - b), $MachinePrecision]), $MachinePrecision]], $MachinePrecision] / y), $MachinePrecision] / N[(1.0 / x), $MachinePrecision]), $MachinePrecision]}, If[LessEqual[x, -5e-33], t$95$2, If[LessEqual[x, 2.9e+75], N[(N[Exp[N[(N[(t$95$1 + N[(N[(t - 1.0), $MachinePrecision] * N[Log[a], $MachinePrecision]), $MachinePrecision]), $MachinePrecision] - b), $MachinePrecision]], $MachinePrecision] * N[(x / y), $MachinePrecision]), $MachinePrecision], t$95$2]]]]
\frac{x \cdot e^{\left(y \cdot \log z + \left(t - 1\right) \cdot \log a\right) - b}}{y}
\begin{array}{l}
t_1 := y \cdot \log z\\
t_2 := \frac{\frac{e^{t_1 + \left(\left(t + -1\right) \cdot \log a - b\right)}}{y}}{\frac{1}{x}}\\
\mathbf{if}\;x \leq -5 \cdot 10^{-33}:\\
\;\;\;\;t_2\\

\mathbf{elif}\;x \leq 2.9 \cdot 10^{+75}:\\
\;\;\;\;e^{\left(t_1 + \left(t - 1\right) \cdot \log a\right) - b} \cdot \frac{x}{y}\\

\mathbf{else}:\\
\;\;\;\;t_2\\


\end{array}

Error?

Try it out?

Your Program's Arguments

Results

Enter valid numbers for all inputs

Target

Original2.1
Target10.9
Herbie1.2
\[\begin{array}{l} \mathbf{if}\;t < -0.8845848504127471:\\ \;\;\;\;\frac{x \cdot \frac{{a}^{\left(t - 1\right)}}{y}}{\left(b + 1\right) - y \cdot \log z}\\ \mathbf{elif}\;t < 852031.2288374073:\\ \;\;\;\;\frac{\frac{x}{y} \cdot {a}^{\left(t - 1\right)}}{e^{b - \log z \cdot y}}\\ \mathbf{else}:\\ \;\;\;\;\frac{x \cdot \frac{{a}^{\left(t - 1\right)}}{y}}{\left(b + 1\right) - y \cdot \log z}\\ \end{array} \]

Derivation?

  1. Split input into 2 regimes
  2. if x < -5.00000000000000028e-33 or 2.8999999999999998e75 < x

    1. Initial program 0.8

      \[\frac{x \cdot e^{\left(y \cdot \log z + \left(t - 1\right) \cdot \log a\right) - b}}{y} \]
    2. Simplified0.9

      \[\leadsto \color{blue}{x \cdot \frac{e^{y \cdot \log z + \left(\left(t - 1\right) \cdot \log a - b\right)}}{y}} \]
      Proof

      [Start]0.8

      \[ \frac{x \cdot e^{\left(y \cdot \log z + \left(t - 1\right) \cdot \log a\right) - b}}{y} \]

      rational.json-simplify-2 [=>]0.8

      \[ \frac{\color{blue}{e^{\left(y \cdot \log z + \left(t - 1\right) \cdot \log a\right) - b} \cdot x}}{y} \]

      rational.json-simplify-49 [=>]0.9

      \[ \color{blue}{x \cdot \frac{e^{\left(y \cdot \log z + \left(t - 1\right) \cdot \log a\right) - b}}{y}} \]

      rational.json-simplify-1 [=>]0.9

      \[ x \cdot \frac{e^{\color{blue}{\left(\left(t - 1\right) \cdot \log a + y \cdot \log z\right)} - b}}{y} \]

      rational.json-simplify-48 [=>]0.9

      \[ x \cdot \frac{e^{\color{blue}{y \cdot \log z + \left(\left(t - 1\right) \cdot \log a - b\right)}}}{y} \]
    3. Applied egg-rr0.9

      \[\leadsto \color{blue}{\frac{\frac{e^{y \cdot \log z + \left(\left(t + -1\right) \cdot \log a - b\right)}}{y}}{\frac{1}{x}}} \]

    if -5.00000000000000028e-33 < x < 2.8999999999999998e75

    1. Initial program 3.1

      \[\frac{x \cdot e^{\left(y \cdot \log z + \left(t - 1\right) \cdot \log a\right) - b}}{y} \]
    2. Simplified1.5

      \[\leadsto \color{blue}{e^{\left(y \cdot \log z + \left(t - 1\right) \cdot \log a\right) - b} \cdot \frac{x}{y}} \]
      Proof

