Using exponential decay data to define an amplitude curve

Use the exponential decay definition method to define the amplitude, a, as

a=A0+Aexp(-(t-t0)/td)     for t≥t0,a=A0     for t<t0,

where A0, A, t0, and td are user-defined constants. For more information, see Defining exponential decay.

  1. Display the Edit Amplitude dialog box as described in Selecting an amplitude type to define.

  2. Click the arrow to the right of the Time span field, and specify how you want to define the amplitude as a function of time:

    • Select Step time for time that is measured from the beginning of each step.

    • Select Total time for total time accumulated over all non-perturbation analysis steps.

  3. In the Initial amplitude field, enter A0.

  4. In the Amplitude field, enter A.

  5. In the Starting time field, enter the start time of the exponential function, t0.

  6. In the Decay time field, enter the decay time of the exponential function, td.

  7. Click OK to save your amplitude definition and to close the Edit Amplitude dialog box.