4.2 SCM_VECTORLENGTH

Almost all programs within the ADF package use numerical integration, and this is normally the most time-consuming part of the code. Numerical integration involves summing together results for each 'integration point'. By handling a number of points together you can greatly influence the performance. The number of integration points handled together is called the block length.

If the block length is too small, you will have a significant overhead and the programs will be very slow.

If the block length is too large, lots of data will not fit in cache memory and again the program is not at optimum speed.

The correct block length is somewhere in between, ranging from 32 to 4096 depending on your hardware. Sometimes it pays off to set the block length explicitly NOT to a power of 2 to avoid memory bank conflicts.

Again, try for yourself, with your typical calculation on your production machine to find out the optimal value for your situation. On most machines, 128 is a good compromise value.