f <I>r</I>.
<P>
<I>ldfjac</I> is a positive integer input variable not less than
<I>m</I> which specifies the leading dimension of the array
<I>fjac</I>.
<P>
<I>ipvt</I> is an integer output array of length <I>n</I>. <I>ipvt</I>
defines a permutation matrix <I>p</I> such that <I>jac</I>*<I>p</I> =
<I>q</I>*<I>r</I>, where <I>jac</I> is the final calculated Jacobian,
<I>q</I> is orthogonal (not stored), and <I>r</I> is upper triangular
with diagonal elements of nonincreasing magnitude.  Column <B>j</B>
of <I