Hello everybody, My question to you is how can I compute the values of Hr and Hz given the value of A - the magnetic vector potential. The reason I seek this: I'm using the FEMM software to obtain the H values at points around a solenoid. The .ans file that FEMM creates has a huge list of numbers which I found to be the magnetic potential. FEMM manages to retrieve the values of Hr and Hz from this list of Magnetic potential values. Here's a sample of the .ans file: ... [Solution] 2941 1.2085532825853653 4.0843637420137959 -3.9469544215389256e-005 1.1273460445780257 4.3874332801995255 -7.8792243048921603e-006 1.3411542731880106 3.7999999999999998 -7.0806330952824349e-005 1.4562831499937583 4.2684393799265425 -3.0708797381233563e-005 1.1000000000000001 4.7000000000000002 2.6544667022034454e-005 1.4823341543420145 4.5759703098370341 8.5327589548402048e-006 1.52112000238584 3.5429823025642291 -9.6872108040739851e-005 ... The first column is the r value, the second the z value and the third is our A. I need to compute Hr and Hz (or Hx and Hy in the planar case) so that I can use Matlab directly on the .ans file that FEMM creates. Seems simple enough, but how do I do this? Can somebody point me to the formula, OR if you know FEMM well, can you explain the .ans file for me? Thanks, -rsr_life.