Calculate the Q function values for a real-valued input vector.

x = -4:0.1:4; y = qfunc(x);

Plot the results.

plot(x,y) grid

Calculate the QPSK error probability at an ${\mathit{E}}_{\mathrm{b}}/{\mathit{N}}_0$setting of 7 dB by using the Q function.

Convert the ${\mathit{E}}_{\mathrm{b}}/{\mathit{N}}_0$in dB to its linear equivalent.

ebnodB = 7; ebno = 10^(ebnodB/10);

Using the Q function, calculate the QPSK error probability, $$P_b=Q\left(\sqrt{2\frac{E_b}{N_0}}\right)$$.

Pb = qfunc(sqrt(2*ebno))

Pb = 7.7267e-04