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8.3.1.3 Exponential

General Form:

          EXP(V1 V2 TD1 TAU1 TD2 TAU2)

Examples:

          VIN 3 0 EXP(-4 -1 2NS 30NS 60NS 40NS)
     parameter                   default value   units
     ---------------------------------------------------------
     V1   (initial value)                        Volts or Amps
     V2   (pulsed value)                         Volts or Amps
     TD1  (rise delay time)      0.0             seconds
     TAU1 (rise time constant)   TSTEP           seconds
     TD2  (fall delay time)      TD1+TSTEP       seconds
     TAU2 (fall time constant)   TSTEP           seconds

The shape of the waveform is described by the following table:

     time           value
     ---------------------------------------------------------------------
     0 to TD1      V1
                                |    -(t - TD1)|
     TD1 to TD2    V1 + (V2-V1).|1-e ----------|
                                |       TAU1   |
     
                                |    -(t - TD1)|           |   -(t - TD2)|
     TD2 to TSTOP  V1 + (V2-V1).|1-e ----------| + (V1-V2).|1-e ---------|
                                |        TAU1  |           |       TAU2  |