Second Harmonic Generation

gnuplot> set xrange [-180:180]

gnuplot> set yrange [-180:180]

gnuplot> set pm3d

gnuplot> set hidden3d 

gnuplot> set title 'SHG'

gnuplot> splot sin(cos(x*pi/180))*sin(cos(x*pi/180))/(cos(x*pi/180)*cos(x*pi/180))*sin(cos(y*pi/180))*sin(cos(y*pi/180))/(cos(y*pi/180)*cos(y*pi/180)) title 'N=1

'