Ubuntu Manpage: STRMLN - Plots a streamline representation of field flow data, given two 2-dimensional

Provided by: libncarg-dev_6.6.2.dfsg.1-4_amd64

NAME

       STRMLN - Plots a streamline representation of field flow data, given two 2-dimensional
       vector component arrays, U and V. You may control certain characteristics of the plot by
       adjusting the values given to the input arguments. In addition, depending on the value
       given to the compatibility parameter, CPM, you may set other options by calling STSETI or
       STSETR to modify internal parameters.

STATUS

       STRMLN is obsolete, and is supported only to provide compatibility with old NCAR Graphics
       codes. However, the compatibility mode parameter, CPM, offers a number of options to help
       ease the the transition to the new version of the utility. When writing new code you are
       encouraged not to use this entry point, since it provides less capability than the
       standard Streamlines interface, and may eventually be phased out.

SYNOPSIS

       CALL STRMLN (U,V,WORK,IMAX,IPTSX,JPTSY,NSET,IER)

C-BINDING SYNOPSIS

       #include <ncarg/ncargC.h>

       void c_strmln (float *u, float *v, float *work, int imax,
                      int iptsx, int jptsy, int nset, int *ier)

DESCRIPTION

U (REAL 2-dimensional array, dimensioned IMAX x n: n >= JPTSY, input): By
default, assumed to contain the first dimensional Cartesian components of the
vector field. However, if PLR is non-zero, it is treated as containing the
vector magnitudes.

V (REAL 2-dimensional array, dimensioned IMAX x n: n >= JPTSY, input): By
default, assumed to contain the second dimensional Cartesian components of the
vector field. However, if PLR is non-zero, it is treated as containing the
vector angles.

WORK (REAL array, dimensioned n: n>= 2*IPTSX*JPTSY, working space): User provided
work array used to store the normalized vector component values, and also to
keep track of the grid boxes eligible for starting a streamline or placement
of a directional arrow.

IMAX (INTEGER, input): Actual value of the first dimension of arrays U and V.

IPTSX (INTEGER, input): Number of contiguous elements along the first dimensional
axis containing data to be processed in each of the arrays, U and V.

JPTSY (INTEGER, input): Number of contiguous elements along the second dimensional
axis containing data to be processed in each of the arrays, U and V.

NSET (INTEGER, input) Flag that controls how and when the SET call is invoked. If
NSET is 0, STRMLN makes a SET call to establish a standard viewport and window
boundaries coincident with the array coordinate boundaries. PERIM is called to
draw a border. If NSET is greater than zero, STRMLN does not call SET or
PERIM. If NSET is less than zero, STRMLN calls SET to establish window
boundaries coincident with the array grid coordinate boundaries but does not
modify the viewport or call PERIM. Unlike the STINIT/STREAM interface, when
STRMLN does a SET call, it always restores the original coordinate system
state before returning.

IER (INTEGER, output) If no error involving the ICYC common block variable (or,
depending on the compatibility mode, the CYK internal parameter) is detected
IER contains the value 0 on exit from STRMLN. If, when STRMLN is invoked, ICYC
(or CYK) is erroneously set to indicate that the data is cyclic, STRMLN still
processes the data using non-cyclic interpolation formulas, but returns the
value of -1 in IER.

C-BINDING DESCRIPTION

       The C-binding argument descriptions are the same as the FORTRAN argument descriptions,
       with the following exceptions:

       imax        The second dimension of u and v in the calling program

       iptsx       Number of contiguous elements along the second dimensional axis containing
                   data to be processed in each of the arrays, u and v.

       jptsy       Number of contiguous elements along the first dimensional axis containing data
                   to be processed in each of the arrays, u and v.

USAGE

       Beginning with version 3.2 of NCAR Graphics, the STRMLN entry point has been recoded as a
       front end to the STINIT/STREAM interface to Streamlines. The compatibility mode parameter,
       CPM, controls the degree to which a call to the Version 3.2 STRMLN emulates the older
       call. Appropriate settings of CPM can separately answer each of the following three
       questions regarding the level of emulation:

       •      Should FX and FY rather than the Version 3.2 mapping routines perform the mapping
              to user coordinates?

       •      Should the value of the input argument, NSET, override the current value of the SET
              parameter?

       •      Should the values contained in the common blocks STR02 and STR03 override the
              current values of corresponding Streamlines' internal parameters?

       Given the default value of CPM, all these questions are answered in the affirmative, and a
       call to STRMLN gives a reasonably faithful emulation of the older version's behavior.

       However, even in this case, it is possible to use the parameter setting routines to
       control the behavior of features that have no counterpart in the older version of STRMLN,
       as long as the feature is accessible without calling the new interface. For instance, you
       could control the streamline linewidth by setting the LWD parameter, but on the other hand
       you could not draw streamlines masked to an area map because doing so requires direct
       invocation of STREAM with the proper input arguments. The following two tables show how
       the STRMLN input arguments and STR02/STR03 common block members map into internal
       parameters currently supported by Streamlines:

              Input Argument        Internal Parameter

              NSET                  SET (NSET = 0 is approximately equivalent to SET = 1)

              Common Block Member   Internal Parameter

              INITA                 SGD

              INITB                 AGD

              ITERP                 CKP

              ITERC                 CKX

              IGFLG                 TRP

              ICYC                  CYK

              IMSG                  SVF

              UVMSG                 USV

              UVMSG                 VSV

              DISPL                 VNL

              AROWL                 ARL (AROWL as fraction of grid box size is converted to ARL
                                    as fraction of viewport width)

              CSTOP                 SSP (CSTOP as fraction of grid box size is converted to SSP
                                    as fraction of viewport width)

              DISPL                 DFM (DISPL as fraction of grid box size is converted to DFM
                                    as fraction of viewport width)

              DISPC/DISPL           CDS (The critical displacement multiplier CDS is calculated
                                    as the ratio of DISPC to DISPL)

       See the streamlines_params man page for a description of the internal parameters.

EXAMPLES

       Use the ncargex command to see the following relevant examples: stex02, tstrml.

ACCESS

       To use STRMLN or c_strmln, load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c,
       preferably in that order.

COPYRIGHT

       Copyright (C) 1987-2009
       University Corporation for Atmospheric Research
       The use of this Software is governed by a License Agreement.