21. Traditionally, harmonic functions are associated with the real and imaginary parts of an analytic function. 22. It is an Eisenstein prime with no imaginary part and real part of the form. 23. The real part is the velocity potential and the imaginary part is the stream function. 24. A real number can be regarded as a complex number whose imaginary part is 0. 25. If a non-zero solution is desired, the imaginary part of the eigenvalue cannot change positive. 26. The idea is for the sum to be 13, the imaginary part must be 0. 27. The imaginary part of f ( x ) would just be mapped on the z axis. 28. More generally, the imaginary parts of the eigenvalues of the anisotropic dielectric tensor should be considered. 29. Say S ^ { IJ } is self-dual, write it as a real and imaginary part , 30. In a passive metamaterial medium this determines a negative real and imaginary part of the refractive index.
