4.4EXP: Exponential time dependent value

4.4.1  Syntax

EXP args
EXP iv pv td1 tau1 td2 tau2 period

4.4.2  Purpose

The component value is an exponential function of time.

For voltage and current sources, this is the same as the Spice EXP function, with some extensions.

The shape of the waveform is described by the following algorithm:
```ev = _iv;
for (reltime=time; reltime>=0; reltime-=_period){
if (reltime > _td1){
ev += (_pv - _iv)
* (1. - Exp(-(reltime-_td1)/_tau1));
}
if (reltime > _td2){
ev += (_iv - _pv)
* (1. - Exp(-(reltime-_td2)/_tau2));
}
}
```
For other components, it gives a time dependent value.

As an extension beyond Spice, you may specify the parameters as name=value pairs in any order.

4.4.4  Parameters

IV = x
Initial value. (required)

PV = x
Pulsed value. (required)

TD1 = x
Rise time delay. (Default = 0.)

TAU1 = x
Rise time constant. (Default = 0.)

TD2 = x
Fall time delay. (Default = 0.)

TAU2 = x
Fall time constant. (Default = 0.)

Period = x
Repeat period. (Default = infinity.)