Re: Dynamic mutidimensional arrays

[Fischlin Andreas]

See below

On Wed, 05.04.23, at 11:00, Benjamin Kowarsch <trijezdci@gmail.com> wrote:

Hi

On Wed, 5 Apr 2023 at 17:46, Fischlin Andreas <andreas.fischlin@env.ethz.ch> wrote:

Have you actually looked at LgMatrices? There is no such run time penalty from calling a procedure such as value(M, i,j). You simply write e.g.

     val := A^[i]^[k] * B^[k]^[j];

But that will lead to unnecessary cache misses because of multiple levels of indirection.

Indeed, I overlooked that point.

If you have such an _expression_ deeply nested in a loop, these cache misses will add up and significantly impact performance.

It is better to allocate all metadata (such as length of a vector) and payload data together in a single memory block. This is called data locality.

regards

benjamin

Cheers,

Andreas

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