Streamlines_params - This document briefly describes all
Streamlines internal parameters.
Parameter descriptions follow, in alphabetical order. Each
description begins with a line giving the three-character mnemonic name of
the parameter, the phrase for which the mnemonic stands, and the intrinsic
type of the parameter.
- AGD - Arrow Placement Grid
Increment - Integer
- This parameter allows you a degree of control over directional arrowhead
spacing in the field flow plot. Streamlines allows a maximum of one
directional arrowhead for each grid box, where a grid box is the space
between adjacent integer grid coordinates in the grid coordinate system
along both dimensions. However, Streamlines actually places an arrowhead
only if both lower grid indices, modulo the value of AGD, are equal to 0.
If AGD is set to 2, for instance, Streamlines places an arrowhead on the
first streamline to enter each grid box with even-numbered lower grid
indices.
If the transformation pipeline is everywhere linear from grid
coordinate space to NDC space, then the spacing of the arrowheads should
be more or less uniform over the field flow plot. However, if there is a
non-linearity anywhere in the pipeline, the arrowheads will probably be
more crowded in some areas than in others. The default value of AGD is
2.
- AMD - Arrow Head Minimum
Distance - Real
- AMD allows you to specify, as a fraction of the viewport width, a minimum
distance between adjacent directional arrowheads along a single
streamline. If the data grid is transformed in such a way that adjacent
grid cells become very close in NDC space, as for instance in many map
projections near the poles, you can use this parameter to help reduce the
otherwise cluttered appearance of these regions of the plot. Note that
currently, whenever AMD has a positive value, the first arrowhead that
would otherwise be drawn for each streamline is always eliminated. If AMD
is less than or equal to 0.0, then no arrowheads are eliminated. The
default value of AMD is 0.0.
- ARL - Arrow Head Length -
Real
- ARL defines the length of each of the two lines used to create the
directional arrow head. If the parameter GBS is set to 0, ARL has units
"fraction of viewport width"; if GBS is set to 1, ARL has the
units "fraction of grid box width". The default value of ARL is
0.012 when GBS has the value 0 and 0.33 when GBS has the value 1. Setting
GBS causes ARL to be reset to its appropriate default value.
- CDS - Critical Displacement
Multiplier - Real
- CDS specifies the minimum amount the streamline must grow as a multiple of
the basic differential step size each time the stream progress is checked
in order for the streamline not to be terminated. The nominal differential
step size is specified by DFM in NDC space, and the progress is checked
each CKP iterations. Points of convergence or divergence typically cause
stream growth to diminish and the streamline eventually to be terminated.
The default value of CDS is 2.0, meaning that any time a streamline does
not increase in length a minimum of 2.0*DFM in NDC over the previous
check, it is discontinued and a new streamline is begun if possible.
- CKP - Check Progress Iteration
Count - Integer
- The parameter CKP specifies the number of iterations through the
streamline building loop between each check of the streamline growth. If
the distance between current position of the streamline and the position
saved at the time of the previous check is less than a minimum amount,
defined as the value of CDS times the value of DFM in NDC space, then the
current streamline is terminated and a new one begun if possible. The
default value of CKP is 35.
- CKX - Check Crossover Iteration
Count - Integer
- CKX specifies the number of iterations through the streamline building
loop between checks for streamline crossover, that is, one streamline
growing closer than a certain distance (as specified by the parameter SSP)
to previously created streamline. A negative value of CKX causes
Streamlines to check for crossover only when a new grid box is entered. At
each crossover check, the current streamline position is compared with a
sampling of previous streamline positions retained in an internal circular
list. This list is currently fixed to a length of 750. Since up to this
number of comparisons are performed at each crossover check, the frequency
with which these checks are performed can have a noticeable impact on
performance. By default, CKX has the value -99, causing Streamlines to
check for crossover only on entrance to a new grid box.
