Created:
July 30, 2008

User Level:
Intermediate

Products:
HelixTree, CNAM

Step 2. Compute and Plot the Log of Eigenvalues

Once you have generated a list of eigenvalues the next step is to compute the log of the eigenvalues. To do this, first download the Log of Eigenvalues script from our Add-on Scripts Repository.

Save the script to in the following directory:
../HelixTree/scriptsHT/user/Spreadsheet/Scripts/

Next, open the eigenvalue spreadsheet created in Step 1. Select >Scripts >Log of Eigenvalues. This will create a new spreadsheet with three columns (Figure 1): an index (black), the untransformed eigenvalues (grayed out), and the log transformed eigenvalues (magenta).

To generate a scree plot of the log transformed eigenvalues (Figure 2) left click on the LogEigenvalue column header and select Plot This Column.

Eigenvalue Spreadsheet
Figure 1. Log transformed eigenvalue
spreadsheet.
Scree Plot
Figure 2. Scree plot of eigenvalues.