outsig=rampup(L);
rampup(L) will return a rising ramp function of length L. The ramp is a sinusoide starting from zero and ending at one. The ramp is centered such that the first element is always 0 and the last element is not quite 1, such that the ramp fits with following ones.
rampup(L,wintype) will use another window for ramping. This may be any of the window types from firwin. Please see the help on firwin for more information. The default is to use a piece of the Hann window.