1Streamlines(3NCARG) NCAR GRAPHICS Streamlines(3NCARG)
2
6 Streamlines - Utility for plotting a streamline representation of field
7 flow data given two arrays containing the vector field components on a
8 uniform grid.
9
11 The following two calls are the minimum required to create a streamline
12 field flow plot using the current interface:
13 · STINIT - Performs initialization tasks required before STREAM
15 may be called to create a streamline field flow plot.
16 Information about the input data arrays is copied into internal
17 common block variables and the coordinate system mappings and
18 boundaries are established.
19 · STREAM - Plots a streamline representation of field flow data,
21 based on conditions established by STINIT and the current values
22 of a set of user-modifiable internal parameters associated with
23 the Streamlines utility.
24 All user-modifiable internal parameters have default values; only those
26 which are to have values different from the default need to be set. The
27 routines used to set Streamlines parameters are as follows:
28 · STRSET - Resets all parameters to their initial default values.
30 · STSETI - Sets the value of an internal parameter of type
32 INTEGER.
33 · STSETR - Sets the value of an internal parameter of type REAL.
35 In general, once a parameter is given a value by a call to one of these
37 routines, it retains that value until a similar call resets it.
38 Retrieve the value of an internal parameter by calling one of the
39 following routines:
40 · STGETI - Gets the current value of an internal parameter of type
42 INTEGER.
43 · STGETR - Gets the current value of an internal parameter of type
45 REAL.
46 Streamlines supports two obsolete routines for compatibility with old
48 NCAR Graphics codes. The compatibility mode parameter, CPM, offers a
49 number of options that allow considerable flexibility in making the
50 transition to the new version of the utility. When writing new code you
51 are encouraged not to use these entry points, since they provide less
52 capability than the standard Streamlines interface, and may eventually
53 be phased out.
54 · STRMLN - The principal entry point prior to Version 3.2, now a
56 front end to the STINIT/STREAM interface.
57 · EZSTRM - Front end to STRMLN: a simpler interface for standard
59 situations, when detailed control of the plot is not required.
60
62 c_stinit
63 c_stream
64 c_strset
65 c_stseti
66 c_stsetr
67 c_stgeti
68 c_stgetr
69 c_strmln
70 c_ezstrm
71
73 The following routines are not to be called directly. However, you may
74 modify them in order to customize the behavior of Streamlines. Three
75 routines (STUMXY, STUIXY, and STUMTA) are provided to support user-
76 defined mapping transformations. The fourth (STUMSL) allows you to
77 tailor streamline masking to your requirements.
78 · STUIXY - User modifiable routine that inversely maps a single
80 point on the streamline from user to data coordinate space.
81 · STUMSL - Default name for a user-definable external subroutine
83 used to draw masked streamlines. The default version of the
84 routine draws any polyline all of whose area identifiers are
85 greater than or equal to zero.
86 · STUMTA - Given the coordinates of a point on the streamline in
88 data, user, and NDC space, and the interpolated, normalized
89 components of the vector at the point relative to data
90 coordinate space, the user-modifiable routine STUMTA finds the
91 directional angle of the streamline relative to NDC space at the
92 point.
93 · STUMXY - User modifiable routine that maps a single point on the
95 streamline from data to user coordinate space.
96
98 To use Streamlines, load the NCAR Graphics libraries ncarg, ncarg_gks,
99 and ncarg_c, preferably in that order.
100
102 In this section are listed, in alphabetical order, all the error
103 messages that may be written by Streamlines. Each error message begins
104 with the name of the Streamlines routine in which an error has been
105 detected, followed by a dash, followed by the error message itself.
106 These error messages are written by a call to the error-handling
107 support routine SETER, with a final argument indicating that the error
108 is fatal and that execution should be terminated.
109 STGETI OR STGETR - PARAMETER NAME NOT KNOWN - x
111 The given parameter name (´x´) is not a legal parameter name
112 known to Streamlines.
113 STGETI OR STGETR - PARAMETER NAME TOO SHORT - x
115 The parameter name ("x") is less than three characters long.
116 STINIT - U AND/OR V ARRAY DIMENSIONS EXCEEDED
118 The STINIT input argument, M, specifying the number of array
119 elements to use along the first dimension of the U and V arrays,
120 exceeds the actual first dimension of U and/or V, as specified
121 by the input arguments LU and LV.
122 STREAM - TOO MANY AREA GROUPS
124 The area map passed as the argument, IAM, to STREAM contains
125 more area groups than allowed by the Streamlines utility,
126 currently 64. This error can occur only if the mask to area map
127 parameter, MSK, has a value greater than 0, specifying that
128 streamlines are to be drawn masked to an area map.
129 STREAM - INVALID AREA MAP
131 The area map passed as the argument, IAM, to STREAM is judged to
132 be invalid because it contains a negative value for the number
133 of area groups. This error can occur only if the mask to area
134 map parameter, MSK, has a value greater than 0, specifying that
135 streamlines are to be drawn masked to an area map.
136 STSETI OR STSETR - PARAMETER NAME NOT KNOWN - x
138 The given parameter name (´x´) is not a legal parameter name
139 known to Streamlines.
140 STSETI OR STSETR - PARAMETER NAME TOO SHORT - x
142 The parameter name ("x") is less than three characters long.
143 STSETI OR STSETR - PARAMETER VALUE OUT OF RANGE - x
145 An attempt has been made to set the parameter named ´x´ to a
146 value outside the range allowed by the Streamlines utility.
147
149 Online: stgetc, stgeti, stgetr, stinit, stream, streamlines_params,
150 strset, stsetc, stseti, stsetr, stuixy, stumsl, stumta, stumxy,
151 ncarg_cbind.
152 Hardcopy: NCAR Graphics Fundamentals, UNIX Version
154
156 Copyright (C) 1987-2009
157 University Corporation for Atmospheric Research
158 The use of this Software is governed by a License Agreement.
159UNIX April 1993 Streamlines(3NCARG)