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SUBROUTINE FITVBV (MD, NCP, NDP, XD, YD, ZD, NIP,
X XI, YI, ZI, IWK, WK, IERROR)
C$ (ALG526 - Irregular Bivariate Interpolation)
C$ This subroutine performs bivariate interpolation when the
C$ projections of the data points in the X-Y plane are
C$ irregularly distributed in the plane. The input parameters
C$ are
C$
C$ MD.............Mode of computation (must be 1, 2, or 3),
C$ = 1 for new NCP and/or new XD-YD,
C$ = 2 for old NCP, old XD-YD, new XI-YI,
C$ = 3 for old NCP, old XD-YD, old XI-YI,
C$ NCP............Number of additional data points used for
C$ estimating partial derivatives at each data
C$ point (must be 2 or greater, but smaller
C$ than NDP),
C$ NDP............Number of data points (must be 4 or greater),
C$ XD(*)..........Array of dimension NDP containing the X
C$ coordinates of the data points,
C$ YD(*)..........Array of dimension NDP containing the Y
C$ coordinates of the data points,
C$ ZD(*)..........Array of dimension NDP containing the Z
C$ coordinates of the data points,
C$ NIP............Number of output points at which
C$ interpolation is to be performed (must be 1
C$ or greater),
C$ XI(*)..........Array of dimension NIP containing the X
C$ coordinates of the output points,
C$ YI(*)..........Array of dimension NIP containing the Y
C$ coordinates of the output points.
C$
C$ The output parameters are
C$
C$ ZI(*)..........Array of dimension NIP where interpolated Z
C$ values are to be stored.
C$ IERROR.........0 (Normal return)
C$ 1 (Abnormal return. A message will be
C$ printed giving all the arguments, and
C$ nothing more will be done)
C$
C$ The other parameters are:
C$
C$ IWK(*).........INTEGER array of dimension
C$ MAX0(31,27+NCP)*NDP+NIP used internally as a
C$ work area,
C$ WK(*)..........Array of dimension 8*NDP used internally as
C$ a work area.
C$
C$ The very first call to this subroutine and the call with a
C$ new NCP value, a new NDP value, and/or new contents of the
C$ XD and YD arrays must be made with MD=1. The call with
C$ MD=2 must be preceded by another call with the same NCP and
C$ NDP values and with the same contents of the XD and YD
C$ arrays. The call with MD=3 must be preceded by another
C$ call with the same NCP, NDP, and NIP values and with the
C$ same contents of the XD, YD, XI, and YI arrays. Between
C$ the call with MD=2 or MD=3 and its preceding call, the IWK
C$ and WK arrays must not be disturbed. Use of a value
C$ between 3 and 5 (inclusive) for NCP is recommended unless
C$ there are evidences that dictate otherwise.
C$
C$ This subroutine calls the FITVCL, FITVLC, FITVPD, FITVPT,
C$ and FITVTA subroutines.
C$
C$ This routine incorporates the corrections published in
C$ Hiroshi Akima, "Remark on Algorithm 526", ACM Trans. Math.
C$ Software 5, No. 2, 242-243 (June 1979).
C$
C$ (03-APR-82)