1Vectors(3NCARG) NCAR GRAPHICS Vectors(3NCARG)
2
6 Vectors - Utility for creating a vector field plot given two arrays
7 containing the vector components on a uniform grid. In addition, the
8 user may pass in another array of scalar data defined over the same
9 grid space independent of but presumably related in some fashion to the
10 vector data. The utility will then color each vector based on the
11 scalar value at the grid point. Alternatively, the user can choose to
12 color the vectors based on vector magnitude.
13
15 The following two calls are the minimum required to create a vector
16 field plot using the current interface:
17 · VVINIT - Performs the initialization required for VVECTR to
19 interpret the input array data properly. VVINIT stores the data
20 array sizes, sets up various coordinate system mappings, and
21 processes the input arrays to find the maximum and minimum
22 values. If vector coloring is enabled and the user has not
23 explicitly taken control, the routine establishes a linearly
24 scaled color threshold array.
25 · VVECTR - Renders the vectors based on conditions established by
27 VVINIT and the current values of a set of user-modifiable
28 internal parameters associated with the Vectors utility.
29 All user-modifiable internal parameters have default values; only those
31 which are to have values different from the default need to be set. The
32 routines used to set Vectors parameters are as follows:
33 · VVRSET - Resets all internal parameters to their default values.
35 · VVSETC - Assigns a value of type CHARACTER to a parameter.
37 · VVSETI - Assigns a value of type INTEGER to a parameter.
39 · VVSETR - Assigns a value of type REAL to a parameter.
41 In general, once a parameter is given a value by a call to one of these
43 routines, it retains that value until a similar call resets it.
44 Retrieve the value of an internal parameter by calling one of the
45 following routines:
46 · VVGETC - Returns a parameter value of type CHARACTER.
48 · VVGETI - Returns a parameter value of type INTEGER.
50 · VVGETR - Returns a parameter value of type REAL.
52 ·
54 Vectors supports three obsolete routines for compatibility with old
56 NCAR Graphics codes. The compatibility mode parameter, CPM, offers a
57 number of options that allow considerable flexibility in making the
58 transition to the new version of the utility. When writing new code you
59 are encouraged not to use these entry points, since they provide less
60 capability than the standard Vectors interface, and may eventually be
61 phased out.
62 · VELVCT - The principal entry point prior to Version 3.2, now a
64 front end to the VVINIT/VVECTR interface.
65 · EZVEC - Front end to VELVCT: a simpler interface for standard
67 situations, when detailed control of the plot is not required.
68 · VELVEC - Older version of VELVCT and now also a front end to it.
70 It differs from the VELVCT call only in that it contains one
71 less input argument in its calling sequence.
72
74 c_vvinit
75 c_vvectr
76 c_vvrset
77 c_vvsetc
78 c_vvseti
79 c_vvsetr
80 c_vvgetc
81 c_vvgeti
82 c_vvgetr
83 c_velvct
84 c_ezvec
85 c_velvec
86
88 The following routines are not to be called directly. However, you may
89 modify them in order to customize the behavior of Vectors. VVUMXY is
90 provided to support user-defined mapping transformations. VVUDMV allows
91 you to tailor vector masking to your requirements.
92 · VVUMXY - Performs a user-definable mapping of vector position
94 and direction from data coordinate space to normalized device
95 coordinate space.
96 · VVUDMV - The default name of a routine used to draw vectors
98 masked to an area map. VVUDMV decides which segments of a vector
99 to draw depending on the area group and group identifier arrays
100 passed to it.
101
103 To use Vectors, load the NCAR Graphics libraries ncarg, ncarg_gks, and
104 ncarg_c, preferably in that order.
105
107 In this section are listed, in alphabetical order, all the error
108 messages that may be written by Vectors. Each error message begins with
109 the name of the Vectors routine in which an error has been detected,
110 followed by a dash, followed by the error message itself. These error
111 messages are written by a call to the error-handling support routine
112 SETER, with a final argument indicating that the error is fatal and
113 that execution should be terminated.
