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From: anton@mips.complang.tuwien.ac.at (Anton Ertl)
Newsgroups: comp.lang.forth
Subject: Re: Vector sum
Date: Sat, 19 Jul 2025 14:51:00 GMT
Organization: Institut fuer Computersprachen, Technische Universitaet Wien
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minforth <minforth@gmx.net> writes:
>Am 19.07.2025 um 12:18 schrieb Anton Ertl:
>
>> One way to deal with all that would be to have a long-vector stack and
>> have something like my vector wordset
>> <https://github.com/AntonErtl/vectors>, where the sum of a vector
>> would be a word that is implemented in some lower-level way (e.g.,
>> assembly language); the sum of a vector is actually a planned, but not
>> yet existing feature of this wordset.
>>
>
>Not wanting to sound negative, but who in practice adds up long
>vectors, apart from testing compilers and fp-arithmetic?

Everyone who does dot-products.

>Dot products, on the other hand, are fundamental for many linear
>algebra algorithms, eg. matrix multiplication and AI.

If I add a vector-sum word

df+red ( dfv -- r )
\ r is the sum of the elements of dfv

to the vector wordset, then the dot-product is:

: dot-product ( dfv1 dfv2 -- r )
  df*v df+red ;

Concerning matrix multiplication, while you can use the dot-product
for it, there are many other ways to do it, and some are more
efficient (although, admittedly, I have not used pairwise addition for
these ways).

- anton
-- 
M. Anton Ertl  http://www.complang.tuwien.ac.at/anton/home.html
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