Name:          VOIGT              


Purpose:       DVOIGT computes the partial derivatives of a Voigt

Files:         voigt.dc2,voigt.shl

Author:        Peter Roelfsema


Call:

    CALL DVOIGT(X,PAR,DERIV,NPAR)          ( entry point in VOIGT )

Input parameters:
             X     -R   -running coordinate.
             PAR   -R   -array defined as follows: PAR(0:NPAR*4) that
                 contains the parameters for the Voigt in the following
                 order:

                         PAR(0)        -zerolevel
                    PAR(1)  -PAR(4)    -int, pos. of peak, gauss fwhm
                                        and lorentz fwhm of cmp. 1
                          .                     .
                  PAR(1+4*n)-PAR(4+4*n)-int, pos. of peak, gauss fwhm
                                        and lorentz fwhm of cmp. n-1
                                  etc

             NPAR  -I   -number of components.
Output parameters:
             DERIV -R   -array defined as follows: DERIV(0:NPAR*4) that
                 contains the partial derivatives in the following order:
                            DERIV(0)       -part.  deriv of zerolevel
                      DERIV(1)-DERIV(4)    -part.  derivs. of cmp. 1
                             .                     .
                  DERIV(1+4*n)-DERIV(4+4*n)-part.  derivs. of cmp. n-1
                                       etc


Use:
               DVOIGT gives the partial derivatives for the gaussian.
               Note that the Voigt components are defined in terms of
               their Intensity, centre coordinate and Full Widths at  Half
               Maximum ( i.e. not in terms of amplitude and sigma ! ).