assert_erfcond — Computes the condition number of the erf function.
[c,y] = assert_erfcond ( x )
a n-by-m matrix of doubles
a n-by-m matrix of doubles, the condition number
a n-by-m, matrix of doubles, the function values
Computes the condition number of the erf function. The erf function is always well conditionned, since its condition number is never greater than 1.
<latex> \begin{eqnarray} c(x) = \frac{2}{\sqrt{\pi}} \left| \frac{x\exp\left(-x^2\right)}{f(x)} \right| \end{eqnarray} </latex>
where
<latex> \begin{eqnarray} f(x) = \mbox{erf}(x) \end{eqnarray} </latex>