1CPMPXY(3NCARG)                   NCAR GRAPHICS                  CPMPXY(3NCARG)
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NAME

6       CPMPXY - Maps Conpack output from a rectangular coordinate system
7       superimposed on the data grid to some other coordinate system.
8

SYNOPSIS

10       CALL CPMPXY (IMAP, XINP, YINP, XOTP, YOTP)
11

DESCRIPTION

13       IMAP        (INTEGER, input) is zero if the object of the call is to
14                   ask CPMPXY about its mapping capabilities, greater than
15                   zero if the object of the call is to do a forward mapping,
16                   and less than zero if the object of the call is to do an
17                   inverse mapping. When IMAP is non-zero, its absolute value
18                   matches the current value of the parameter 'MAP' and
19                   identifies the mapping to be used.
20
21       XINP        (REAL, input) is used in one of three ways:
22
23                   ·   When IMAP is zero, the value INT(XINP) is the index of
24                       a mapping about which CPMPXY is being asked to supply
25                       information.
26
27                   ·   When IMAP is greater than zero, XINP is the X
28                       coordinate of a point on the contour plot. If 'XC1' =
29                       'XCM' (the default situation), then XINP will lie in
30                       the range from 1 to M, where M is the first dimension
31                       of the array being contoured (equal to the value of the
32                       parameter 'ZDM'); in this case, the X coordinate will
33                       have the same range as the first index of the data
34                       array. If the user sets 'XC1' unequal to 'XCM', then
35                       XINP will lie in the range from 'XC1' (corresponding to
36                       an index value of 1) to 'XCM' (corresponding to an
37                       index value of M).
38
39                   ·   When IMAP is less than zero, XINP is the X coordinate
40                       of a point on the contour plot, in a coordinate system
41                       consistent with the current window, as specified by
42                       arguments 5 through 8 of the last call to the SPPS
43                       routine SET or by the equivalent call to GKS.
44
45       YINP        (REAL, input/output) is used in one of three ways:
46
47                   ·      When IMAP is zero, CPMPXY is expected to return one
48                          of the following values of YINP: YINP = 0. indicates
49                          that neither the forward nor the inverse
50                          transformation is defined. YINP = 1. indicates that
51                          the forward transformation is defined, but the
52                          inverse is not. YINP = 2. indicates that the forward
53                          transformation is not defined, but the inverse is.
54                          YINP = 3. indicates that both the forward and the
55                          inverse transformations are defined.
56
57                   ·      When IMAP is greater than zero, YINP is the Y
58                          coordinate of a point on the contour plot. If 'YC1'
59                          = 'YCN' (the default situation), then YINP will lie
60                          in the range from 1 to N, where N is the second
61                          dimension of the array being contoured (equal to the
62                          value of the parameter 'ZDN'); in this case, the Y
63                          coordinate will have the same range as the second
64                          index of the data array. If the user sets 'YC1'
65                          unequal to 'YCN', then YINP will lie in the range
66                          from 'YC1' (corresponding to an index value of 1) to
67                          'YCN' (corresponding to an index value of N).
68
69                   ·      When IMAP is less than zero, YINP is the Y
70                          coordinate of a point on the contour plot, in a
71                          coordinate system consistent with the current
72                          window, as specified by arguments 5 through 8 of the
73                          last call to the SPPS routine SET or by the
74                          equivalent call to GKS.
75
76       XOTP and YOTP
77                   (REAL, output) are used in one of two ways:
78
79                   ·      If IMAP is greater than zero, XOTP and YOTP are the
80                          X and Y coordinates of a point on the contour plot,
81                          in a coordinate system consistent with the current
82                          window, as specified by arguments 5 through 8 of the
83                          last call to the SPPS routine SET or by the
84                          equivalent call to GKS.
85
86                   ·      When IMAP is less than zero, XOTP and YOTP are the X
87                          and Y coordinates of a point on the contour plot. If
88                          'XC1' = 'XCM' (the default situation), then XOTP
89                          will lie in the range from 1 to M, where M is the
90                          first dimension of the array being contoured (equal
91                          to the value of the parameter 'ZDM'); in this case,
92                          the X coordinate will have the same range as the
93                          first index of the data array. If the user sets
94                          'XC1' unequal to 'XCM', then XOTP will lie in the
95                          range from 'XC1' (corresponding to an index value of
96                          1) to 'XCM' (corresponding to an index value of M).
97                          Similarly, if 'YC1' = 'YCN' (the default situation),
98                          then YOTP will lie in the range from 1 to N, where N
99                          is the second dimension of the array being contoured
100                          (equal to the value of the parameter 'ZDN'); in this
101                          case, the Y coordinate will have the same range as
102                          the second index of the data array. If the user sets
103                          'YC1' unequal to 'YCN', then YOTP will lie in the
104                          range from 'YC1' (corresponding to an index value of
105                          1) to 'YCN' (corresponding to an index value of N).
106
107                          In any case, if the point (XINP,YINP) cannot be
108                          mapped for any reason, some recognizable impossible
109                          value should be returned for both of XOTP and YOTP
110                          and the internal parameter 'ORV' should be given
111                          that value, thereby allowing Conpack routines that
112                          call CPMPXY to determine whether or not a point
113                          being projected is visible or not.  The value used
114                          for this purpose by the Ezmap routines MAPTRA and
115                          MAPTRI is 1.E12.
116

