ABSTRACT
The power series method and the finite difference method both lead to programs which give accurate eigenvalues fairly quickly, without keeping a record of the wavefunction. The eigenvalue differencing approach of §9.4 allows expectation values to be obtained, but this requires a sequence of energy calculations. The author's main interest in microcomputers is centred on their mathematical capabilities, rather than their graphics or networking facilities. The Spectrum Plus, with a new-style keyboard, although in the author's own work the author has found it quite satisfactory to equip the original Spectrum with a DKtronics keyboard when it is to be given repeated use in teaching classes. Although the QL computer is currently the largest one in the Sinclair range, the Spectrum is still very useful for scientific work. The chapter utilizes the BBC computer from time to time in my visiting lectures at various universities and so have tried out several of author's calculations on it.
