Predefined functions
a*sin(b*x-t): Plane wave x
a*sin(b*y-t): Plane wave y
0.3*sin(6*pi*a*(b*x+c*y)/sqrt(b*b+c*c)-t): Plane wave direction adjustable
a*(sin(b*y-t)+sin(b*y-t)): Interference concurrent f1
a*(sin(b*y-t)+sin(-b*y-t)): Interference countercurrent f1
a*(sin(b*y-t)+sin(c*y-t)): Interference concurrent f1 + f2
a*(sin(b*y-t)+sin(-c*y-t)): Interference countercurrent f1 + f2
a*(sin(b*x-t)+sin(c*y-t)): Interference perpendicular f1 + f2
a*(sin(b*(y-(c-pi)*x)-t)+sin(b*(y+(c-pi)*x)-t)): Interference angle < 90 adjustable (c)
a*(sin(b*(y-(c-pi)*x)-t)+sin(b*(-y+(c-pi)*x)-t)): Interference angle > 90 adjustable (c)
a*sin(b*(x*x+y*y)-t): Radial wave outward
a*sin(b*(x*x+y*y)+t): Radial wave inward
a*(sin(b*(x^2+y^2)-t)+sin(b*(x^2+y^2)+t)): Standing radial wave
0.4*a*sin(b*(x^2+y^2)-t)/sqrt(0.1+x^2+y^2): Surface wave outward
0.2*a*sin(b*(x^2+y^2)-t)/(0.1+x^2+y^2): Space wave outward