Some Products and Sums of Sines and Cosines
It is easy to visualize interference patterns using false coloring for height. Some of these playful examples appeared as "Product of three harmonics" [Abstract] in Cliff Pickover's The Pattern Book. Here we use magenta for the highest points and red for the lowest points. The wave patterns we explore are based upon:
c1=cos(x), c2=cos(y), c3=cos(r) 
s1=sin(x), s2=sin(y), s3=sin(r)
where r^2=x^2+y^2
180k
c1 * c2
213k
c1 * c3
206k
c1 * c2 * c3
179k
s1 * s2
214k
s1 * s3
209k
s1 * s2 * s3
171k
c1 + c2
192k
c1 + c3
187k
c1 + c2 + c3
171k
s1 + s2
194k
s1 + s3
177k
s1 + s2 + s3
1423k
Animation changing
from c1 + c2
to c1 + c2 + c3
to c1 + c3 (1.4M)
1338k
Animation changing
from s1 + s2
to s1 + s2 + s3
to s1 + s3 (1.3M)

Scripts and links
· A J script for creating some of these images: v3harm.ijs
· The script requires another J script for creating bitmaps files: raster5.ijs
· Cliff's Home Page
· Cliff's Gallery of Chaos, Fractals and Symmetry