"Piecewise" waveform arithmetics in ltspice?

[teemuk]

Is there a way to combine several waveform arithmetic functions so that they would work at specific ranges of input x?

for example:
With values of x < -1 the waveform would be processed with function #1,
with values of x >-1 and <1 the waveform would be processed with function #2, and with values of x >1 the waveform would be processed with function #3.

[teemuk]

Nevermind, I can wrap it up with IF sentences.

If someone has a better solution let's hear ya.

[jcx]

the U() function can be used to turn on/off terms in an equation

my Spice simulation
sim uses the U() function to select different periods of a waveform for parts of the calculation:

V=u(time-{(ncycles-3)*period})*u({(ncycles-2)*period}-time) is unit pulse for one cycle of a waveform and can be multiplied by the funciton you want to select for that time range - other functions of I,V can be used as "window" control arguments