- CYK - Cyclical Data Flag -
Integer
- Use this parameter to specify that the data in the vector field arrays is
cyclical: that is, it repeats with a period of M-1 (M, the input parameter
to STINIT) along the first dimensional axis. If the flag is set on,
Streamlines checks to see if the field data meet certain criteria. If they
do, an internal cyclical flag is set, causing the normalized vector
interpolation routines to consider data from the opposite ends of the
dataset when interpolating near the first dimensional dataset boundaries.
If the criteria are not met, Streamlines sets an error flag, retrievable
by the user through the parameter ERR. Processing, however, continues
without interruption, except that Streamlines now interpolates (as it
would ordinarily) near the first dimensional end points without
consideration of data at the opposite end. The data must pass the
following test in order to be deemed cyclical: for each subscript value
along the second dimensional axis, the first element and the last element
along the first dimensional axis must be identical. A value of 0 for CYK
means that the data is to be considered non-cyclical; any other value
means that Streamlines should test for the cyclical condition. You must
initialize Streamlines with a call to STINIT after modifying this
parameter. The default value of CYK is 0.
- CPM - Compatibility Mode -
Integer
- Controls the degree of compatibility between versions of the Streamlines
utility prior to NCAR Graphics 3.2 and the current version. You can
independently control three behaviors using the nine settings
provided:
- use of STRMLN input parameters;
- use of variables contained in the common blocks STR02 and STR03;
- use of the old coordinate mapping routines, FX and FY.
-
- Note, however, that when using the Version 3.2 entry points STINIT and
STREAM, only the third behavior option has any meaning.
When CPM is set to 0, its default value, the Streamlines
utility´s behavior varies depending on whether you access it
through one of the pre-Version 3.2 entry points (STRMLN and EZSTRM), or
through the STINIT/STREAM interface. Otherwise, positive values result
in invocation of the older coordinate mapping routines (FX and FY).
Negative values cause the Version 3.2 mapping routines to be used
instead. When using the pre-Version 3.2 interface only, odd values of
CPM cause the data values in the common blocks, STR02 and STR03, to
override corresponding values initialized in the Version 3.2 STDATA
block data subroutine, or set by the user calling STSETx routines.
Values of CPM with absolute value less than or equal to two cause the
NSET argument to STRMLN to take precedence over the SET parameter.
Here is a table of the nine settings of CPM and their effect
on the operation of the Streamlines utility:
Value |
Use FX and FY |
Use STR02,STR03 |
Use NSET |
----- |
------------- |
--------------- |
-------- |
-4 |
no |
no |
no |
-3 |
no |
yes |
no |
-2 |
no |
no |
yes |
-1 |
no |
yes |
yes |
0 |
old - yes;new - no (*) |
yes |
yes |
1 |
yes |
yes |
yes |
2 |
yes |
no |
yes |
3 |
yes |
yes |
no |
4 |
yes |
no |
no |
(*) Old means EZSTRM or STRMLN entry point; new,
STINIT/STREAM. Only the first column is applicable to the behavior of
the STINIT/STREAM interface. See the strmln man page for more detailed
emulation information.
- DFM - Streamline Differential
Magnitude
- DFM specifies the length of the differential magnitude step size used by
Streamlines. If the parameter GBS is set to 0 DFM has units "fraction
of viewport width"; if GBS is set to 1, DFM has the units
"fraction of grid box width". When the Version 3.2 mapping
routines are used, DFM directly affects processing time and the resulting
plot precision. In general, smaller values of DFM cause Streamlines to
take more, smaller steps in the construction of a streamline, resulting,
within the limits of the processor´s floating point resolution, in
longer execution times and a more precise plot. Process memory
requirements are not affected. If the compatibility mode parameter is set
such that the older mapping routines, FX and FY, are invoked instead, DFM
no longer has any effect on the plot, since in this case the step size is
determined by the setting of the parameter VNL as a fraction of the grid
box width. The default value of DFM is 0.02 when GBS has the value 0 and
0.33 when GBS has the value 1. Setting GBS causes DFM to be reset to its
appropriate default value.