114 VVECTR - TOO MANY AREA GROUPS
116 The area map passed as the argument, IAM, to VVECTR contains
117 more area groups than allowed by the Vectors utility, currently
118 64. This error can occur only if the Mask to Area Map parameter,
119 MSK, has a value greater than 0, specifying that vectors are to
120 be drawn masked to an area map.
121 VVECTR - INVALID AREA MAP
123 The area map passed as the argument, IAM, to VVECTR is judged to
124 be invalid because it contains a negative value for the number
125 of area groups. This error can occur only if the Mask to Area
126 Map parameter, MSK, has a value greater than 0, specifying that
127 vectors are to be drawn masked to an area map.
128 VVGETC - PARAMETER NAME NOT KNOWN - x
130 The given parameter name (´x´) is not a legal parameter name
131 known to Vectors.
132 VVGETC - PARAMETER NAME TOO SHORT - x
134 The parameter name ("x") is less than three characters long.
135 VVGETI OR VVGETR - GETTING x - PAI INCORRECT
137 An attempt has been made to get an element of the parameter
138 array named ´x´ and the current value of PAI (the "parameter
139 array index") is inappropriate for that parameter array.
140 VVGETI OR VVGETR - PARAMETER NAME NOT KNOWN - x
142 The given parameter name (´x´) is not a legal parameter name
143 known to Vectors.
144 VVGETI OR VVGETR - PARAMETER NAME TOO SHORT - x
146 The parameter name ("x") is less than three characters long.
147 VVINIT - U AND/OR V ARRAY DIMENSIONS EXCEEDED
149 The VVINIT input argument, M, specifying the number of array
150 elements to use along the first dimension of the U and V (and
151 possibly P) arrays, exceeds the actual first dimension of U
152 and/or V, as specified by the input arguments LU and LV.
153 VVINIT - SCALAR ARRAY TOO SMALL
155 The value given to LP, the VVINIT input argument specifying the
156 actual first dimension of the scalar data array, P, is less than
157 M, the input argument specifying the number of array elements to
158 use along the first dimension for all of the input arrays. This
159 error can only occur when the absolute value of the Color
160 Threshold Level control parameter, CTV, is set to 2, indicating
161 that coloring is to be performed according to values contained
162 in the scalar data array, P.
163 VVSETC - PARAMETER NAME NOT KNOWN - x
165 The given parameter name (´x´) is not a legal parameter name
166 known to Vectors.
167 VVSETC - PARAMETER NAME TOO SHORT - x
169 The parameter name ("x") is less than three characters long.
170 VVSETI OR VVSETR - PARAMETER NAME NOT KNOWN - x
172 The given parameter name (´x´) is not a legal parameter name
173 known to Vectors.
174 VVSETI OR VVSETR - PARAMETER NAME TOO SHORT - x
176 The parameter name ("x") is less than three characters long.
177 VVSETI OR VVSETR - PARAMETER VALUE OUT OF RANGE - x
179 An attempt has been made to set the parameter named ´x´ to a
180 value outside the range allowed by the Vectors utility.
181 VVSETI OR VVSETR - SETTING x - PAI INCORRECT
183 An attempt has been made to set an element of the parameter
184 array named ´x´ and the current value of PAI (the "parameter
185 array index") is inappropriate for that parameter array.
186
188 Online: vectors_params, ezvec, velvec, velvct, fx, fy, vvectr, vvgetc,
189 vvgeti, vvgetr, vvinit, vvrset, vvsetc, vvseti, vvsetr, vvudmv, vvumxy,
190 ncarg_cbind.
191 Hardcopy: NCAR Graphics Fundamentals, UNIX Version
193
195 Copyright (C) 1987-2007
196 University Corporation for Atmospheric Research
197 This documentation is free software; you can redistribute it and/or
199 modify it under the terms of the GNU General Public License as
200 published by the Free Software Foundation; either version 2 of the
201 License, or (at your option) any later version.
202 This software is distributed in the hope that it will be useful, but
204 WITHOUT ANY WARRANTY; without even the implied warranty of
205 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
206 General Public License for more details.
207 You should have received a copy of the GNU General Public License along
209 with this software; if not, write to the Free Software Foundation,
210 Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
211UNIX April 1993 Vectors(3NCARG)