# Matmul for large (“tall”) data

**URL:** <https://discourse.julialang.org/t/matmul-for-large-tall-data/139818>\
**Category:** New to Julia\
**Tags:** question\
**Created:** [October 4, 2026, 6:37pm UTC](https://discourse.julialang.org/t/matmul-for-large-tall-data/139818 "2026-10-04T18:37:09Z")\
**Posts on this page:** 1\
**Page:** 2

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**Author:** ![Oscar\_Smith](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oscar_smith/32/25343_2.png) [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)\
**Post date:** [October 14, 2026, 6:58pm UTC](https://discourse.julialang.org/t/matmul-for-large-tall-data/139818/21 "2026-10-14T18:58:52Z")

</div>

This is `diagv = true*diagv + true*X*Xi'` (using `true==1`)

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