- GBS - Grid-Based Spacing -
Real
- The parameter GBS controls the interpretation of several parameters that
play a critical role in the appearance of the streamline plot. These
parameters are DFM, SSP, and ARL. When GBS has the value 0, the values of
these parameters are treated as having units of "fraction of viewport
width". If GBS has the value 1, the values are treated as having the
units of "fraction of grid box width". Whenever you set GBS, the
three affected parameters are reset to default values appropriate to the
units; therefore you must set GBS prior to setting any non-default values
for DFM, SSP, or ARL. You may find that using the grid-based spacing
method causes Streamlines to adapt more gracefully to variations in the
density of the data grid. Currently, the default value of GBS is 0;
however, in the next release this may change.
- LWD - Streamline Linewidth -
Real
- LWD controls the linewidth used to draw the streamlines. Note that since
the linewidth in NCAR Graphics is always calculated relative to a unit
linewidth that is dependent on the output device, you may need to adjust
the linewidth value depending on the output conditions to obtain a
pleasing plot. LWD affects the linewidth of the directional arrowheads as
well as the streamlines themselves. The arrowhead length also increases
somewhat when the linewidth is greater than the default. However, the
arrowhead length parameter still affects the length. The default is 1.0,
specifying a device-dependent minimum linewidth.
- MAP - Map Transformation Code -
Integer
- MAP defines the mapping transformation between the data and user
coordinate space. For more information on coordinate mapping
transformations see the stuixy, stumxy, and stumta man pages, as well as
the description of the transformation type parameter, TRT. Three MAP
parameter codes are reserved for pre-defined transformations, as
follows:
- Value
- Mapping transformation
- 0 (default)
- Identity transformation between data and user coordinates: array indices
of U and V are linearly related to user coordinates. Note however that a
non-linear transformation is still possible from user to NDC
coordinates.
- 1
- Ezmap transformation: first dimension indices of U and V are linearly
related to longitude; second dimension indices are linearly related to
latitude.
- 2
- Polar to rectangular transformation: first dimension indices of U and V
are linearly related to the radius; second dimension indices are linearly
related to the angle in degrees.
-
- If MAP has any other value, Streamlines invokes the user-modifiable
subroutines, STUMXY, STUIXY, and STUMTA to perform the mapping. The
default version of these routines simply performs an identity mapping.
Note that, while the Streamlines utility does not actually prohibit the
practice, you are advised not to use negative integers for user-defined
mappings, since other utilities in the NCAR Graphics toolkit attach a
special meaning to negative mapping codes.
For all the predefined mappings, the linear relationship
between the grid array indices and the data coordinate system is
established using the four parameters, XC1, XCM, YC1, and YCN. The X
parameters define a mapping for the first and last indices of the first
dimension of the data arrays, and the Y parameters do the same for the
second dimension. If MAP is set to a value of one, you need to be
careful to ensure that the SET parameter is given a value of zero, since
the Ezmap routines require a specific user coordinate space for each
projection type, and internally call the SET routine to define the user
to NDC mapping. Otherwise, you may choose whether or not to issue a SET
call prior to calling STINIT, modifying the value of SET as required.
See the description of the parameter, TRT, and the man pages, stumxy,
stuixy, and stumta for more information.
- MSK - Mask To Area Map Flag -
Integer
- Use this parameter to control masking of streamlines to an existing area
map created by routines in the Areas utility. When MSK is greater than 0,
masking is enabled and an area map must be set up before calling STREAM.
The area map array and, in addition, the name of a user-definable masked
drawing routine, must be passed as input parameters to STREAM. There are
two states for the MSK parameter, as follows:
- Value
- Effect
- <= 0 (default)
- No streamline masking.
- >0
- The subroutine ARDRLN is called internally to decompose the streamlines
into segments contained entirely within a single area group. ARDRLN calls
the user-definable masked drawing subroutine.
-
- See the man page, stumsl, for further information on the user-definable
masked drawing subroutine.