      [Start]3.1

      \[ \frac{x \cdot e^{\left(y \cdot \log z + \left(t - 1\right) \cdot \log a\right) - b}}{y} \]

      rational.json-simplify-49 [=>]1.5

      \[ \color{blue}{e^{\left(y \cdot \log z + \left(t - 1\right) \cdot \log a\right) - b} \cdot \frac{x}{y}} \]
  3. Recombined 2 regimes into one program.
  4. Final simplification1.2

    \[\leadsto \begin{array}{l} \mathbf{if}\;x \leq -5 \cdot 10^{-33}:\\ \;\;\;\;\frac{\frac{e^{y \cdot \log z + \left(\left(t + -1\right) \cdot \log a - b\right)}}{y}}{\frac{1}{x}}\\ \mathbf{elif}\;x \leq 2.9 \cdot 10^{+75}:\\ \;\;\;\;e^{\left(y \cdot \log z + \left(t - 1\right) \cdot \log a\right) - b} \cdot \frac{x}{y}\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{e^{y \cdot \log z + \left(\left(t + -1\right) \cdot \log a - b\right)}}{y}}{\frac{1}{x}}\\ \end{array} \]

Alternatives

Alternative 1
Error1.0
Cost26692
\[\begin{array}{l} t_1 := y \cdot \log z\\ t_2 := \left(t - 1\right) \cdot \log a\\ \mathbf{if}\;\log a \leq -75:\\ \;\;\;\;\frac{x \cdot e^{\left(t_1 + t_2\right) - b}}{y}\\ \mathbf{else}:\\ \;\;\;\;x \cdot \frac{e^{t_1 + \left(t_2 - b\right)}}{y}\\ \end{array} \]
Alternative 2
Error1.2
Cost20424
\[\begin{array}{l} t_1 := \left(t - 1\right) \cdot \log a\\ t_2 := y \cdot \log z\\ t_3 := x \cdot \frac{e^{t_2 + \left(t_1 - b\right)}}{y}\\ \mathbf{if}\;x \leq -4 \cdot 10^{-33}:\\ \;\;\;\;t_3\\ \mathbf{elif}\;x \leq 2.9 \cdot 10^{+75}:\\ \;\;\;\;e^{\left(t_2 + t_1\right) - b} \cdot \frac{x}{y}\\ \mathbf{else}:\\ \;\;\;\;t_3\\ \end{array} \]
Alternative 3
Error2.4
Cost20420
\[\begin{array}{l} \mathbf{if}\;\left(t - 1\right) \cdot \log a \leq -600:\\ \;\;\;\;x \cdot \frac{{a}^{\left(t - 1\right)}}{y}\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{\frac{e^{y \cdot \log z - b}}{y}}{a}}{\frac{1}{x}}\\ \end{array} \]
Alternative 4
Error4.2
Cost20292
\[\begin{array}{l} \mathbf{if}\;\left(t - 1\right) \cdot \log a \leq -500:\\ \;\;\;\;x \cdot \frac{{a}^{\left(t - 1\right)}}{y}\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{x}{y}}{\frac{a}{e^{y \cdot \log z - b}}}\\ \end{array} \]
Alternative 5
Error2.3
Cost20160
\[x \cdot \frac{e^{y \cdot \log z + \left(\left(t - 1\right) \cdot \log a - b\right)}}{y} \]
Alternative 6
Error8.0
Cost13768
\[\begin{array}{l} t_1 := \frac{{z}^{y}}{a} \cdot \frac{x}{y}\\ \mathbf{if}\;y \leq -2.15 \cdot 10^{+99}:\\ \;\;\;\;t_1\\ \mathbf{elif}\;y \leq 1.08 \cdot 10^{+50}:\\ \;\;\;\;x \cdot \frac{e^{\left(t - 1\right) \cdot \log a - b}}{y}\\ \mathbf{else}:\\ \;\;\;\;t_1\\ \end{array} \]
Alternative 7
Error7.1
Cost13768
