Function:     GAUESTD

Purpose:      Searches for gaussian components in a profile.

Category:     MATH

File:         gauestd.c

Author:       K.G. Begeman

Use:          INTEGER GAUESTD( Y ,      Input     DOUBLE PRECISION ARRAY
                               WORK ,   Output    DOUBLE PRECISION ARRAY
                               N ,      Input     INTEGER
                               P ,      Output    DOUBLE PRECISION ARRAY
                               NP ,     Input     INTEGER
                               RMS ,    Input     DOUBLE PRECISION
                               CUTAMP , Input     DOUBLE PRECISION
                               CUTSIG , Input     DOUBLE PRECISION
                               Q )      Input     INTEGER

              GAUESTD       Returns number of gaussians found.
              Y             Data points on profile (dimension N).
              WORK          Work array (dimension N).
              N             Number of points in profile (dimension
                            of Y and WORK).
              P             Contains the estimated gaussian parameters
                            on output. The dimension of P should be at
                            least NP. Each gaussian takes three elements
                            of P to store the parameters. First the
                            amplitude, then the centre and third the
                            dispersion. The dispersion is in units of
                            pixels, to get the dispersion in physical
                            units multiply by the grid separation.
                            The centre is in units of pixel offset
                            (relative to first pixel in Y).
              NP            Maximum number of parameters which can be
                            stored in P, i.e. the maximum number of
                            gaussian components, multiplied by 3.
              RMS           The  r.m.s. noise level of the profile.
              CUTAMP        Critical amplitude of gaussian. Gaussians
                            below this amplitude will be discarded.
              CUTSIG        Critical dispersion of gaussian.
              Q             Smoothing parameter used in calculating the
                            second derivative of the profile. Q must be
                            greater than zero.

Description:  Double precision version of gauest, using the entire 
              profile as signal region.  The second derivative of
              the profile in the signal region is calculated by fitting
              a second degree polynomal. The smoothing parameter Q
              determines the number of points used for this (=2*Q+1).
              The gaussians can then be estimated as described by
              Schwarz, 1968, Bull.Astr.Inst.Netherlands, Volume 19, 405.

Updates:      Mar 12, 1991: KGB Document created.
              Jul 08, 1999: VOG Double precision version. Window method
                                removed. 
              Nov  8, 2010: JPT Corrected documentation for arguments P and NP.