- PLR - Polar Input Mode -
Integer
- When PLR is greater than zero, the vector component arrays are considered
to contain the field data in polar coordinate form: the U array is treated
as containing the vector magnitude and the V array as containing the
vector angle. Be careful not to confuse the PLR parameter with the MAP
parameter polar coordinate mode. The MAP parameter relates to the location
of the vector, not its value. Here is a table of values for PLR:
- Value
- Meaning
- 0 (default)
- U and V arrays contain data in cartesian component form.
- 1
- U array contains vector magnitudes; V array contains vector angles in
degrees.
- 2
- U array contain vector magnitudes; V array contains vector angles in
radians.
-
- You must initialize Streamlines with a call to STINIT after modifying this
parameter.
- SET - SET Call Flag -
Integer
- Give SET the value 0 to inhibit the SET call STINIT performs by default.
Arguments 5-8 of a SET call made by the user must be consistent with the
ranges of the user coordinates expected by Streamlines. This is determined
by the mapping from grid to data coordinates as specified by the values of
the parameters XC1, XCM, YC1, YCN, and also by the mapping from data to
user coordinates established by the MAP parameter. You must initialize
Streamlines with a call to STINIT after modifying this parameter. The
default value of SET is 1.
- SGD - Stream Starting Grid
Increment - Integer
- This parameter gives you a degree of control over the number and density
of streamlines in the field flow plot. The Streamlines utility never
begins a streamline in any grid box that has previously had a streamline
pass through it, where a grid box is defined as the space between adjacent
integer grid coordinates in the grid coordinate system along both
dimensions. By setting SGD to a value greater than 1, you can reduce the
number of grid boxes initially eligible for starting a streamline. A grid
box is considered initially eligible for starting a streamline only if
both the lesser indices that establish the grid box, modulo the value of
SGD, equal 0. If SGD is set to 2, for instance, every grid box with
even-numbered lower grid indices would be initially eligible for starting
a streamline. As the streamlines grow and pass through grid boxes that
were initially eligible, these boxes too are marked ineligible, further
reducing the boxes where a stream can be started.
If the transformation pipeline is everywhere linear from grid
coordinate space to NDC space, then this scheme for starting streamlines
usually produces a more or less uniform spacing of the streamlines over
the field flow plot. However, if there are non-linear transforms
anywhere in the pipeline, the streamlines will probably be more crowded
in some areas than in others. Future enhancements to the Streamlines
utility are expected to address this issue, and also perhaps to provide
options for intentional non-uniform spacing based on flow intensity. The
default value of SGD is 2.
- SSP - Streamline Spacing Value -
Real
- The streamline spacing parameter establishes the minimum distance a
streamline in progress is allowed to approach existing streamlines before
being terminated. If the parameter GBS is set to 0, SSP has units
"fraction of viewport width"; if GBS is set to 1, SSP has the
units "fraction of grid box width". In general, within either
system of units, larger values of SSP increase the distance between
streamlines, and have a tendency to create more, but shorter stream lines.
The spacing is only checked at intervals, so streamlines sometimes
approach closer than the specified distance. The checking frequency is
adjustable using the streamline crossover checking parameter, CKX. The
streamline starting grid increment parameter, SGD, also affects the
overall streamline density. The default value of SSP is 0.015 when GBS has
the value 0 and 0.5 when GBS has the value 1. Setting GBS causes SSP to be
reset to its appropriate default value.
- SST - Streamline Statistics
Output Flag - Integer
- If SST is set to one, STREAM writes a summary of its operations to the
default logical output unit, including the number of streamlines plotted
and the total differential step count. Here is a sample of the
output:
STREAM Statistics
Streamlines plotted: 119
Total differential step count: 2903
-
- The differential step count actually counts the number of iterations
through the main streamline construction loop, and can be used to help
gauge the trade-offs between the increased processing time required for
smaller differential step sizes and the resulting differences in plot
quality.
- SVF - Special Value Flag -
Integer
- The special value flag controls special value processing for the U and V
vector component data arrays. Special values may appear in either the U or
V array or in both of them. When any of the four points surrounding the
current streamline end contain a special value, the streamline is
terminated, and a new one started, if possible. Streamlines allows special
value processing to be turned on or off, as follows:
- Value
- Effect
- 0 (default)
- Neither the U nor the V array is examined for special values
- non 0
- Whenever the streamline under construction enters a new grid box, the U
and V array values at each corner of the box are examined for special
values. The interpolation method parameter, TRP, is overridden, causing
Streamlines to use bi-linear interpolation only.
