Provided by: libncarg-dev_6.4.0-9_amd64 bug

NAME

       PCMPXY - This routine is normally not called directly by the user (though it can be). It
       is called by each of the routines PCHIQU, PCMEQU, and PCLOQU when the user has set the
       mapping flag ´MA´ nonzero to request mapping of characters from one X/Y coordinate system
       to another.

SYNOPSIS

       CALL PCMPXY (IMAP,XINP,YINP,XOTP,YOTP)

C-BINDING SYNOPSIS

       #include <ncarg/ncargC.h>
       void c_pcmpxy (int imap, float xinp, float yinp, float *xotp, float *yotp)

DESCRIPTION

       IMAP        (an input expression of type INTEGER) specifies which mapping is to be done.
                   Whenever Plotchar routines call PCMPXY, IMAP = ´MA´. The default version of
                   PCMPXY recognizes the following values of IMAP:

                   IMAP = 0

                          Type of mapping
                             None. When IMAP is zero, the routine PCMPXY is being asked for
                             information about its capabilities with respect to a particular
                             mapping.

                          XINP
                             Input: the real equivalent of a possible value of IMAP about which
                             information is desired.

                          YINP
                             Output (real): 0. says that the mapping specified by XINP is not
                             available, 1.  that it is available, 2. that its inverse is
                             available, and 3. that both it and its inverse are available.

                   IMAP = 1

                          Type of mapping
                             Ezmap projection.

                          XINP
                             Longitude, in degrees.

                          YINP
                             Latitude, in degrees.

                   IMAP = 2

                          Type of mapping
                             Rho/theta mapping.

                          XINP
                             Rho, in user units.

                          YINP
                             Theta, in degrees.

                   IMAP = 3

                          Type of mapping
                             Projection from an arbitrary parallelogram in 3-space to an image
                             plane. This is implemented using a package which is currently under
                             development and is not yet generally available.

                          XINP
                             A multiplier for a unit vector along one edge of the parallelogram.

                          YINP
                             A multiplier for a unit vector along an intersecting edge of the
                             parallelogram.

                   IMAP = 4

                          Type of mapping
                             A version of the EZMAP projection that is intended to be used to
                             label specific points on the surface of the globe.  When 'MA' = 4,
                             use "0." for each of the arguments XPOS, YPOS, and ANGD in calls to
                             PCHIQU and PCMEQU.  Initially, each label is assumed to be placed at
                             the point on the globe with latitude zero and longitude zero and to
                             be written along the equator.  Three rotations are then performed to
                             move the label to the point (PLAT,PLON) in such a way that it makes
                             an angle PANG with the local eastward-pointing vector.  Finally, the
                             EZMAP routine MAPTRA is called to project the label as specified by
                             the current state of EZMAP.  The desired values of PANG, PLAT, and
                             PLON (in degrees) are passed to PCMPXY in the labelled common block
                             PCMP04, which contains just those three variables, in that order.
                             Use the ncargex command to see the following relevant example:
                             cpex10.

                          XINP
                             Longitude, in degrees.

                          YINP
                             Latitude, in degrees.

                   IMAP = 100

                          Type of mapping
                             The identity mapping, but returns 1.E12 outside a specified
                             viewport. Used by the utility Scrolled_title to do clipping at the
                             edges of the viewport.

                          XINP
                             X coordinate, in the fractional system.

                          YINP
                             Y coordinate, in the fractional system.

                   other > 0

                          Type of mapping
                             The identity mapping.

                          XINP
                             Any real value.

                          YINP
                             Any real value.

                   other < 0

                          Type of mapping
                             An inverse mapping.

                          XINP
                             A mapped X coordinate.

                          YINP
                             A mapped Y coordinate.

                   Note: Values of IMAP less than or equal to zero are not currently used by
                   Plotchar in calling PCMPXY. The scheme described is the same as that used for
                   the routine CPMPXY, in the NCAR Graphics package Conpack. It is possible that,
                   in the future, values of IMAP less than or equal to zero will occur in calls
                   to PCMPXY, so it is best to be prepared.

       XINP and YINP
                   (input expressions of type REAL) specify the X and Y coordinates of a point to
                   be mapped.

                   Note: When IMAP is less than or equal to zero (which cannot currently happen,
                   but may someday be possible), XINP and YINP are used differently, as shown
                   above.

       XOTP and YOTP
                   (output variables of type REAL) in which PCMPXY returns the mapped X and Y
                   coordinates of the point.  If the point is not visible under the mapping
                   selected (as, for example, when the orthographic projection of Ezmap is being
                   used and the point to be mapped is on the other side of the globe), PCMPXY
                   must return, as a signal that this is the case, whatever special nonzero value
                   has been given to the internal parameter ´OR´, so that the calling routine can
                   take appropriate action (to properly clip the character being drawn, for
                   example).

                   Note: When IMAP is less than or equal to zero (which cannot currently happen,
                   but may someday be possible), XOTP and YOTP are used differently, as shown in
                   the table above.

C-BINDING DESCRIPTION

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

USAGE

       This routine is normally not called directly by the user (though it can be). It is called
       by each of the routines PCHIQU, PCMEQU, and PCLOQU when the user has set the mapping flag
       ´MA´ nonzero to request mapping of characters from one X/Y coordinate system to another. A
       call to PCMPXY has the following form:

            CALL PCMPXY (IMAP,XINP,YINP,XOTP,YOTP)

       The default version of PCMPXY does several useful mappings; a user version may be supplied
       to do others.

ACCESS

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

SEE ALSO

       Online: plotchar, pcdlsc, pcgetc, pcgeti, pcgetr, pchiqu, pcloqu, pcmequ, pcpnwi, pcrset,
       pcsetc, pcseti, pcsetr, ncarg_cbind.

       Hardcopy: NCAR Graphics Fundamentals, UNIX Version

COPYRIGHT

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