A set of programming techniques which can reduce the time required to develop scientific programs is presented. Subroutines are designed to allow every execution path to be tested independently. Checksums are used to compress arrays and groups of variables without losing meaningful debugging information. Invariance assertions on checksums are used to detect incorrect behavior of a program at a place near the source of the error. Traces of checksums of groups of variables are used to monitor the time evolution of intermediate results. By comparing the checksums produced in tracing the program and the checksums produced in tracing a reference copy of the program, errors can be rapidly localized when a program is modified, ported, put in parallel, or optimized for a particular machine.>

A multiwindow, multimethod device analysis algorithm that combines the advantages of efficient drift-diffusion simulators and accurate physical models using Monte Carlo methods is described. The PISCES 2-D device analysis program is used whenever the drift-diffusion model is valid. In situations where the drift-diffusion model breaks down, a window is opened in the part of the device where the hot-carrier effects are important. The Monte Carlo method in the McPOP program is then applied in the window. The simulation results obtained match well with the measured data and the full Monte Carlo results. The CPU time required has been reduced by a factor of 3 to 10 compared with the full Monte Carlo simulation. A parallel Monte Carlo algorithm has been used in the McPOP program. A 20-processor system speeds up the program by a factor of 18.5.>

Frame predictive vector quantization is developed to compress the bit rate for coding the LPC filter coefficients to under 250 bits/sec. An innovative LPC compression technique, matrix quantization, is also developed to compress the LPC filter coefficients to a rate under 150 bits/sec. Subjective evaluation with the diagnostic rhyme test (DRT) finds the proposed techniques to be feasible for intelligible speech transmission at bit rates between 400 bits/sec and 200 bits/sec.