-
- The U and V special values are defined by setting parameters USV and VSV.
Streamlines only uses bi-linear interpolation when special value
processing is in effect, because the Bessel interpolation method
quadruples the requirement for good data points (from 4 to 16) surrounding
the current stream end point. You must initialize Streamlines with a call
to STINIT after modifying this parameter.
- TRP - Interpolation Method -
Integer
- Use TRP to control which of two interpolation methods Streamlines should
use in determining the normalized flow components for each point in the
streamline. The choices are as follows:
- Value
- Interpolation Method
- 0 (default)
- Use the 16-point Bessel interpolation method where possible; otherwise,
near the data set boundaries use 12, 9 or 4 point interpolation methods,
depending on the situation.
- non 0
- Use 4-point bi-linear interpolation at all points.
-
- Note that Streamlines forces use of the 4-point bi-linear interpolation
method if the SVF parameter is set to turn on special value
processing.
- TRT - Transformation Type -
Integer
- The transformation type parameter, TRT, qualifies the mapping
transformation specified by the MAP parameters, as follows:
- Value
- Effect
- -1
- Direction, magnitude, and location are all transformed. This option is not
currently supported by any of the pre-defined coordinate system
mappings.
- 0
- Only location is transformed
- 1 (default)
- Direction and location are transformed
-
- This parameter allows you to distinguish between a system that provides a
mapping of location only into an essentially cartesian space, and one in
which the space itself mapped. To understand the difference, using polar
coordinates as an example, imagine a set of wind speed monitoring units
located on a radial grid around some central point such as an airport
control tower. Each unit´s position is defined in terms of its
distance from the tower and its angular direction from due east. However,
the data collected by each monitoring unit is represented as conventional
eastward and northward wind components. Assuming the towers´s
location is at a moderate latitude, and the monitoring units are
reasonably ´local´, this is an example of mapping a radially
defined location into a nearly cartesian space (i.e. if the northward
components were all set to 0.0, the streamlines defined by the eastward
components would all be parallel straight lines. One would set MAP to two
(for the polar transformation) and TRT to zero to model this data on a
plot generated by the Streamlines utility.
On the other hand, picture a set of wind data, again given as
eastward and northward wind components, but this time the center of the
polar map is actually one of the earth´s poles. In this case, the
eastward components do not point in a single direction; instead they
outline a series of concentric circles around the pole. This is a space
mapping transformation: one would again set MAP to two, but TRT would be
set to one to transform both direction and location.
Changing the setting of this parameter affects the end results
only when a non-uniform non-linear mapping occurs at some point in the
transformation pipeline. For this discussion a uniform linear
transformation is defined as one which satisfies the following
equations:
x_out = x_offset + scale_constant * x_in
y_out = y_offset + scale_constant * y_in
-
- If scale_constant is not the same for both equations then the mapping is
non-uniform.
This option is currently implemented only for the pre-defined
MAP parameter codes, 0 and 2, the identity mapping and the polar
coordinate mapping. However, it operates on a different stage of the
transformation pipeline in each case. The polar mapping is non-linear
from data to user coordinates. The identity mapping, even though
necessarily linear over the data to user space mapping, can have a
non-uniform mapping from user to NDC space, depending on the values
given to the input parameters of the SET call. This will be the case
whenever the LL input parameter specifies a logarithmic scaling or the
viewport and the user coordinate boundaries do not have the same aspect
ratio. Thus for a MAP value of 2, TRT affects the mapping between data
and user space, whereas for MAP set to 0, TRT influences the mapping
between user and NDC space.
