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| what is purpose of stride in arrays? http://forum.alglib.net/viewtopic.php?f=2&t=294 |
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| Author: | umpeikurokawa [ Fri Feb 04, 2011 5:57 pm ] |
| Post subject: | what is purpose of stride in arrays? |
Hello, first of all just like to say that this is a great library. I'm just starting and it is very nice to have this I was trying to use vadd on real_2d_array datatypes and saw that it was not working correctly, but I realized that it was because I was not entering the "strides" as an input and the default stride is 1 when my arrays had strides of 2. what is the purpose of this stride? |
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| Author: | Sergey.Bochkanov [ Fri Feb 04, 2011 8:52 pm ] |
| Post subject: | Re: what is purpose of stride in arrays? |
There are two meanings of "stride". First, stride is used to align array rows on 16-byte boundary. It is necessary for better caching control, for better utilization of SSE2 intrinsics - for better performance, in two words. Second, when we talk about Level 1 BLAS functions, stride is a distance between consecutive elements of vector (row/column). When it is 1, we have vector or row. When you want to work with columns of a matrix, stride is greater than 1. |
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