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

6       STREAM - Plots a streamline representation of field flow data, based on
7       conditions established by STINIT and the current values of a set of
8       user-modifiable internal parameters associated with the Streamlines
9       utility.
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SYNOPSIS

12       CALL STREAM (U,V,P,IAM,STUMSL,WRK)
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C-BINDING SYNOPSIS

15       #include <ncarg/ncargC.h>
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17       void c_stream(float *u, float *v, float *p, int *iam,
18                     int (*stumsl_)( float *xcs, float *ycs,
19                     int *ncs, int *iai, int *iag, int *nai),
20                     float *wrk)
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DESCRIPTION

23       U           (REAL 2 dimensional array, dimensioned as specified in last
24                   call to STINIT, input): By default, assumed to contain the
25                   first dimensional axis components of the vector field.
26                   However, if PLR is non-zero, it is treated as containing
27                   the vector magnitudes.
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29       V           (REAL 2 dimensional array, dimensioned as specified in last
30                   call to STINIT, input): By default, assumed to contain the
31                   second dimensional axis components of the vector field.
32                   However, if PLR is non-zero, it is treated as containing
33                   the vector angles.
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35       P           (REAL, input, DUMMY): This argument is currently ignored.
36                   May be assigned a dummy value.
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38       IAM         (INTEGER array, unknown dimension, input): Area map array
39                   previously established by calls to routines in the Areas
40                   utility. It is checked to see that the number of area
41                   groups is within the limits allowed by Streamlines, then
42                   simply passed through to an Areas routine for further
43                   processing. Required only if MSK is set to a non-zero
44                   value; otherwise it is ignored and may be assigned a dummy
45                   value.
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47       STUMSL      (EXTERNAL subroutine, input): User-definable masked drawing
48                   subroutine.  Required only if MSK is set to a non-zero
49                   value; otherwise it is ignored and may be assigned a dummy
50                   value.
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52       WRK         (REAL array, dimensioned as specified in last call to
53                   STINIT, input/output): Work array used to store normalized
54                   values of the U and V vector components while the
55                   streamlines are calculated. It also holds bit flags
56                   indicating whether a grid location is eligible for starting
57                   a streamline or placing a directional arrowhead.
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C-BINDING DESCRIPTION

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

64       A call to STINIT must precede the first call to STREAM, and is again
65       required any time the vector array data changes or any of the
66       coordinate space control parameters are modified. However, you may
67       modify certain rendering control parameters between multiple
68       invocations of STREAM. See the streamlines_params man page for more
69       information.
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71       Arguments to STINIT establish the sizes of the vector component arrays
72       and the WRK array. STINIT places these values into common block
73       variables where they become available to STREAM.  Therefore no size
74       arguments need appear in the STREAM argument list.  When area masking
75       is not enabled, the third, fourth and fifth arguments to STREAM may all
76       have dummy values and the invocation would be something like:
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78               CALL STREAM(U,V,IDM,IDM,IDM,WRK)
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80       where IDM is an arbitrary variable that need not have been initialized.
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82       The masking capability supported by Streamlines allows you to overlay
83       streamlines on graphics produced by other utilities, such as Conpack
84       contour plots, without encroaching on areas, like label boxes, that
85       should appear in the foreground. Normally the area map should be
86       generated and used in the normal way (as described in the Areas and
87       Conpack documentation) before calling any routines in the Streamlines
88       utility. When the parameter MSK has a non-zero value, masking is
89       enabled and a previously created area map must be passed to STREAM.
90       STREAM examines the map, returning an error if the map appears to be
91       invalid or the number of area groups is beyond the range it can handle
92       (currently 64). Otherwise, it only uses the map as an argument to the
93       Areas utility subroutine, ARDRLN. The user must also pass in a user-
94       definable masked drawing subroutine. A simple version of this
95       subroutine, named (like the argument) STUMSL, is supplied with the
96       Streamlines utility, and may suffice for basic masked drawing
97       operations. See the stumsl man page for more information.
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99       The P array argument is intended for future enhancement of the
100       Streamlines utility and is not currently used or examined in any way.
101       You may pass it an uninitialized dummy argument.
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EXAMPLES

104       Use the ncargex command to see the following relevant examples: ffex00,
105       ffex01, ffex03, ffex04, fstream, stex01, stex02, stex03, stex03.
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ACCESS

108       To use STREAM or c_stream, load the NCAR Graphics libraries ncarg,
109       ncarg_gks, and ncarg_c, preferably in that order.
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MESSAGES

112       See the streamlines man page for a description of all Streamlines error
113       messages and/or informational messages.
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SEE ALSO

116       Online: stgetc, stgeti, stgetr, stinit, streamlines,
117       streamlines_params, strset, stsetc, stseti, stsetr, stuixy, stumsl,
118       stumta, stumxy, ncarg_cbind.
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120       Hardcopy: NCAR Graphics Fundamentals, UNIX Version
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123       Copyright (C) 1987-2009
124       University Corporation for Atmospheric Research
125       The use of this Software is governed by a License Agreement.
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129UNIX                              April 1993                    STREAM(3NCARG)
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