NAME

       IDSFFT - Performs smooth surface fitting when the projections of the data points in the X-Y plane are
       irregularly distributed in the plane.

SYNOPSIS

        CALL IDSFFT (MD, NDP, XD, YD, ZD, MREG, NREG, KREG,
       + XREG, YREG, ZREG, IWK, WK)

C-BINDING SYNOPSIS

       #include <ncarg/ncargC.h>

       void c_idsfft (int md, int ndp, float *xd, float *yd,
       float *zd, int mreg, int nreg, int kreg, float *xreg,
       float *yreg, float *zreg, int *iwk, float *wk)

DESCRIPTION

       MD          (Integer, Input/output) - Mode of computation (must be 1, 2, or 3).

                   1      If  this is the first call to this subroutine, or if the value of NDP has been changed
                          from the previous call, or if the contents of the XD or YD arrays  have  been  changed
                          from the previous call.

                   2      If  the  values of NDP and the XD, YD arrays are unchanged from the previous call, but
                          new values for XREG, YREG are being used. If MD=2 and NDP has been changed  since  the
                          previous call to IDSFFT, an error return occurs.

                   3      If  the  values of NDP, MREG, NREG, XD, YD, XREG, YREG are unchanged from the previous
                          call, that is, if the only change on input to IDSFFT is in the ZD array. If  MD=3  and
                          NDP,  MREG or NREG has been changed since the previous call to IDSFFT, an error return
                          occurs.

                          Between the call with MD=2 or MD=3 and the preceding call, the IWK and WK work  arrays
                          should not be disturbed.

       NDP         (Integer, Input) - Number of random data points (must be 4 or greater).

       XD(NDP)     (Real array, Input) - Array of dimension NDP containing the X coordinates of the data points.

       YD(NDP)     (Real array, Input) - Array of dimension NDP containing the Y coordinates of the data points.

       ZD(NDP)     (Real array, Input) - Array of dimension NDP containing the Z coordinates of the data points.

       MREG        (Integer, Input) - Number of output grid points in the X-direction (must be 1 or greater).

       NREG        (Integer, Input) - Number of output grid points in the Y-direction (must be 1 or greater).

       KREG        (Integer,  Input)  - First dimension of ZREG as declared in the calling program. KREG must be
                   greater than or equal to MREG, else an error return occurs.

       XREG(MREG)  (Real array, Input) - Array of dimension MREG containing the X coordinates of the output grid
                   points.

       YREG(NREG)  (Real array, Input) - Array of dimension NREG containing the Y coordinates of the output grid
                   points.

       ZREG(KREG,NREG)
                   (Real array, Output) - Real, two-dimensional array  of  dimension  (KREG,NREG),  storing  the
                   interpolated Z values at the output grid points.

       IWK(*)      (Integer array, Workspace) - Integer work array of dimension at least 31 * NDP + MREG * NREG.

       WK(*)       (Real array, Workspace) - Real work array of dimension at least 6 * NDP.

       Inadequate work space IWK and WK may may cause incorrect results.

       The data points must be distinct and their projections in the X-Y plane must not be collinear; otherwise,
       an error return occurs.

C-BINDING DESCRIPTION

       The C-binding argument descriptions are the same as the FORTRAN

EXAMPLES

       To  use  IDSFFT  routines,  load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably in
       that order.

       Use the ncargex command to see the following relevant examples: ccpcldm, ccpfil, ccplbam, ccpllb, ccpllc,
       ccplll, ccpllo, ccpllp, ccpllt, ccpllw, ccpnet, ccppc, ccppc1, ccppc2, ccppc3,  ccppc4,  ccprc,  ccpscam,
       cidsfft, fsfsgfa, cbex01.

ACCESS

       To  use IDSFFT or c_idsfft, load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably in
       that order.

MESSAGES

       See the bivar man page for a description of all Bivar error messages and/or informational messages.

SEE ALSO

       Online: bivar, bivar_params, idbvip, idpltr, idgeti, idgetr, idseti, idsetr, ncarg_cbind

       Hardcopy: NCAR Graphics Contouring and Mapping Tutorial

ACKNOWLEDGMENTS

       Bivar was written by Hiroshi Akima in August 1975 and rewritten by him in late  1976.   In  1989,  a  new
       version of Bivar, incorporating changes described in a Rocky Mountain Journal of Mathematics was obtained
       from  Dr.  Akima, and included in NCAR Graphics with his permission.  In 1995, Dave Kennison incorporated
       the capability of doing linear interpolation and a different kind of triangulation, put  in  a  parameter
       access interface, and wrote a routine to allow the triangulation to be plotted.

COPYRIGHT

       Copyright (C) 1987-2009
       University Corporation for Atmospheric Research
       The use of this Software is governed by a License Agreement.

UNIX                                              November 1995                                   IDSFFT(3NCARG)