# AltiVec

## HOWTO: Using libfreevec using LD_PRELOAD

Submitted by markos on Tue, 19/08/2008 - 14:18

Ok, let's suppose you've downloaded libfreevec, built it successfully and now you want to use it for the whole system, without recompiling the whole system to use the library! Is it possible? Thanks to a glibc feature you can!

There are two ways to do that:

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## Inverse of Matrix 4x4 using partitioning in Altivec

Submitted by markos on Fri, 18/04/2008 - 18:31

We tackle the 4x4 matrix inversion using the matrix partitioning method, as described in the "Numerical Recipes in C" book (2nd ed., though I guess it will be similar in the 3rd edition). Using the AltiVec SIMD unit, we achieve almost 300% increase in performance, making the routine the fastest -at least known to us, matrix inversion method!

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## AltiVec runtime detection in Linux

Submitted by markos on Thu, 10/04/2008 - 15:01

After a little search I did on Google to find how to detect AltiVec runtime in Linux (I used keywords such as runtime altivec detection and similar), I found that there is no single nice article anywhere that describes something so simple. Thankfully, I got a few good answers from benh and dwmw2 in #mklinux/FreeNode, and I decided to put these down in a cleaned up form.

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## Matrix 4x4 Translation of a vector

Submitted by markos on Sat, 01/03/2008 - 20:56

Getting the translation matrix of a vector is essential to do movements of a vector in 3D space.

For the theory behind translation matrices please see [url=http://en.wikipedia.org/wiki/Translation_\(geometry\)]here[/url].

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## Matrix 4x4 Identity matrix

Submitted by markos on Sat, 01/03/2008 - 20:54

The nice thing about the identity matrix, is that we don't have to do any reading of the matrix. And since the form of the identity matrix is already known: