suitable
step length for the forward-difference approximation. This
approximation assumes that the relative errors in the
functions are of the order of <I>epsfcn</I>. If <I>epsfcn</I> is less
than the machine precision, it is assumed that the relative
errors in the functions are of the order of the machine
precision.
<P>
<I>diag</I> is an array of length <I>n</I>. If <I>mode</I> = 1 (see
below), <I>diag</I> is internally set. If <I>mode</I> = 2, <I>diag</I>
must contain positive entries that serve as
multip