why BPSK matlab coding is diff. than BPSK text book formula

im a newbie for digital communication. currently i hav an assignment regarding on BPSK & QPSK matlab. that hav sthgs which im not understanding btw matlab coding and text book formula.

as wat i read in text book, the BPSK transmitted signal is represented as

S_bpsk(t)=m(t)*√(2Eb/Tb)*cos(ωc*t)

but, in matlab coding (an example)

------------------------------------------------------------------------------------
Ns=100; %vector of length Ns symbols
data=2*round(rand(Ns,1))-1; %this converts 0 into -1, 1 into 1
bpsk=data;
------------------------------------------------------------------------------------

how come the matlab code using a simple -1 & 1 to represent BPSK transmitted signal? (kindly any intelligent can explained this question to me)

Re: why BPSK matlab coding is diff. than BPSK text book form

this ±1 corresponds to just the m(t) in the equation. You have to generate the carrier and mutliply it with your ±1 sequence to get the modulated signal.
-b

OOooo......now i understand, thk you for ur help...