WAVES Gnuplot Help
The following information will help you use the Gnuplot interface. Beginning
users should focus on using the Basic Interface,
or the 2-Dimensional or
3 Dimensional Dynamic Interfaces.
Expert users can insert or create Gnuplot command
files in the text area provided on the
Expert Interface.
For the Basic Interface, help is broken up into Data Entry and Plot Options. In addition, Troubleshooting information
and Demo files
are also available.
Data Entry: On this portion of the form, you specify where your
data is located along with the data format. It is vital that the
Data Format, Plot Source, and Plot Source Type match up properly for
the interface to work.
Data Format: Select the data format which corresponds to your plot. Available
setting include 2-Dimensional Cartesian, 2-Dimensional Polar, and 3-Dimensional
Cartesian. Gnuplot requires data files to
be organized in a certain way to work properly. When using your own data,
by default Gnuplot uses the first column for 'x', the second column for 'y', and
the third column for 'z'. For example:
For more information about formatting your data, check out
the Gnuplot Homepage
, the Gnuplot Reference Manual
or the
Gnuplot FAQs. If your data does not correspond to the above format, check
out the "using" command in the Gnuplot Reference manual.
Plot Source: You can combine up to three plots which can be a combination of
functions, server side data files, remote data files, or data provided in one of the three "Data Areas."
To "activate" a plot, make sure the on/off radio button is selected. To turn a
plot off, make sure the on/off radio button is not selected; this will
cause any data in the text entry field to be ignored.
For details on how to enter plot sources in the text entry field, see the Plot Source Type section below.
Plot Source Type: The selection in this area tells the interface how to process the Plot Source
located to its immediate left (either Plot 1, Plot 2, or Plot 3). If the "Data Area" Plot Source Type is selected, the information in
the Plot Source text field will be ignored. The following is a brief definition of
the possible source types:
Function: The text field contains a function which is specified in terms of "x" and possibly "y" (for 3D plots).
2-D Cartesian functions are in the form y=f(x) and 3-D Cartesian functions
are in the form z=f(x,y).
2-D Polar coordinates are in the form r=f(theta), but the variable "x" is used
to represent the variable "theta". The default unit for "theta" is radians, but
you can change the unit to degrees by adding the command "set angle degree" to
the Gnuplot command file as detailed below in the "Additional Commands/Override Settings" section.
Example functions include:
2-D Cartesian: sin(x**2)+cos(x)
2-D Polar: sin(x)+cos(x)
3-D Cartesian: sin(x)*sin(y)/(x*y)
Server Data File: The text field contains the name of a file located in the
server data directory.
Remote Data File: The plot source is located in a remote data file. The file must me accessable on the Web using the "http://" protocal. The file must be a clear text file (not HTML) in the proper Gnuplot format. When entering the file's
location it is not necessary to type in "http://", simply enter the URL and file
name (i.e. "www.nacse.pdx.edu/Waves/Gnuplot/data/data3.dat")
Data Area: The plot source has been "cut & pasted" into a corresponding Data Area.
Note that Data Area 1 can only be viewed as Plot 1, and Data Area 2 can
only be viewed as Plot 2, etc. This option is the quickest way to
plot small data files.
Selecting this option will cause the interface to ignore any
data in the Plot Source text entry field.
Your data must correspond to the format shown above in the "Data Format" section. If you have column based data in a different format you may be able to
create your desired plot using the Expert Interface and the "using" command. (see the
Gnuplot Reference Manual, or the "using1.gp" demo file for more information.)
Plot Options: In this portion of the form you specify the options for the resulting plot. For basic plots refer to the following information:
Plot Style: This feature allows you to alter the way your data appears
when it is plotted. The options are Lines, Points, Lines & Points, Dots,
Steps, Boxes, and Impulses. This feature can be different for each
plot.
Plot Legend: Any text entered in this field will show up on the final plot
as the legend corresponding to the particular plot number. The Legend can also be
turned off as a "Basic Plot Feature."
Labels: These fields set the values for the final plot's labels. You
can set the title, x-axis, y-axis, and z-axis.
Basic Plot Features: Many basic plot features can be toggled on or off in this area.
The features are: x-axis, y-axis, tic marks, grid lines, border, color,
legend, and time. In addition, the size and aspect ratio of the final plot can be altered
using the "Plot Size Ratio" feature. The ratio is relative to the maximum
possible size (represented as "1.0") which can be obtained in the horizontal or
vertical direction.
Data Ranges: This entry area overrides the automatic range selection
offered by Gnuplot. If you are not satified with the automatic range settings,
simply enter your desired settings for the appropriate axis. For functions,
a data sampling rate can be set to override the default value of "100."
3D Options: For 3D plots, several features can be toggled on and off for
optimal results. Pertaining to the resulting surface, you can Remove Hidden Lines, or choose not to draw the surface at all (primarily for use with contour
lines). Additionally, contour lines can be drawn on the Base and/or the Surface,
they can be smoothed with a smoothing algorithm, and the labels for the contour lines can be turned on and off.
For surface plots, the number of isolines drawn on the plot can be adjusted
by changing the "Isoline Samplings." If the resulting 3D plot doesn't reveal the desired
area, the view of the observer can be adjusted by altering the View Rotation in
the x and z direction.
Additional Commands: Users familiar with Gnuplot
can use this area to supplement the settings in the form or
even to override setting on the form.
Ignore Commands Below: This setting prevents any commands in the
text area from being submitted by the form. Use this setting to turn-off any
commands you've added.
Add Commands Below to Current Form Settings: This setting adds all of
the commands in the text area to the current form settings. Since these
commands are added after the form settings, commands in this area will
override any equivalent settings on the form.
You may not use the system command, the cd command, the load or output
commands (for security reasons).
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NACSE at Portland State Universi
ty
Developed and Maintained by Tom Misley
Comments and Suggestions to: misley@ee.pdx.ed
u
Copyright © 1997, All Rights Reserved
Revised September 1, 1997
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