Analysing Monte-Carlo Results

In this topic:

Plots

Plots of Monte Carlo analyses are performed in exactly the same manner as for normal runs. When you probe a circuit point, curves for each run in the MC analysis will be created. You will notice, however, that only one label for each set of curves will be displayed. Operations on curves such as deleting and moving will be performed on the complete set.

Identifying Curves

Sometimes it is useful to know exactly which run a particular curve is associated with. To do this proceed as follows:

  1. Switch on graph cursors. (Cursors > Toggle On/Off menu)
  2. Pick up the main cursor (the one with the short dashes) and place it on the curve of interest. (To pick up a cursor, place mouse cursor at intersection, press left key and drag).
  3. Select Show Curve Info menu. Information about the curve will be displayed in the command shell.
This is an example of what will be displayed: 
Source group: ac1
Curve id: 4
Run number: 49

The information of interest here is the Run number. With this you can look up in the log file details of the run i.e. what values were used for each part and parameter. You can also obtain the seed value used so that the run can be repeated. See Setting the Seed Value.

Plotting a single Curve

If you wish to plot a single curve in a Monte Carlo set, you must obtain the run number then use the Probe > Add Curve... menu to plot an indexed expression. We use an example to explain the process.

Using the Chebyshev filter example, let's suppose that we wish to plot the curve of the filter output created by run 49 alone without the remaining curves. Proceed as follows.

  1. Run the chebyshev filter example as explained at the beginning of this chapter.
  2. Select menu Probe > Add Curve...
  3. Click on the output of the filter. You should see C4_P entered in the Y expression box.
  4. You must now modify the expression you have entered to give it an index value. For the simple case of a single voltage or current just append it with 
    [index]

    where index is the run number less 1. In this example the run number is 49 so we enter 48 for the index. You should now have: 
    C4_P[48]
    displayed in the Y expression box.
  5. Close box. You should see a single curve plotted.
An alternative method of plotting single curves is given in Setting the Seed Value.

Creating Histograms

See Performance Analysis and Histograms.

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