Eval Command
This command numerically evaluates and displays the results of calculator operations such as integrations, maximum or minimum field computations, field values at points, and so forth. The quantity to be evaluated must be in the top register. The Eval command computes the numerical results of the operation, which replace the contents of the register.
For instance, to find the current around a loop, you must numerically evaluate the following integral for that loop:
Because H and I are complex quantities, you first need to evaluate the real part of H to obtain the real part of I, then evaluate the imaginary part of H to obtain the imaginary part of I. To do this:
- Load H into the calculator using the Qty command.
- Take the real part of H using the Cmplex/Real command.
- Load the rectangular loop using the Geom/Line command. Create the loop, a closed polyline, to integrate over.
- Click Tangent to get the component of H along the line.
- Take the integral around the loop using the ∫ command.
- Click Eval to evaluate the integral. The real part of I appears in the top register.
- Repeat this process using the imaginary part of H (found with the Complex/Imag command) to obtain the imaginary part of I.