Noise reduction in Matlab arrays

Question

I used median filtering in Matlab to reduce noise in arrays. I was calculating the velocity and acceleration of an object. The velocity part worked fine, and the result I got was exactly what I expected.

I stumbled in to problems regarding the acceleration. I noticed the acceleration was not behaving well; I noticed rectangular shapes instead of the expected smooth shapes.

The plot for acceleration should be a sinusoidal wave for cam and follower in an engine but the problem is that the edges of the wave are not smooth but in form of straight lines.

For velocity I used vavg=medfilt2(v, [1 5])

For accel I used aavg=medfilt2(a, [1 5 ])

Is there any other filter that I should use to get accurate edges?

Are there other filter functions that could be useful?