Antenna Pattern Symmetric Null Steering / Beamforming

Hi!

I have an antenna made of N linear elements forming an array (N = 3). I want to compute the steering vector so that the maximum of the array factor points to the boresight (or a direction close-by), let's say at 0º, but I want to place a null at a certain direction (say at 15º), but I want to place this null symmetrically with respect to the main beam (so at +/- 15º). I think analytically this is difficult to achieve (one main direction and one null it is ok but not the two nulls) and probably a genetic algorithm solution would be best suited. However I'm not sure this is the best approach using Matlab (and how to use it) or if there are better built-in beamformers for this purpose (e.g. MVDR). Any clue on this topic would help me very much.

Thank you very much!