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Two Dimensional Graphs
Tecplot is very flexible when drawing graphs. It can do the following, the ones with links are discussed in this document.
- Basic XY Plots
- Assign a variable to an axis
- Change the length and scale of the axes
- Plot multiple data sets.
- Plot multiple graphs, multiple axis
- Plot multiple data sets.
- Scatter plots , with choice of symbols.
- 3D graphs
To draw a graph using tecplot, just read in your one dimensional data . The graph will appear similar to the one shown below.
There are many things that you can do with the graph. Click on the "Mapping Style..." button. If you don't see the "Mapping Style..." button, double click on the graph. When you click on the "Mapping style..." button, you will see the following.
From this menu, you can control how the graph is plotted. The various features are broken down by category: "Definitions", "Lines", "Curves","Symbols", .... To select the category, click on the appropriate button. The categories, definitions, lines and symbols are discused below.
- Definitions: You can assign a variable to the x-axis and to the y-axis. To assign a variable to the y-axis, just click on "Y-Axis Variable". A window will pop up. Choose the variable that you to use for the vertical axis. The x-axis is handled in a similar manner.
- Lines: Select the "Lines" category to set line color, line width, line style (Solid, dotted, dashed, ...), line color and more. Just point and click.
- Symbols (Scatter Plots): To show a symbol (square, circle) at the data points, click on the box next to "Symbols" in the upper left corner of the tecplot window. If you just want to see symbols - no line connecting the points - unselect the "Lines" in the upper left corner. In the "Mapping style" window, click on "Symbols". You should see the following.
From here, you can select the symbol shape, outline color, fill color, size and spacing. Just click on the appropriate button. To control the spacing, click on "Symb Spacing" and then click on "Iskip=2", "Iskip=3" or "Iskip=4" which will draw the symbol at every second, third or fourth point respectively. If this is still too many. Use the "Enter Index..." option to manually enter a skip value.
To adjust the axes, including tick marks, labels, and length, pull the "Axis" menu down from "Plot" menu. You will see the following
Across the top, is a list of axes that you can display and modify. Select the desired axis. In the above the "X1" axis is selected. A modification occurs only on the selected axis.
Here everything but range is easy to use, just remember "Labels" means the numbers that appear next to the tick marks, and "Title" means the name of the variable.
The range option can be confusing.
- If one of the axis is too long, you can change the range. There are several things to set before you change the range. Unselect "Preserve Length when Changing Range" and select "Independent".
- If you want to change the range to zoom in, select "Preserve Length when Changing Range" and select "Dependent". You may have to enter a ratio to determine the scale of the axis.
- You can also change the scale by selecting the arrow from the tools palette, clicking on an axis, then dragging a resize handle (a black square) to change the size of the plot. Note: This changes the scale of all axes.
Preserving the length keeps the axis the same length, the scale changes.
Tecplot can plot multiple data sets. The easiest way to plot multiple data sets is to create a file containing all the data set, each data set is a zone in the file. In the "Mapping style" window, you can turn on and off various zones. Just click on the desired zone (that is, click on the line that are listed by map number), or click and drag to choose multiple zones, then click on the "Map Show" button. You can then activate or deactivate the selected zone(s).
You can also plot multiple data sets that are in different files. The easiest way to do this is to read all the data sets in at once.
Pull the "File" menu down to "Load Data File(s)...". You will see the following window.
- Click on "Multiple Files". This window will change. Enter the name of each of the file that you want to read in. Between each file either press the return key or click on the "Add" button. When all files have been selected, press "OK".
- The first file will be plotted. To plot the other files, click on ""Mapping style..." Select the desired data set - each data set is assigned a map number corresponding the order that you selected the data files - by clicking on the line containing the desired map or by clicking and dragging to select multiple maps. Now click on the "Map Show" button and activate or deactivate.
- You may have to pull the "View Menu" down to "Data Fit" to view all the data sets.
You can show multiple axis when you have multiple data sets
In the "Mapping style" window, select "Definitions". Now click on "Which Y-Axis" and select the appropriate axis. That's it. You can modify the new axis by pulling down the "Axis" menu from "Plot" and selecting the appropriate axis
Tecplot can draw three dimensional graphs. Read in your data, then click on the "3D cartesian" from the pull down menu in the upper left corner of the tecplot window, then redraw. As with 2D graphs, you can modify with the axis labels, major and minor grid marks, grid background. To do so, pull down the "Axis" menu from "Plot". Click on the desired button and enter the desired settings for each axi