Maybe consider improving the Hermite function basis.
See page 66 in Boyd where he writes:
The simplest definition of Hermite functions (integer coef- ficients) unfortunately leads to normalization factors which grow wildly with n, so it is quite helpful to use orthonormalized Hermite functions. (“Wildly” is not an exaggeration; I have sometimes had overflow problems with unnormalized Hermite functions!) From a theoretical standpoint, it does not matter in the least whether the basis is orthonormal or not so long as one is consistent.
Maybe consider improving the Hermite function basis.
See page 66 in Boyd where he writes:
The simplest definition of Hermite functions (integer coef- ficients) unfortunately leads to normalization factors which grow wildly with n, so it is quite helpful to use orthonormalized Hermite functions. (“Wildly” is not an exaggeration; I have sometimes had overflow problems with unnormalized Hermite functions!) From a theoretical standpoint, it does not matter in the least whether the basis is orthonormal or not so long as one is consistent.