br><br>
Alternatively, errors can be visualized using a sampling method. In
this method a number of curves is calculated with variations of the
parameter values, as sampled from a multi-variate Gaussian p.d.f. that
is constructed from the fit results covariance matrix.  The error(x)
is determined by calculating a central interval that capture N% of the
variations for each value of x, where N% is controlled by Z (i.e. Z=1
gives N=68%). The number of sampling curves is chosen to be such that
at least 100 curv