USAGE

118       CPMPXY is not to be called by the user. It is called by Conpack when
119       the parameter 'MAP' is non-zero. Each call is intended 1) to inquire
120       whether a given mapping is defined by CPMPXY, or 2) to map the X and Y
121       coordinates of a single point, whose position is known relative to the
122       data grid, to X and Y coordinates in some other coordinate system or 3)
123       (as of version 3.1.3) to do the inverse mapping. The default version of
124       CPMPXY is as follows:
125
126            SUBROUTINE CPMPXY (IMAP,XINP,YINP,XOTP,YOTP)
127              IF (IMAP.EQ.0) THEN
128                IF (INT(XINP).GE.1.AND.INT(XINP).LE.3) THEN
129                  YINP=3.
130                ELSE
131                  YINP=0.
132                END IF
133              ELSE IF (ABS(IMAP).EQ.1) THEN
134                IF (IMAP.GT.0) THEN
135                  CALL MAPTRA (YINP,XINP,XOTP,YOTP)
136                ELSE
137                  CALL MAPTRI (XINP,YINP,YOTP,XOTP)
138                END IF
139              ELSE IF (ABS(IMAP).EQ.2) THEN
140                IF (IMAP.GT.0) THEN
141                  XOTP=XINP*COS(.017453292519943*YINP)
142                  YOTP=XINP*SIN(.017453292519943*YINP)
143                ELSE
144                  XOTP=SQRT(XINP*XINP+YINP*YINP)
145                  YOTP=57.2957795130823*ATAN2(YINP,XINP)
146                END IF
147              ELSE
148                XOTP=XINP
149                YOTP=YINP
150              END IF
151              RETURN
152            END
153
154       When CPMPXY is called with IMAP = 0, it assumes it is being
155       asked to return information about its mapping capabilities.
156       XINP is assumed to have been given the value REAL(I), where
157       I is the index of a mapping about which information is
158       desired. CPMPXY sets YINP to indicate whether the mapping
159       selected by I is implemented or not and whether its inverse
160       is implemented or not. In the case of the default version
161       of CPMPXY, mappings 1 through 3 are completely implemented
162       (both forward and reverse), so a "3." is returned as the
163       value of YINP; other mappings are not implemented at all,
164       so a "0." is returned as the value of YINP.
165
166       When CPMPXY is called with IMAP = 1, the incoming X and Y
167       coordinates are assumed to represent longitude and
168       latitude, respectively; the Ezmap routine MAPTRA is called
169       to find the X and Y coordinates of the projection of the
170       specified point on the globe, and those coordinates are
171       returned as the outgoing X and Y coordinates. When IMAP =
172       -1, the incoming X and Y coordinates are assumed to be the X
173       and Y coordinates of a projected point; the Ezmap routine
174       MAPTRI is called to find the longitude and latitude of the
175       original point on the globe, and those values are returned
176       as the outgoing X and Y coordinates.
177
178       When IMAP = 2, the incoming X and Y coordinates are assumed
179       to represent rho and theta (in degrees) in polar
180       coordinates; from these are computed the output X and Y
181       coordinates. When IMAP = -2, the incoming X and Y
182       coordinates are used to compute rho and theta and those
183       values are returned.
184
185       If IMAP is anything else, the input X and Y coordinates are
186       simply returned as the output X and Y coordinates.
187
188       A user version of CPMPXY can be made to do any desired
189       mapping. It should also be made, when IMAP = 0, to return
190       correct information about its own capabilities.
191

ACCESS

193       To use CPMPXY, load the NCAR Graphics libraries ncarg, ncarg_gks, and
194       ncarg_c, preferably in that order.
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SEE ALSO

197       Online: conpack, cpback, cpchcf, cpchcl, cpchhl, cpchil, cpchll,
198       cpcica, cpclam, cpcldm, cpcldr, cpcltr, cpcnrc, cpdrpl, cpezct, cpgetc,
199       cpgeti, cpgetr, cplbam, cplbdr, cpmviw, cpmvrw, cppkcl, cppklb, cprect,
200       cprset, cpscae, cpsetc, cpseti, cpsetr, cpsps1, cpsps2, ncarg_cbind
201
202       Hardcopy: NCAR Graphics Contouring and Mapping Tutorial
203
205       Copyright (C) 1987-2009
206       University Corporation for Atmospheric Research
207
208       The use of this Software is governed by a License Agreement.
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212UNIX                              March 1993                    CPMPXY(3NCARG)
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