NAME¶
Streamlines - Utility for plotting a streamline representation of field flow
data given two arrays containing the vector field components on a uniform
grid.
SYNOPSIS¶
The following two calls are the minimum required to create a streamline field
flow plot using the current interface:
- •
- STINIT - Performs initialization tasks required before STREAM may be
called to create a streamline field flow plot. Information about the input
data arrays is copied into internal common block variables and the
coordinate system mappings and boundaries are established.
- •
- STREAM - Plots a streamline representation of field flow data, based on
conditions established by STINIT and the current values of a set of
user-modifiable internal parameters associated with the Streamlines
utility.
All user-modifiable internal parameters have default values; only those which
are to have values different from the default need to be set. The routines
used to set Streamlines parameters are as follows:
- •
- STRSET - Resets all parameters to their initial default values.
- •
- STSETI - Sets the value of an internal parameter of type INTEGER.
- •
- STSETR - Sets the value of an internal parameter of type REAL.
In general, once a parameter is given a value by a call to one of these
routines, it retains that value until a similar call resets it. Retrieve the
value of an internal parameter by calling one of the following routines:
- •
- STGETI - Gets the current value of an internal parameter of type
INTEGER.
- •
- STGETR - Gets the current value of an internal parameter of type
REAL.
Streamlines supports two obsolete routines for compatibility with old NCAR
Graphics codes. The compatibility mode parameter, CPM, offers a number of
options that allow considerable flexibility in making the transition to the
new version of the utility. When writing new code you are encouraged not to
use these entry points, since they provide less capability than the standard
Streamlines interface, and may eventually be phased out.
- •
- STRMLN - The principal entry point prior to Version 3.2, now a front end
to the STINIT/STREAM interface.
- •
- EZSTRM - Front end to STRMLN: a simpler interface for standard situations,
when detailed control of the plot is not required.
C-BINDING SYNOPSIS¶
c_stinit
c_stream
c_strset
c_stseti
c_stsetr
c_stgeti
c_stgetr
c_strmln
c_ezstrm
USER-MODIFIABLE INTERNAL ROUTINES¶
The following routines are not to be called directly. However, you may modify
them in order to customize the behavior of Streamlines. Three routines
(STUMXY, STUIXY, and STUMTA) are provided to support user-defined mapping
transformations. The fourth (STUMSL) allows you to tailor streamline masking
to your requirements.
- •
- STUIXY - User modifiable routine that inversely maps a single point on the
streamline from user to data coordinate space.
- •
- STUMSL - Default name for a user-definable external subroutine used to
draw masked streamlines. The default version of the routine draws any
polyline all of whose area identifiers are greater than or equal to
zero.
- •
- STUMTA - Given the coordinates of a point on the streamline in data, user,
and NDC space, and the interpolated, normalized components of the vector
at the point relative to data coordinate space, the user-modifiable
routine STUMTA finds the directional angle of the streamline relative to
NDC space at the point.
- •
- STUMXY - User modifiable routine that maps a single point on the
streamline from data to user coordinate space.
ACCESS¶
To use Streamlines, load the NCAR Graphics libraries ncarg, ncarg_gks, and
ncarg_c, preferably in that order.
MESSAGES¶
In this section are listed, in alphabetical order, all the error messages that
may be written by Streamlines. Each error message begins with the name of the
Streamlines routine in which an error has been detected, followed by a dash,
followed by the error message itself. These error messages are written by a
call to the error-handling support routine SETER, with a final argument
indicating that the error is fatal and that execution should be terminated.
- STGETI OR STGETR - PARAMETER NAME NOT KNOWN - x
- The given parameter name (´x´) is not a legal parameter name
known to Streamlines.
- STGETI OR STGETR - PARAMETER NAME TOO SHORT - x
- The parameter name ("x") is less than three characters
long.
- STINIT - U AND/OR V ARRAY DIMENSIONS EXCEEDED
- The STINIT input argument, M, specifying the number of array elements to
use along the first dimension of the U and V arrays, exceeds the actual
first dimension of U and/or V, as specified by the input arguments LU and
LV.
- STREAM - TOO MANY AREA GROUPS
- The area map passed as the argument, IAM, to STREAM contains more area
groups than allowed by the Streamlines utility, currently 64. This error
can occur only if the mask to area map parameter, MSK, has a value greater
than 0, specifying that streamlines are to be drawn masked to an area
map.
- STREAM - INVALID AREA MAP
- The area map passed as the argument, IAM, to STREAM is judged to be
invalid because it contains a negative value for the number of area
groups. This error can occur only if the mask to area map parameter, MSK,
has a value greater than 0, specifying that streamlines are to be drawn
masked to an area map.
- STSETI OR STSETR - PARAMETER NAME NOT KNOWN - x
- The given parameter name (´x´) is not a legal parameter name
known to Streamlines.
- STSETI OR STSETR - PARAMETER NAME TOO SHORT - x
- The parameter name ("x") is less than three characters
long.
- STSETI OR STSETR - PARAMETER VALUE OUT OF RANGE - x
- An attempt has been made to set the parameter named ´x´ to a
value outside the range allowed by the Streamlines utility.
SEE ALSO¶
Online: stgetc, stgeti, stgetr, stinit, stream, streamlines_params, strset,
stsetc, stseti, stsetr, stuixy, stumsl, stumta, stumxy, 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.