In EM.Ferma, you can define a path integral along a line segment that is parallel to one of the three principal axes, or a loop integral on a rectangle that is parallel to one of the principal planes. You can also define flux planes or flux boxes. All this is done from the same Field Integral Dialog. To define a Field Integral, right-click on "Field Integrals" in the Navigation Tree and select "Insert New Observable..." from the contextual menu. The Integral Type drop-down list gives five options:
<ol>{| class="wikitable"<li>|-! scope="col"| Field Integral Type! scope="col"| Output Data File(s)|-! scope="row"| Voltage Path</li><li>| voltage.DAT|-! scope="row"| Current Loop</li><li>| current.DAT|-! scope="row"| Flux Plane</li><li>| flux_H.DAT|-! scope="row"| Flux Box</li><li>| flux_E.DAT|-! scope="row"| Energy Box</li></ol> | energy_E.DAT & energy_H.DAT|}Â
The domain of the field integral is set using the "Integration Box Coordinates" section of the Field Integral dialog. Box domains are specified by the coordinates of two opposite corners. Voltage Path requires a line; therefore, two of the coordinates of the two corners must be identical. Otherwise, an error message will pop up. For example, (0, 0, 0) for Corner 1 and (10, 0, 0) for Corner 2 define a Z-directed line segment. Current Loop requires a rectangle; therefore, one of the coordinates of the two corners must be identical. For example, (0, 0, 0) for Corner 1 and (10, 10, 0) for Corner 2 define a rectangle in the XY plane.