y = ugauss2 (xsigma, ysigma, kx, ky)
Ugauss2(xsigma,ysigma,kx,ky) -- Generate a unit-area 2D gaussian envelope xsigma -- standard deviation in X ysigma -- standard deviation in Y kx -- number of sigmas to generate in X direction [6] ky -- number of sigmas to generate in Y direction [kx]