function [ftrack, rtrack, itrack] = fit_the_track(tmm, xdd, fdd, rdd, idd)
//
//  [ftrack, rtrack, itrack] = fit_the_track(tmm, xdd, fdd, rdd, idd)
//
//  spline fit of the data
//
//  ------------------------------------------------------------------------
//  copyright 2007  Alfred Steffens Jr.
//  -----------------------------------------------------------------------
//  -----------------------------------------------------------------------
//  Copying Permission:
//
//    This is free software; you can redistribute it and/or modify
//    it under the terms of the GNU General Public License as published by
//    the Free Software Foundation.
//
//    This software is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU General Public License for more details.
//
//    You should have received a copy of the GNU General Public License
//    along with this software (see file called "COPYING"); if not, write to
//    the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
//    MA 02111-1307  USA
//  ------------------------------------------------------------------------

//
ydff = interpln([tmm' ; fdd'], xdd);        // 1st cut at curve
[yl, dl] = lsq_splin(xdd, ydff, tmm');
ftrack = interp(xdd, tmm', yl, dl);         // frequencies
ydrr = interpln([tmm' ; rdd'], xdd);        // 1st cut at curve
[yl, dl] = lsq_splin(xdd, ydrr, tmm');
rtrack = interp(xdd, tmm', yl, dl);         // real amplitudes
ydii = interpln([tmm' ; idd'], xdd);        // 1st cut at curve
[yl, dl] = lsq_splin(xdd, ydii, tmm');
itrack = interp(xdd, tmm', yl, dl);         // imag amplitudes

endfunction