FUNCTIONAL REPRESENTATIONS IN NON-FOURIER BASIS WITH APPLICATIONS

Orthogonal trigonometric basis functions in (-pi,pi) are considered an d the suitability of Fourier-like expansions involving odd harmonics o f the semifundamental frequency is noted. Comparison with the conventi onal representation is made, pointing out the advantages of employing non-Fourier bases. As a practical application, near-exact results of v ariational calculations for the ground state of the quartic-anharmonic -oscillator problem are presented both for small and large coupling st rengths.