Magnetic field gradients
Often the gradient of the magnetic induction B is of interest. BiotSavart can calculate and plot components of the magnetic gradient tensor. The naming of these components is best explained by example: the quantity dBxdy is the derivative of Bx with respect to y. Any of these derivatives may be plotted on a linear or planar probe, or used as the quantity of interest in a volumetric probe. These derivatives are also available for use in the macro calculator.
Export of gradient quantities is done by selecting Export gradient... from the File menu when a probe window is foremost.
In general the gradient is calculated using analytic expressions for loops and wire segments, just as the magnetic field. There is no numerical differentiation. Calculation of gradients will be performed using a paraxial expansion when the probe point is within the specified paraxial threshold distance of the axis of a conductor.