- USV - U Array Special Value -
Real
- USV is the U vector component array special value. It is a value outside
the range of the normal data used to indicate that there is no valid data
for this grid location. When the special value flag parameter, SVF, is
non-zero, each time a streamline enters a new cell Streamlines will check
for this special value in the U array at each of the four corners of the
grid box. Anytime the special value is discovered, the current streamline
is terminated and a new one started if possible. The default value given
to USV is 1.0 * 10**12.
- VNL - Vector Normalization Value
- Real
- The parameter, VNL, determines the value Streamlines uses to normalize the
vector flow field, before beginning the streamline construction loop. When
Streamlines is used with the pre-Version 3.2 mapping routines, FX and FY,
the value of VNL determines the step size in the grid coordinate system
used to construct the streamlines, as a fraction of the grid box size.
When using FX and FY, smaller values of VNL result in smaller steps, more
processing time and, within the limits of the processor´s floating
point accuracy, a higher precision plot. However, if the mapping has
non-linearities, the grid size does not remain constant over the
transformation and the step size can vary greatly, resulting in
discontinuities in certain areas of the plot.
Streamline´s new mapping routines define the streamline
differential magnitude in NDC space, ensuring a constant step size over
the whole plot, notwithstanding any non-linearity in the transformation.
When using the new mapping routines, the parameter DFM controls the step
size in NDC space, and VNL is not adjustable by the user. (See the
discussion of the compatibility mode parameter, CPM, for a discussion of
how to switch between the old and new mapping routines.) The default
value of VNL is 0.33.
- VPB - Viewport Bottom -
Real
- The parameter VPB has an effect only when SET is non-zero, specifying that
Streamlines should do the call to SET. It defines a minimum boundary value
for the bottom edge of the viewport in NDC space, and is constrained to a
value between 0.0 and 1.0. It must be less than the value of the Viewport
Top parameter, VPT. The actual value of the viewport bottom edge used in
the plot may be greater than the value of VPB, depending on the setting of
the Viewport Shape parameter, VPS. You must initialize Streamlines with a
call to STINIT after modifying this parameter. The default value of VPB is
0.05.
- VPL - Viewport Left -
Real
- The parameter VPL has an effect only when SET is non-zero, specifying that
Streamlines should do the call to SET. It defines a minimum boundary value
for the left edge of the viewport in NDC space, and is constrained to a
value between 0.0 and 1.0. It must be less than the value of the Viewport
Right parameter, VPR. The actual value of the viewport left edge used in
the plot may be greater than the value of VPL, depending on the setting of
the Viewport Shape parameter, VPS. You must initialize Streamlines with a
call to STINIT after modifying this parameter. The default value of VPL is
0.05.
- VPR - Viewport Right -
Real
- The parameter VPR has an effect only when SET is non-zero, specifying that
Streamlines should do the call to SET. It defines a maximum boundary value
for the right edge of the viewport in NDC space, and is constrained to a
value between 0.0 and 1.0. It must be greater than the value of the
Viewport Left parameter, VPL. The actual value of the viewport right edge
used in the plot may be less than the value of VPR, depending on the
setting of the Viewport Shape parameter, VPS. You must initialize
Streamlines with a call to STINIT after modifying this parameter. The
default value of VPR is 0.95.
- VPS - Viewport Shape -
Real
- The parameter VPS has an effect only when SET is non-zero, specifying that
Streamlines should do the call to SET; it defines the desired viewport
shape, as follows:
- Value
- Effect
- <0.0
- The absolute value of VPS specifies the shape to use for the viewport, as
the ratio of the viewport width to its height,
- 0.0
- The viewport completely fills the area defined by the boundaries
specifiers, VPL, VPR, VPB, VPT
- >0.0,<1.0 (0.25,default)
- Use R = (XCM-XC1)/(YCN-YC1) as the viewport shape if MIN(R, 1.0/R) is
greater than VPS. Otherwise determine the shape as when VPS is equal to
0.0.
- >= 1.0
- Use R = (XCM-XC1)/(YCN-YC1) as the viewport shape if MAX(R, 1.0/R) is less
than VPS. Otherwise make the viewport a square.
