Provided by: libncarg-dev_6.4.0-9_amd64

**NAME**

Bivar - Provides bivariate interpolation and smooth surface fitting for values given at irregularly distributed points. The resulting interpolating function and its first-order partial derivatives are continuous. The method employed is local, i.e. a change in the data in one area of the plane does not affect the interpolating function except in that local area. Also, the method gives exact results when all points lie in a plane.

**SYNOPSIS**

IDBVIP Produces interpolated values at points (XI(I), YI(I)), I=1,...,NIP. This is useful for filling in missing data points on a grid. IDSFFT Performs smooth surface fitting when the projections of the data points in the X-Y plane are irregularly distributed in the plane. IDPLTR Plots the triangulation of the data points. IDGETI Retrieves the integer value of a Bivar parameter. IDGETR Retrieves the real value of a Bivar parameter. IDSETI Provides a new integer value for a Bivar parameter. IDSETR Provides a new real value for a Bivar parameter.

**C-BINDING** **SYNOPSIS**

c_idbvip, c_idsfft c_idpltr c_idgeti c_idgetr c_idseti c_idsetr

**EXAMPLES**

See the example "cbex01".

**ACCESS**

To use the Bivar Fortran or C routines, load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably in that order.

**MESSAGES**

When error conditions are detected, the support routine SETER is called. By default, SETER writes a message to the standard error file (as defined by I1MACH(4)) and then terminates execution. It is possible to put SETER into recovery mode and regain control after a recoverable error (which includes all of the possible errors). The possible error messages are listed below. All errors are recoverable in the sense that a user program which has called ENTSR to set recovery mode will get control back after one of these errors occurs. IDBVIP (BIVAR) - UNCLEARED PRIOR ERROR IDBVIP (BIVAR) - INPUT VARIABLE MD IS OUT OF RANGE IDBVIP (BIVAR) - INPUT VARIABLE NDP IS OUT OF RANGE IDBVIP (BIVAR) - INPUT VARIABLE NIP IS OUT OF RANGE IDBVIP (BIVAR) - MD = 2 OR 3 BUT NDP WAS CHANGED SINCE LAST CALL IDBVIP (BIVAR) - MD = 3 BUT ITY WAS CHANGED SINCE LAST CALL IDBVIP (BIVAR) - MD = 3 BUT NIP WAS CHANGED SINCE LAST CALL IDGETI (BIVAR) - UNCLEARED PRIOR ERROR IDGETR (BIVAR) - UNCLEARED PRIOR ERROR IDGETR (BIVAR) - INVALID KEYWORD: xxx IDGRID (BIVAR) - INTERNAL ERROR - SEE CONSULTANT IDPLTR (BIVAR) - UNCLEARED PRIOR ERROR IDSETI (BIVAR) - UNCLEARED PRIOR ERROR IDSETR (BIVAR) - UNCLEARED PRIOR ERROR IDSETR (BIVAR) - INVALID KEYWORD: xxx IDSFFT (BIVAR) - UNCLEARED PRIOR ERROR IDSFFT (BIVAR) - INPUT VARIABLE MD IS OUT OF RANGE IDSFFT (BIVAR) - INPUT VARIABLE NDP IS OUT OF RANGE IDSFFT (BIVAR) - INPUT VARIABLE NXI OR NYI IS OUT OF RANGE IDSFFT (BIVAR) - INPUT VARIABLE NZI IS LESS THAN NXI IDSFFT (BIVAR) - MD = 2 OR 3 BUT NDP WAS CHANGED SINCE LAST CALL IDSFFT (BIVAR) - MD = 3 BUT ITY WAS CHANGED SINCE LAST CALL IDSFFT (BIVAR) - MD = 3 BUT NXI WAS CHANGED SINCE LAST CALL IDSFFT (BIVAR) - MD = 3 BUT NYI WAS CHANGED SINCE LAST CALL IDTANG (BIVAR) - INPUT PARAMETER NDP OUT OF RANGE IDTANG (BIVAR) - TWO OF THE INPUT DATA POINTS ARE IDENTICAL IDTANG (BIVAR) - ALL COLLINEAR DATA POINTS

**SEE** **ALSO**

Online: bivar_params, idbvip, idsfft, idpltr, idgeti, idgetr, idseti, idsetr, ncarg_cbind Hardcopy: NCAR Graphics Contouring and Mapping Tutorial; NCAR Graphics Fundamentals, UNIX Version

**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.