x^(8/9)

(FPCore (x) :precision binary64 (pow x (/ 8.0 9.0)))

double code(double x) {
	return pow(x, (8.0 / 9.0));
}

real(8) function code(x)
    real(8), intent (in) :: x
    code = x ** (8.0d0 / 9.0d0)
end function

public static double code(double x) {
	return Math.pow(x, (8.0 / 9.0));
}

def code(x):
	return math.pow(x, (8.0 / 9.0))

function code(x)
	return x ^ Float64(8.0 / 9.0)
end

function tmp = code(x)
	tmp = x ^ (8.0 / 9.0);
end

code[x_] := N[Power[x, N[(8.0 / 9.0), $MachinePrecision]], $MachinePrecision]

\begin{array}{l}

\\
{x}^{\left(\frac{8}{9}\right)}
\end{array}