-
- The viewport, whatever its final shape, is centered in, and made as large
as possible in, the area specified by the parameters VPB, VPL, VPR, and
VPT. You must initialize Streamlines with a call to STINIT after modifying
this parameter.
- VPT - Viewport Top -
Real
- The parameter VPT has an effect only when SET is non-zero, specifying that
Streamlines should do the call to SET. It defines a maximum boundary value
for the top edge of the viewport in NDC space, and is constrained to a
value between 0.0 and 1.0. It must be greater than the value of the
Viewport Bottom parameter, VPB. The actual value of the viewport top edge
used in the plot may be less than the value of VPT, depending on the
setting of the Viewport Shape parameter, VPS. You must initialize
Streamlines with a call to STINIT after modifying this parameter. The
default value of VPT is 0.95.
- VSV - V Array Special Value -
Real
- VSV is the V vector component array special value. It is a value outside
the range of the normal data used to indicate that there is no valid data
for this grid location. When the special value flag parameter, SVF, is
non-zero, each time a streamline enters a new cell Streamlines will check
for this special value in the V array at each of the four corners of the
grid box. Anytime the special value is discovered, the current streamline
is terminated and a new one started if possible. You must initialize
Streamlines with a call to STINIT after modifying this parameter. The
default value given to VSV is 1.0 * 10**12.
- WDB - Window Bottom -
Real
- When STINIT does the call to SET, the parameter WDB is used to determine
argument number 7, the user Y coordinate at the bottom of the window. If
WDB is not equal to WDT, WDB is used. If WDB is equal to WDT, but YC1 is
not equal to YCN, then YC1 is used. Otherwise, the value 1.0 is used. You
must initialize Streamlines with a call to STINIT after modifying this
parameter. The default value of WDB is 0.0.
- WDL - Window Left -
Real
- When STINIT the call to SET, the parameter WDL is used to determine
argument number 5, the user X coordinate at the left edge of the window.
If WDL is not equal to WDR, WDL is used. If WDL is equal to WDR, but XC1
is not equal to XCM, then XC1 is used. Otherwise, the value 1.0 is used.
You must initialize Streamlines with a call to STINIT after modifying this
parameter. The default value of WDL is 0.0.
- WDR - Window Right -
Real
- When STINIT does the call to SET, the parameter WDR is used to determine
argument number 6, the user X coordinate at the right edge of the window.
If WDR is not equal to WDL, WDR is used. If WDR is equal to WDL, but XCM
is not equal to XC1, then XCM is used. Otherwise, the value of the STINIT
input parameter, M, converted to a real, is used. You must initialize
Streamlines with a call to STINIT after modifying this parameter. The
default value of WDR is 0.0.
- WDT - Window Top - Real
- When STINIT does the call to SET, the parameter WDB is used to determine
argument number 8, the user Y coordinate at the top of the window. If WDT
is not equal to WDB, WDT is used. If WDT is equal to WDB, but YCN is not
equal to YC1 then YCN is used. Otherwise, the value of the STINIT input
parameter, N, converted to a real, is used. You must initialize
Streamlines with a call to STINIT after modifying this parameter. The
default value of WDT is 0.0.
- XC1 - X Coordinate at Index 1 -
Real
- The parameter XC1 specifies the X coordinate value that corresponds to a
value of 1 for the first subscript of the U and V, vector field component
arrays. Together with XCM, YC1, and YCN it establishes the mapping from
grid coordinate space to data coordinate space. If XC1 is equal to XCM,
1.0 will be used. You must initialize Streamlines with a call to STINIT
after modifying this parameter. The default value of XC1 is 0.0.
