1IDSFFT(3NCARG) NCAR GRAPHICS IDSFFT(3NCARG)
2
6 IDSFFT - Performs smooth surface fitting when the projections of the
7 data points in the X-Y plane are irregularly distributed in the plane.
8
10 CALL IDSFFT (MD, NDP, XD, YD, ZD, MREG, NREG, KREG,
11 + XREG, YREG, ZREG, IWK, WK)
12
14 #include <ncarg/ncargC.h>
15 void c_idsfft (int md, int ndp, float *xd, float *yd,
17 float *zd, int mreg, int nreg, int kreg, float *xreg,
18 float *yreg, float *zreg, int *iwk, float *wk)
19
21 MD (Integer, Input/output) - Mode of computation (must be 1,
22 2, or 3).
23 1 If this is the first call to this subroutine, or if
25 the value of NDP has been changed from the previous
26 call, or if the contents of the XD or YD arrays have
27 been changed from the previous call.
28 2 If the values of NDP and the XD, YD arrays are
30 unchanged from the previous call, but new values for
31 XREG, YREG are being used. If MD=2 and NDP has been
32 changed since the previous call to IDSFFT, an error
33 return occurs.
34 3 If the values of NDP, MREG, NREG, XD, YD, XREG, YREG
36 are unchanged from the previous call, that is, if
37 the only change on input to IDSFFT is in the ZD
38 array. If MD=3 and NDP, MREG or NREG has been
39 changed since the previous call to IDSFFT, an error
40 return occurs.
41 Between the call with MD=2 or MD=3 and the preceding
43 call, the IWK and WK work arrays should not be
44 disturbed.
45 NDP (Integer, Input) - Number of random data points (must be 4
47 or greater).
48 XD(NDP) (Real array, Input) - Array of dimension NDP containing the
50 X coordinates of the data points.
51 YD(NDP) (Real array, Input) - Array of dimension NDP containing the
53 Y coordinates of the data points.
54 ZD(NDP) (Real array, Input) - Array of dimension NDP containing the
56 Z coordinates of the data points.
57 MREG (Integer, Input) - Number of output grid points in the X-
59 direction (must be 1 or greater).
60 NREG (Integer, Input) - Number of output grid points in the Y-
62 direction (must be 1 or greater).
63 KREG (Integer, Input) - First dimension of ZREG as declared in
65 the calling program. KREG must be greater than or equal to
66 MREG, else an error return occurs.
67 XREG(MREG) (Real array, Input) - Array of dimension MREG containing
69 the X coordinates of the output grid points.
70 YREG(NREG) (Real array, Input) - Array of dimension NREG containing
72 the Y coordinates of the output grid points.
73 ZREG(KREG,NREG)
75 (Real array, Output) - Real, two-dimensional array of
76 dimension (KREG,NREG), storing the interpolated Z values at
77 the output grid points.
78 IWK(*) (Integer array, Workspace) - Integer work array of
80 dimension at least 31 * NDP + MREG * NREG.
81 WK(*) (Real array, Workspace) - Real work array of dimension at
83 least 6 * NDP.
84 Inadequate work space IWK and WK may may cause incorrect results.
87 The data points must be distinct and their projections in the X-Y plane
89 must not be collinear; otherwise, an error return occurs.
90
92 The C-binding argument descriptions are the same as the FORTRAN
93
95 To use IDSFFT routines, load the NCAR Graphics libraries ncarg,
96 ncarg_gks, and ncarg_c, preferably in that order.
97 Use the ncargex command to see the following relevant examples:
99 ccpcldm, ccpfil, ccplbam, ccpllb, ccpllc, ccplll, ccpllo, ccpllp,
100 ccpllt, ccpllw, ccpnet, ccppc, ccppc1, ccppc2, ccppc3, ccppc4, ccprc,
101 ccpscam, cidsfft, fsfsgfa, cbex01.
102
104 To use IDSFFT or c_idsfft, load the NCAR Graphics libraries ncarg,
105 ncarg_gks, and ncarg_c, preferably in that order.
106
108 See the bivar man page for a description of all Bivar error messages
109 and/or informational messages.
110
112 Online: bivar, bivar_params, idbvip, idpltr, idgeti, idgetr, idseti,
113 idsetr, ncarg_cbind
114 Hardcopy: NCAR Graphics Contouring and Mapping Tutorial
116
118 Bivar was written by Hiroshi Akima in August 1975 and rewritten by him
119 in late 1976. In 1989, a new version of Bivar, incorporating changes
120 described in a Rocky Mountain Journal of Mathematics was obtained from
121 Dr. Akima, and included in NCAR Graphics with his permission. In 1995,
122 Dave Kennison incorporated the capability of doing linear interpolation
123 and a different kind of triangulation, put in a parameter access
124 interface, and wrote a routine to allow the triangulation to be
125 plotted.
126
128 Copyright (C) 1987-2007
129 University Corporation for Atmospheric Research
130 This documentation is free software; you can redistribute it and/or
132 modify it under the terms of the GNU General Public License as
133 published by the Free Software Foundation; either version 2 of the
134 License, or (at your option) any later version.
135 This software is distributed in the hope that it will be useful, but
137 WITHOUT ANY WARRANTY; without even the implied warranty of
138 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
139 General Public License for more details.
140 You should have received a copy of the GNU General Public License along
142 with this software; if not, write to the Free Software Foundation,
143 Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
144UNIX November 1995 IDSFFT(3NCARG)