[R] problem with outer and image

Bill Simpson wsi at gcal.ac.uk
Tue Oct 5 13:58:12 CEST 1999


I want to make a picture of a cos wave grating (pattern of fuzzy stripes).
First I try to make a plot of a cos wave:
x<-seq(1:100)
y<- 10*cos(2*pi*x*3/length(x)+0)+300
plot(x,y)
That works fine. 3 cycles of cos wave. Now try for grating.

time<-seq(1:100)
f<-function(x,time) 10*cos(2*pi*x*3/length(x)+0)+300
z<-outer(x,time,f)
image(x,time,z)
I get a vertical grating as expected, BUT now I get <1 cycle of cos
wave. Varying the frequency (3 above) does nothing. I don't understand
what I am doing wrong.

Thanks very much for any help.

Bill

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