utine NF01AY. The parameter
  vector X is partitioned as X = ( wb(1), ..., wb(L), theta ),
  where wb(i), i = 1 : L, correspond to the nonlinear part, and
  theta corresponds to the linear part. See SLICOT Library routine
  NF01AD for further details.

  The sum of squares of the error functions, defined by

     e(t) = y(t) - Y(t),  t = 1, 2, ..., NSMP,

  is minimized, where Y(t) is the measured output vector. The
  functions and their Jacobian matrices are evaluated by SLICOT
  Library routine NF01BB (th