Normalize values in a plot

Hey guys, thanks in advance,

I have this graph:

And I wish to normalize y axis , saying that maximum is 0dB. Im normalizing it like this:

maxval=max(X_QPSK_cut);
X_QPSK_cut=X_QPSK_cut/maxval;
fig=figure;
hold on
set(fig,'color','white');
plot(freq_XQPSK_cut,20*log10(X_QPSK_cut),'b','linewidth',2);
xlabel('Frequency [Hz]');
ylabel('QPSK Spectrum [dB]');
set(gca,'fontsize',fontsize);
grid on;
hold off

Is there a way of normalize the y axis , saying that max val is 0, because, if I put 0 it will say that vector is infinit, and that is true,

Thanks,

[Dyuman Joshi]

One way is to shift the whole data, by subtracting the max value from the data and then plotting.

[Miguel Albuquerque]

alright thanks

[dpb]

The above plot doesn't seem to represent the code (or vice versa)....if you actually normalized as the code says, the max cannot be -105 dB or whatever the max actually is on the plot.

Something's not kosher -- attach the data file as .mat file.

[Miguel Albuquerque]

Thanks dpb, I ve already solved it, I normalized with the max value of the plot, the plot in the figure, increased 110 dB.