I compute the integral
(y - y1)/((z - z1)^2 + (y - y1)^2))
with respect to y1 (from value -d to d) and to z1 (from value -w to w). As a result I get a reply which inlcludes terms involving the imaginery number i. This should not happen as the above double integral is actually the calculation of the magnetic field around a rectangular wire currying current in the x direction (Bior-Savart law).
Any clues what is going wrong please?
Attachment: biot savart law.nb, URL: ,