\[\begin{array}{l} \mathbf{if}\;y \leq -3.6 \cdot 10^{+98}:\\ \;\;\;\;\frac{{z}^{y}}{a} \cdot \frac{x}{y}\\ \mathbf{elif}\;y \leq 3 \cdot 10^{+80}:\\ \;\;\;\;x \cdot \frac{e^{\left(t - 1\right) \cdot \log a - b}}{y}\\ \mathbf{else}:\\ \;\;\;\;\frac{e^{y \cdot \log z - b}}{a \cdot \frac{y}{x}}\\ \end{array} \]
Alternative 8
Error11.9
Cost13576
\[\begin{array}{l} \mathbf{if}\;b \leq 5.2 \cdot 10^{-265}:\\ \;\;\;\;x \cdot \frac{{a}^{\left(t - 1\right)}}{y}\\ \mathbf{elif}\;b \leq 3.3 \cdot 10^{-21}:\\ \;\;\;\;\frac{{z}^{y}}{a} \cdot \frac{x}{y}\\ \mathbf{else}:\\ \;\;\;\;\frac{e^{\left(-\log a\right) - b} \cdot x}{y}\\ \end{array} \]
Alternative 9
Error11.5
Cost7308
\[\begin{array}{l} t_1 := x \cdot \frac{{a}^{\left(t - 1\right)}}{y}\\ \mathbf{if}\;b \leq 4.4 \cdot 10^{-262}:\\ \;\;\;\;t_1\\ \mathbf{elif}\;b \leq 2.6 \cdot 10^{-66}:\\ \;\;\;\;\frac{{z}^{y}}{a} \cdot \frac{x}{y}\\ \mathbf{elif}\;b \leq 460:\\ \;\;\;\;t_1\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{x}{e^{b}}}{y}\\ \end{array} \]
Alternative 10
Error22.7
Cost7248
\[\begin{array}{l} t_1 := \frac{\frac{x}{y}}{a}\\ \mathbf{if}\;b \leq -3.2 \cdot 10^{-17}:\\ \;\;\;\;x \cdot \left(\frac{2}{y \cdot \left(a \cdot \left(a + a\right)\right)} \cdot a\right)\\ \mathbf{elif}\;b \leq -6.5 \cdot 10^{-77}:\\ \;\;\;\;t_1\\ \mathbf{elif}\;b \leq -5.3 \cdot 10^{-276}:\\ \;\;\;\;x \cdot \left(a \cdot \frac{\frac{1}{a}}{a \cdot y}\right)\\ \mathbf{elif}\;b \leq 110:\\ \;\;\;\;t_1\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{x}{e^{b}}}{y}\\ \end{array} \]
Alternative 11
Error10.4
Cost7044
\[\begin{array}{l} \mathbf{if}\;b \leq 380:\\ \;\;\;\;x \cdot \frac{{a}^{\left(t - 1\right)}}{y}\\ \mathbf{else}:\\ \;\;\;\;\frac{\frac{x}{e^{b}}}{y}\\ \end{array} \]
Alternative 12
Error35.9
Cost1360
\[\begin{array}{l} t_1 := \frac{1}{a \cdot \frac{y}{x}}\\ t_2 := x \cdot \left(\frac{2}{y \cdot \left(a \cdot \left(a + a\right)\right)} \cdot a\right)\\ \mathbf{if}\;x \leq -1.02 \cdot 10^{-32}:\\ \;\;\;\;t_2\\ \mathbf{elif}\;x \leq -1.85 \cdot 10^{-229}:\\ \;\;\;\;t_1\\ \mathbf{elif}\;x \leq 7.5 \cdot 10^{-254}:\\ \;\;\;\;\frac{1}{\frac{y}{\frac{x}{a}}}\\ \mathbf{elif}\;x \leq 4.2 \cdot 10^{-32}:\\ \;\;\;\;t_1\\ \mathbf{else}:\\ \;\;\;\;t_2\\ \end{array} \]
Alternative 13
Error35.9
Cost1360
\[\begin{array}{l} t_1 := \frac{1}{a \cdot \frac{y}{x}}\\ t_2 := x \cdot \left(\frac{2}{y \cdot \left(a \cdot \left(a + a\right)\right)} \cdot a\right)\\ \mathbf{if}\;x \leq -3.1 \cdot 10^{-32}:\\ \;\;\;\;t_2\\ \mathbf{elif}\;x \leq -1.8 \cdot 10^{-289}:\\ \;\;\;\;t_1\\ \mathbf{elif}\;x \leq 7.5 \cdot 10^{-254}:\\ \;\;\;\;\frac{\left(\frac{-1}{b} + 1\right) \cdot \left(\frac{x}{a} \cdot \left(-b\right)\right)}{y}\\ \mathbf{elif}\;x \leq 2.6 \cdot 10^{-32}:\\ \;\;\;\;t_1\\ \mathbf{else}:\\ \;\;\;\;t_2\\ \end{array} \]
Alternative 14
Error37.3
Cost1232
