Convex Computer the C-series vector computer, the Exemplar was a parallel-computing machine that used HP PA-7200 microprocessors, connected together using SCI. First dubbed MPP, these machines were later called SPP and Exemplar and sold under the SPP-1600 moniker. The expectation was that a software programming model for parallel computing could draw in customers. But the type of customers Convex attracted believed in Fortran and brute force rather than sophisticated technology. The operating system also had terrible performance problems which could not easily be fixed. Eventually, Convex established a working partnership with HP's hardware and software divisions. Initially it was intended that the
Luneburg lens one side, and formula_14 only on the other: The parameter formula_19 is a constant for any given ray, but differs between rays passing at different distances from the centre of the lens. For rays passing through the centre, it is zero. In some special cases, such as for Maxwell's fish-eye, this first order equation can be further integrated to give a formula for formula_14 as a function or formula_13. In general it provides the relative rates of change of formula_14 and formula_13, which may be integrated numerically to follow the path of the ray through the lens. Luneburg lens A