Processing S-parameter data by using matlab

Hi, I got lot of data in polar form and want to processing by creating a formula/program in matlab. Can anyone give me some advice.I am starter of Matlab.

For example ,

F(x) = [100*(S11)*(S22) + S12]/ S11

And i have lot of data of S11 ,S22 ,S12 in polar form

S11 Magnitude Phase

f=0.91GHz 10 120
f=0.92GHz 13 119
f=0.93GHz 15 110

S22 Magnitude Phase
f=0.91GHz 10 121
f=0.92GHz 12 119
f=0.93GHz 15 130

S12 Magnitude Phase
f=0.91GHz 12 121
f=0.92GHz 13 119
f=0.93GHz 12 110

After calculate F(x) on different value of S in f, i want to plot the graph in F(x) vs f.

The problem now is i don't know how to calculate polar form in matlab directly. I know the function of abs(ans) and angle(ans).But my data are in polar form not in complex.Do i need to convert it to complex first and how?

Thanks,

chowlong