The shape of the waveform is described by the following table:
parameters default values 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
time value 0 v1 td1 v1 + (v2-v1)(1 - exp(-(time-td1)/tau1)) td2 v1 + (v2-v1)(1 - exp(-(time-td1)/tau1)) + (v1-v2)(1 - exp(-(time-td2)/tau2))
This function applies only to transient analysis, where time is the running variable. When referring to default values, tstep is the printing increment and tstop is the final time in transient analysis, see 2.7.9 for explanation. The argument count is used to distinguish this function from the math function of the same name.