Plotting 3d sphere from equation

I'm looking for a way to plot a 3d sphere given its equation. 
Eg: (x-a)^2 + (y-b)^2 + (z-c)^2 <= R
I found that 'sphere' allows me to plot a unit sphere and that I can change its center using 'surf'. However, I don't see anyway to change the radius. 

I haven't tried 'sphere3d', but from its documentation, it looks like I have to convert my equation to the polar coordinate system.

Is there any other function in matlab that can plot a sphere given an equation like above?

 Thanks,

Answer 1

[Khanh]

Another way I can think of is using 'ellipsoid'. It will be like this:
 [x,y,z] = ellipsoid(a,b,c,R,R,R);
 surf(x,y,z);

Another way, I can do with 'sphere' is to scale the the surface like this:
 [x,y,z] = sphere;
 surf(R*x, R*y, R*z);

Answer 2

[Walter Roberson]

To change the radius of sphere(), multiply all of its coordinates by R (before doing any translation.)

[Khanh]

Thanks Walter. I think that's what I mentioned above with surf(R*x, R*y, R*z), right?

[Walter Roberson]

Yup.