12:55 AM
I've been writing a little linear algebra library in C. I just got the qr decomposition working! Time to solve some regressions!
Thought I'd share, I'm having fun with it.

12 hours later…
1:13 PM
@MatthewDrury, Nice! Is it this one? Let us know when it's done, it looks cool :)

1:54 PM
Does anyone know what has changed after this question was tagged 'status-completed'?
22

So I just figured out that stack exchange exists like 2 months ago and I am now just getting active in the wonderful world of cross validated and its great. One thing I came across just now is I spent 10 minutes trying to figure out why I could not accept an answer. I was thinking I did not have...

There was a recent question on Meta asking for the vote arrows design to be adapted for color blind folks. That question was merged in the older post above (which had the same idea, but requesting the accepted answer box to be changed). But it seems the vote arrows design did not change, it did?

2:55 PM
@ChrisC Yah, that's me! I wasn't to get through implementing at least glms. I'd also like to learn more about how to make these things efficient. Matrix multiplication, for example, is really nasty to do naively, but there are ways to optimize it:
Because matrix multiplication is such a central operation in many numerical algorithms, much work has been invested in making matrix multiplication algorithms efficient. Applications of matrix multiplication in computational problems are found in many fields including scientific computing and pattern recognition and in seemingly unrelated problems such counting the paths through a graph. Many different algorithms have been designed for multiplying matrices on different types of hardware, including parallel and distributed systems, where the computational work is spread over multiple processors...
By nasty, I mean it interacts really badly with RAM. I'd been wondering how you get around that, seems like that blocking algorithm is the key.
wasn't == want (above).

5 hours later…
8:06 PM
If $x$ is a standard normal vector, which is independent from a matrix $A$, is it true that $x^TAx$ converges to $\text{tr}(A)$?