- XCM - X Coordinate at Index M -
Real
- The parameter XCM specifies the X coordinate value that corresponds to the
value of the STINIT input parameter, M, for the first subscript of the U
and V vector component arrays. Together with XC1, YC1, and YCN it
establishes the mapping from grid coordinate space to data coordinate
space. If XC1 is equal to XCM, the value of M, converted to a real, will
be used. You must initialize Streamlines with a call to STINIT after
modifying this parameter. The default value of XCM is 0.0
- YC1 - Y Coordinate at Index 1 -
Real
- The parameter YC1 specifies the Y coordinate value that corresponds to a
value of 1 for the first subscript of the U, V, vector component arrays as
well as for the P scalar data array, if used. Together with YCN, XC1, and
XCM it establishes the mapping from grid coordinate space to data
coordinate space. If YC1 is equal to YCN, 1.0 will be used. You must
initialize Streamlines with a call to STINIT after modifying this
parameter. The default value of YC1 is 0.0
- YCN - Y Coordinate at Index N -
Real
- The parameter YCN specifies the Y coordinate value that corresponds to the
value of the STINIT input parameter, N, for the second subscript of the U
and V vector component arrays as well as the P scalar data array, if used.
Together with YC1, XC1, and XCM it establishes the mapping from grid
coordinate space to data coordinate space. If YC1 is equal to YCN, the
value of N, converted to a real, will be used. You must initialize
Streamlines with a call to STINIT after modifying this parameter. The
default value of YCN is 0.0
- ZFC - Zero Field Text Block
Color - Integer
- If ZFC is greater or equal to zero, it specifies the GKS color index to
use to color the Zero Field text block. Otherwise the Zero Field text
block is colored using the current GKS text color index. The default value
of ZFC is -1.
- ZFP - Zero Field Text Block
Positioning Mode - Integer
- The ZFP parameter allows you to justify, using any of the 9 standard
justification modes, the Zero Field text block unit with respect to the
position established by the parameters, ZFX and ZFY The position modes are
supported as follows:
- Mode
- Justification
- -4
- The lower left corner of the text block is positioned at ZFX, ZFY.
- -3
- The center of the bottom edge is positioned at ZFX, ZFY.
- -2
- The lower right corner is positioned at ZFX, ZFY.
- -1
- The center of the left edge is positioned at ZFX, ZFY.
- 0 (default)
- The text block is centered along both axes at ZFX, ZFY.
- 1
- The center of the right edge is positioned at ZFX, ZFY.
- 2
- The top left corner is positioned at ZFX, ZFY.
- 3
- The center of the top edge is positioned at ZFX, ZFY.
- 4
- The top right corner is positioned at ZFX, ZFY.
- ZFS - Zero Field Text Block
Character Size - Real
- ZFS specifies the size of the characters used in the Zero Field graphics
text block as a fraction of the viewport width. The default value is
0.033.
- ZFT - Zero Field Text String -
Character* 36
- Use ZFT to modify the text of the Zero Field text block. The Zero Field
text block may appear whenever the U and V vector component arrays contain
data such that all the grid points otherwise eligible for plotting contain
zero magnitude vectors. Currently the string length is limited to 36
characters. Set ZFT to a single space (´ ´) to prevent the
text from being displayed. The default value for the text is ´Zero
Field´.
- ZFX - Zero Field Text Block X
Coordinate - Real
- ZFX establishes the X coordinate of the Zero Field graphics text block as
a fraction of the viewport width. Values less than 0.0 or greater than 1.0
are permissible and respectively represent regions to the left or right of
the viewport. The actual position of the block relative to ZFX depends on
the value assigned to the Zero Field Positioning Mode parameter, ZFP. The
default value is 0.5.
- ZFY - Zero Field Text Block Y
Coordinate - Real
- ZFY establishes the Y coordinate of the minimum vector graphics text block
as a fraction of the viewport height. Values less than 0.0 or greater than
1.0 are permissible and respectively represent regions below and above the
viewport. The actual position of the block relative to ZFY depends on the
value assigned to the Zero Field Positioning Mode parameter, ZFP. The
default value is 0.5.
Online: stgetc, stgeti, stgetr, stinit, stream, streamlines,
strset, stsetc, stseti, stsetr, stuixy, stumsl, stumta, stumxy,
ncarg_cbind.
Hardcopy: NCAR Graphics Fundamentals, UNIX Version
Copyright (C) 1987-2009
University Corporation for Atmospheric Research
The use of this Software is governed by a License Agreement.