How to draw a circle onimage data matirx (containing linear indices to colormap)

I have written the following code to do the operation but it doesn't seem to be working????

figure
M = 64 * ones (100,100)
image (M)
o = 0:0.1:2*pi;
r = 30;
M(50,50)=32;
M(int8(50+r*cos(o)),int8(50+r*sin(o)))=0;
M(50,50)=32;

image(M)

Answer 1

[Sean de Wolski]

FAQ:How to make a Circle?

[simar]

Thanks for help. But if you have time could you please explain ehy my method is not mathematically stable to generate a circle??

I'm still wondering ???

[Sean de Wolski]

If you run each of these commands separately:

int8(50+r*cos(o))

int8(50+r*sin(o))

You'll see they each create a vector. Thus the matric is going to create the equivalent of meshgrid(v1,v2) out of these two vectors. That's why you see the mesh shape in your image.