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

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       STRMLN is obsolete, and is supported only to provide compatibility with old NCAR Graphics codes.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.

UNIX                                               April 1993                                     STRMLN(3NCARG)