The shape of the waveform is described by the following table:
parameters default value units vo (offset) volts or amps vp (peak amplitude) volts or amps per (period) tstop seconds td (delay) 0.0 seconds decay (decay const) 0.0 1/seconds
time value 0 vo td vo + 0.5 . (vp-vo)( 1 - cos(2 . (time-td)/per) . exp(-(time-td) . decay) )
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.