Mie Scattering Calculations: Advances in Technique and Fast, Vector-speed Computer Codes

Dave published the first widely-used Mie scattering programs in 1968. Even on the fastest computers, these programs and their descendants often took a great deal of computer time for problems of practical interest. In the intervening years, there have been a number of improvements in technique (some developed by this author and reported herein for the first time). At the same time, vector processing has increasingly become the wave of the future in scientific computing machines, and Mie computations can be effectively reorganized to take advantage of it. The present document gathers these improvements in technique, together with the necessary reorganization to attain vector speed, to produce a new Mie scattering program suitable for modern computation. This program, MIEV0, attains as much vector speed as possible within the constraint of using the minimum possible memory. MIEV0 is suitable for almost any computer, whether or not it has vector capabilities, and is generally faster and better designed than existing Mie programs. Detailed timing results are presented for MIEV0. The program is thoroughly tested and documented and is exceptionally reliable and well-conditioned. Mie results up to size parameters of 20,000 have been generated without difficulty. Wiscombe/NCAR Mie report 7