To re-produce the bug:
just fill 2 columns, say A, B with Col(A)=0 to 360, and col(B)=sin(col(A)), plot col(B) then choose Analysis->Calcalus->Diff,
The result is a cosine-like curve, however, the maximum is reduced to around 0.02 not the value it should be (should be 1).

However, if you fill the second column with col(A)^2, you can get the right result.

I think it should be the SRs, when apply those SRs, it changed some function relating to differentiation accidentally.

Hope someone can fix this problem as soon as possible, as there could be other functions cannot be correctly derived.

Tantiger and ru_pro

In response to your interest in how our differentiation feature works, a Knowledge Base item has been prepared. Please take a look at it since it should clear up any confusion. If you would like to link to it directly, please click here. I think you will find that the explanation proves the bug was actually in 6.0 release and not SR1. I also think you will find that using radians is not a "quick fix", but rather the correct angular unit to use if you expect the differentiation to yield "theoretical" results.

Sincerely,
Ryan Toomey