contour of what ?

[tommy1729]

contour of what ? of the function we are defining with the contour ?

The gradient theorem and residue theorem both show that in many cases the value of a contour integral/line integral is independent of the contour of integration.

So the simple answer to your question is: in many cases, it doesn't matter what the contour of integration is, you get the same result.

gradient theorem and residue theorem are very well known to me.

but andy , i think you got my question wrong.

i didnt ask contour over which ' path ' , i asked over ' what function '.