Download and unzip the matlab_programs file into a file. Make this file your "Current directory" in Matlab. Type "btgui" in the Command window and hit return. Try different values of the parameters to see how T* changes in the Baumol Tobin model. Notice that the average money stock is calculated and check out how that changes with the parameters.
The Baumol_Tobin handout explains a bit about the program.