This function computes the cumulative probability or nonexceedance probability of the Slash distribution given parameters (\(\xi\) and \(\alpha\)) of the distribution provided by parsla
or vec2par
. The cumulative distribution function is
$$F(x) = \Phi(Y) - [\phi(0) - \phi(Y)]/Y \mbox{,}$$
for \(Y \ne 0\) and
$$F(x) = 1/2 \mbox{,}$$
for \(Y = 0\), where \(f(x)\) is the probability density for quantile \(x\), \(Y = (x - \xi)/\alpha\), \(\xi\) is a location parameter, and \(\alpha\) is a scale parameter. The function \(\Phi(Y)\) is the cumulative distribution function of the Standard Normal distribution function, and \(\phi(Y)\) is the probability density function of the Standard Normal distribution.