How useful is a stride in arrays and matrices?

08022019, 10:14 PM
(This post was last modified: 08022019 10:25 PM by StephenG1CMZ.)
Post: #1




How useful is a stride in arrays and matrices?
I have been looking at software implementing matrix and vector operations, such as BLAS (Basic Linear Algebra Subprograms). Many of these routines include a stride or increment parameter, such that for example SUM([1 2 3],1) returns 6 but (, 2) returns 4 as the sum of the 2 effective elements 1 3..
I can see how using a stride might be useful, for example allowing a vector to contain [x y x y] instead of having two vectors [x x] and [y y]. But also having two separate vectors could be useful too. What I am not so sure of is how popular the use of a stride is in datasets, in particular on calculators, where the smaller Ram and less convenient data entry might encourage smaller nonstrided matrices. On the HP Prime AFAIK there is not an obvious Sigma(vector, stride) syntax, although I am sure that a syntax to implement that exists. But how useful would such functionality be on a calculator? Is there a need? Stephen Lewkowicz (G1CMZ) https://my.numworks.com/python/steveg1cmz 

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