Floating point computation rates

The maximum vector capability occurs for matrix multiplication, for which the measured time on the CRAY-1 is twenty times faster than the best hand coded routines on the CDC 7600 or IBM 360/195. The maximum rate is circa. 135 Mflops (Millions of floating-point operations per second) for matrices that have dimensions which are a multiple of 64, the vector register size. The rate of computation for matrix multiplication is shown in figure 1 as a function of matrix size. 

The branch for the case when the squared pair separation is outside the table will inhibit vectorization. The last element of the table has been changed to zero and all occurrence outside the table are truncated to LMAX. The rest of the code, which is not executed on the VAX or CDC 7600, is executed here. It is often necessary on a vector machine to increase the total number of floating point operations to achieve vector rather than scalar processing. The MFLOP rates reported here are computed on the basis of the original number of floating point operations. The extra ones added to achieve vectorization are not included. 

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