Exercise Two

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To become familiar with some aspects of interacting with modules, including

  • Working with widgets
  • Connecting modules together
  • Adding new modules to a map


  1. Read2Da reads in 2D scalar or vector data from an ASCII file in a simple format and outputs a 2D uniform lattice. Load the file $EXPLORERHOME/data/NAG/zigzag.2D into Read2Da (where $EXPLORERHOME is the root directory of your IRIS Explorer installation). Either type the pathname in (do not forget to hit <Enter>), or pull down the file browser under the File menu item on the maximised control panel. What does the module do if you mistype the name of the file?
  2. Modules fire when all their inputs are satisfied. The title bar flashes yellow when the module is firing. What happens to Read2Da if you load the file again (hit <Enter> at the end of the filename in the text widget)?
  3. Maximise the Contour control panel. Check the default values for the limits on the minimum and maximum contour levels. Connect Read2Da's Lattice port to Contour's Input port. What happens to the limits when the connection is made?
  4. Set Num Levels to 7, and Min Level to -10.5. What does Contour do each time one of its parameters is changed? Connect Contour's Contours port to Render's Input port. Maximise the Render control panel to get a better view of the output.
  5. Set Max Level on Contour to exactly 3.0, and view the change to the output in the Render window. Try some other values for the parameters to Contour, and view the results.
  6. The WireFrame module creates a bounding box around a 2D lattice by calculating the limits of its coordinates. Find it in the Module Librarian, and load it into the Map Editor. Connect its Input port to the Lattice port on Read2Da, and its Output port to Render's Input port.

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© The Numerical Algorithms Group Ltd. Oxford, UK. 2000