Sylvan Stand Structure Models

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Model Function Lookup Tables

The Sylvan Stand Structure Model stores functions in a function lookup table. The following is a illustration to help you understand how diverse functional forms can be stored in a common standardized format. In figure is a model form from a published function. The image is a screenshot of the function display for this model form. To see the the actual Functions page click on the functions link in the sidebar.

Screenshot from tha published function

Figure 1. An example of our published function webpage with a particulate function and species selected.

If the user want to use this published function, we use thei equation to generate a set of (x,y) points that describe the line, This is the same way we would generate (x,y) point to plot the line for the graph in Figure 2.

Graph of the function in Figure 1

Figure 2. A graph of the function for a range of x values.

The (x,y) point are then standardized and and the scale data and the standardized points are stored in the database. Figure 3. is an example of the some of thes point for the same equation.

Screen shot of the database table for the function in Figure 3

Figure 3. An example of how the data to product the graph is stored in the database. Note that an error component cane be added if the information is available.

This approach allow the user to have a high degree of flexibilty as any functional form can be store in the standarized lookup table and use with function of very different forms.


Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial 3.0 United States License.

Author: Dr. David R. Larsen
Created: April 3, 2009
Last Updated: April 3, 2009