ResidueSum
ResidueSum[f, z] finds the sum of residues of the meromorphic function f with the variable z.
ResidueSum[{f, cons}, z]finds the sum of residues of f within the solution set of the constraints cons.
Examples
Sum of all residues:
ResidueSum[1/(z^2 - 1), z]
(* 0 *)With constraints:
ResidueSum[{1/z, Im[z] > 0}, z]For a rational function:
ResidueSum[1/((z - 1)(z - 2)), z]Please visit the official Wolfram Language Reference for more details.