Eigen C++ library
Hacker ApprovedThe most recommended of 3 linear algebra libraries
Fast C++ linear algebra library praised for performance and zero-cost abstractions; critics point to slow compiles and large binaries.
Fast C++ linear algebra library praised for performance and zero-cost abstractions; critics point to slow compiles and large binaries.
14 people gave an opinion
- recommend it
- 10
- criticize it
- 4
- approval share
- 71%
Recommended in 7 of 13 months
- November 2025: recommended
- December 2025: recommended
- January 2026: not recommended
- February 2026: not recommended
- March 2026: recommended
- April 2026: recommended
- May 2026: not recommended
- June 2026: recommended
- July 2026: not recommended
- August 2026: recommended
- September 2026: not recommended
- October 2026: recommended
- November 2026: not recommended (month in progress)
Why it carries the badge
- 10 people recommend itNeeds 10 or more, met.
- 2.5 recommenders for every criticNeeds 2 to 1 or better, met.
- Recommended in 7 of 13 monthsNeeds 4 or more, met.
The same three rules apply to every product, and the badge can’t be bought. How the badge works
What people say about it
The reasons people give, with the number of comments that give each one. Open a reason to read what they said.
Why people recommend it
Each mark is one comment
Performance with high-level readability
“You get the readability of high-level code with the performance of low-level code thanks to the "zero-cost abstractions" of Eigen.”
Comment from 25 Nov 2025 in “Python is not a great language for data science” “I use the Eigen matrix library as a replacement for Numpy when I need more performance”
Comment from 18 Dec 2025 in “Learning Fortran (2024)”
What people warn about
Each mark is one comment
Long compile times
“Eigen is one of the worst libraries when it comes to both exe size and compile times.”
Comment from 29 Dec 2025 in “Binaries” “This is also a bit reminiscent of the compile time issues with Eigen”
Comment from 11 Nov 2025 in “Cache-friendly, low-memory Lanczos algorithm in Rust” Large binaries with debug symbols
“Eigen is one of the worst libraries when it comes to both exe size and compile times.”
Comment from 29 Dec 2025 in “Binaries” “I've seen terrible, terrible binary sizes with Eigen + debug symbols”
Comment from 29 Dec 2025 in “Binaries”
Other linear algebra libraries people recommend
The two most recommended other linear algebra libraries, with the same counts for each, so you can compare like for like. The tick on each bar marks the 2 to 1 line the badge needs.
See all 3 linear algebra libraries, rankedWhat people said
13 of the 15 comments that mention it, newest first. Each links to the original comment.
“sensible multidimensional array support even if it isn't built-in”
“Found this gem. A self-hosted, open source alternative to Google Workspace”
“I've also had terrible performance with Eigen when compared to LAPACK. Would not recommend unless you want to spend time profiling performance issues.”
“They use template meta programming to chain linear algebra operations”
“Cool project. Love the clean look.”
“The core engine is now (hopefully) stable enough to be tested.”
“had a better support for pipelines and dataflow oriented programming (at least in the context of what I needed) than Eigen”
“Eigen does have explicit SIMD support for several architectures and SIMD instruction sets.”
“Eigen is one of the worst libraries when it comes to both exe size and compile times.”
“I've seen terrible, terrible binary sizes with Eigen + debug symbols”
“I use the Eigen matrix library as a replacement for Numpy when I need more performance”
“You get the readability of high-level code with the performance of low-level code thanks to the "zero-cost abstractions" of Eigen.”
“This is also a bit reminiscent of the compile time issues with Eigen”
Counts come from 1,795,640 Hacker News comments, November 2025 to November 2026. How we count. Report a mistake.