\[\begin{array}{l} t_1 := \frac{1}{a \cdot \frac{y}{x}}\\ t_2 := x \cdot \left(a \cdot \frac{\frac{1}{a}}{a \cdot y}\right)\\ \mathbf{if}\;x \leq -3.2 \cdot 10^{+87}:\\ \;\;\;\;t_2\\ \mathbf{elif}\;x \leq -2.4 \cdot 10^{-228}:\\ \;\;\;\;t_1\\ \mathbf{elif}\;x \leq 1.1 \cdot 10^{-253}:\\ \;\;\;\;\frac{1}{\frac{y}{\frac{x}{a}}}\\ \mathbf{elif}\;x \leq 4 \cdot 10^{-15}:\\ \;\;\;\;t_1\\ \mathbf{else}:\\ \;\;\;\;t_2\\ \end{array} \]
Alternative 15
Error38.7
Cost976
\[\begin{array}{l} t_1 := \frac{1}{a \cdot \frac{y}{x}}\\ t_2 := \frac{x}{y \cdot a}\\ \mathbf{if}\;x \leq -2 \cdot 10^{+42}:\\ \;\;\;\;t_2\\ \mathbf{elif}\;x \leq -1.32 \cdot 10^{-265}:\\ \;\;\;\;t_1\\ \mathbf{elif}\;x \leq 3.6 \cdot 10^{-249}:\\ \;\;\;\;\frac{\frac{x}{a}}{y}\\ \mathbf{elif}\;x \leq 10^{-20}:\\ \;\;\;\;t_1\\ \mathbf{else}:\\ \;\;\;\;t_2\\ \end{array} \]
Alternative 16
Error38.7
Cost976
\[\begin{array}{l} t_1 := \frac{1}{a \cdot \frac{y}{x}}\\ t_2 := \frac{x}{y \cdot a}\\ \mathbf{if}\;x \leq -2 \cdot 10^{+38}:\\ \;\;\;\;t_2\\ \mathbf{elif}\;x \leq -1.7 \cdot 10^{-229}:\\ \;\;\;\;t_1\\ \mathbf{elif}\;x \leq 9 \cdot 10^{-254}:\\ \;\;\;\;\frac{1}{\frac{y}{\frac{x}{a}}}\\ \mathbf{elif}\;x \leq 2 \cdot 10^{-20}:\\ \;\;\;\;t_1\\ \mathbf{else}:\\ \;\;\;\;t_2\\ \end{array} \]
Alternative 17
Error39.4
Cost848
\[\begin{array}{l} t_1 := \frac{\frac{x}{y}}{a}\\ t_2 := \frac{x}{y \cdot a}\\ \mathbf{if}\;x \leq -3.7 \cdot 10^{+95}:\\ \;\;\;\;t_2\\ \mathbf{elif}\;x \leq -5.5 \cdot 10^{-228}:\\ \;\;\;\;t_1\\ \mathbf{elif}\;x \leq 8 \cdot 10^{-242}:\\ \;\;\;\;\frac{\frac{x}{a}}{y}\\ \mathbf{elif}\;x \leq 4 \cdot 10^{+32}:\\ \;\;\;\;t_1\\ \mathbf{else}:\\ \;\;\;\;t_2\\ \end{array} \]
Alternative 18
Error39.6
Cost840
\[\begin{array}{l} \mathbf{if}\;y \leq 1.7 \cdot 10^{-303}:\\ \;\;\;\;\frac{1}{a \cdot \frac{y}{x}}\\ \mathbf{elif}\;y \leq 5.5 \cdot 10^{-6}:\\ \;\;\;\;\frac{\frac{1}{y}}{\frac{a}{x}}\\ \mathbf{else}:\\ \;\;\;\;-1 \cdot \left(x \cdot \frac{b}{a \cdot y}\right)\\ \end{array} \]
Alternative 19
Error40.9
Cost452
\[\begin{array}{l} \mathbf{if}\;a \leq 7.4 \cdot 10^{-59}:\\ \;\;\;\;\frac{x}{y}\\ \mathbf{else}:\\ \;\;\;\;\frac{x}{y \cdot a}\\ \end{array} \]
Alternative 20
Error54.7
Cost192
\[\frac{x}{y} \]

Error

Reproduce?

herbie shell --seed 2023063 
(FPCore (x y z t a b)
  :name "Numeric.SpecFunctions:incompleteBetaWorker from math-functions-0.1.5.2, A"
  :precision binary64

  :herbie-target
  (if (< t -0.8845848504127471) (/ (* x (/ (pow a (- t 1.0)) y)) (- (+ b 1.0) (* y (log z)))) (if (< t 852031.2288374073) (/ (* (/ x y) (pow a (- t 1.0))) (exp (- b (* (log z) y)))) (/ (* x (/ (pow a (- t 1.0)) y)) (- (+ b 1.0) (* y (log z))))))

  (/ (* x (exp (- (+ (* y (log z)) (* (- t 1.0) (log a))) b))) y))