The vectorization of ITPACK 2C

ITPACK 2C 14 is a package of seven iterative algorithms for solving sparse linear systems represented by Au = b , where A is symmetric and positive definite or mildly non‐symmetric. This paper describes the techniques used to vectorize the iterative algorithms in the ITPACK 2C package for the Cyber 205 and Cray X‐MP vector computers. The resulting package was named ITPACKV 2C. 15 The basic iterative methods in ITPACK 2C are described in terms of matrix–vector multiplications and forward and backward solutions, and the techniques used in the vectorization of these and other computational kernels are given. Results of experiments using ITPACK 2C and ITPACKV 2C are given, including a comparison of megaflop rates and timings for two model problems.