How we can represent a bandpass signal equation in matlab
Usually (almost always), simulation is done using the discrete time baseband signal. Lets say you want to simulate 32 BPSK symbols (either +1 or -1). The MATLAB code for this is:

 symbols = sign( rand(32, 1) - 0.5 ); 

Now that you have the symbols, the next step is to upsample. You can either use the MATLAB function or do it yourself:

 symbols_up = upsample(symbols, samplesPerSymbol); 

Then create and use a pulse shaping filter (just use rcosdesign):

 pulseFilter = rcosdesign(rolloff, span, samplesPerSymbol, 'sqrt');
  txSig = filter(pulseFilter, 1, symbols_up); 
  figure, plot(txSig)