GEMM Tutorial and UlmBLAS
Comments on “GEMM Tutorial and UlmBLAS”
3 judges. Scored by all three judges. Only the day’s top stories get the claim check. How far stories are checked
Michael Lehn's GEMM tutorial, originally written in 2014 and now hosted on GitHub, walks through building a fast matrix multiplication without Strassen-style algorithms. Instead it relies on cache-aware blocking, copying matrix blocks into buffers, and SIMD register instructions, step by step from a naive triple loop.
Why it ranked
No. 108 of 111 with a score of 0.55. The panel rated it highest on new information (0.87) and technical depth (0.74), lowest on significance (0.45). The judges disagreed most on reader interest (spread 0.43), so the story is marked contested. Placed No. 108, No. 109 by score alone: the 20th Programming & dev tools story of the day (−0.080). The placement terms move stories; they are not part of the score.
- AI judgeJudge 2claude-haiku-5-5
- A practical, technically deep tutorial on cache-blocked GEMM and SIMD with a BLAS implementation and CUDA work. Old 2014 material with a new repo link; modest broad significance, substantiated by working code but mostly narrative.}
- AI judgeJudge 3gpt-5.6-luna
- A practical, technically substantive tutorial on cache blocking, SIMD, BLAS implementation, and CUDA performance, backed by code. Important to systems and numerical-computing practitioners, though narrower than general software engineering.
Each judge wrote its line after answering the rubric, with the site and the author still hidden. Every answer behind this is in the table under Score.
Score
0.55total under rubric v2.3Contestedjudges differ by 0.43 on reader interest
- Significance0.45
- Reader interest0.54
- Audience breadth0.50
- Practical relevance0.70
- Substantiated0.63
- Technical depth0.74
- New information0.87
- Counts against: Promotional0.06
- Counts against: Overclaim0.14
Each judge’s answer per question (0–1), their mean and spread, and what the question adds to the score (weight × mean).
| Question | Judge 1 | Judge 2 | Judge 3 | Mean | Spread | Weight | Contribution (weight times mean) |
|---|---|---|---|---|---|---|---|
| SignificanceHow much does this change what people in tech know or can do? | 0.45 | 0.40 | 0.50 | 0.45 | 0.10 | +0.24 | +0.108 |
| Reader interestWould a well-informed senior engineer or tech founder want to read this today, and likely pass it on? | 0.29 | 0.62 | 0.72 | 0.54 | 0.43 , above the contested threshold | +0.26 | +0.141 |
| Audience breadthHow many people who build technology does it concern? | 0.56 | 0.40 | 0.55 | 0.50 | 0.16 | +0.13 | +0.065 |
| Practical relevanceHow useful is it to someone who builds software or tech products? | 0.55 | 0.72 | 0.82 | 0.70 | 0.27 | +0.22 | +0.153 |
| SubstantiatedHow well is it backed? Consider whether it is the primary source, and whether its main claims come with data, code, a demo, a reproducible method or citations. | 0.51 | 0.60 | 0.78 | 0.63 | 0.27 | +0.05 | +0.031 |
| Technical depthHow technically substantive is it? | 0.66 | 0.78 | 0.78 | 0.74 | 0.13 | +0.05 | +0.037 |
| New informationDoes it contain information absent from the stories covered in the last 7 days (list provided)? | 0.90 | 0.90 | 0.82 | 0.87 | 0.08 | +0.05 | +0.044 |
| PromotionalIs it mainly marketing with little substance (a press release, ad or sponsored post with no real information)? A launch post that carries real news is not promotional. | 0.11 | 0.05 | 0.03 | 0.06 | 0.08 | −0.19 | −0.012 |
| OverclaimDo the headline or conclusions claim more than the body supports? | 0.19 | 0.15 | 0.08 | 0.14 | 0.11 | −0.11 | −0.015 |
| Sum of contributions | +0.552 | ||||||
| Claim-check penalty | 0.000 | ||||||
| Total, as published | 0.552 | ||||||
Spread is the highest minus the lowest judge answer. marks a spread above 0.40: the judges disagree, and the story is marked contested.
The badge for this ranking, for the author's page or anyone's: one line of HTML, and it links back here.
<a href="https://rubric.hrih.si/editions/2026-10-31/108/"><img src="https://rubric.hrih.si/badge/2026-10-31/108.svg" alt="Ranked #108 on Rubric, 31 Oct 2026" width="252" height="28"></a>Also covered by
No other coverage was clustered with this story.
Elsewhere
Elsewhere: HN 3 pts, not on front page
Recorded for context only, checked 31 Oct 2026, 05:46 UTC. It played no part in the ranking.