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## Re: MEX/Mkoctfile questions about matrices algorithms...why slower?

**From**: |
Quentin Spencer |

**Subject**: |
Re: MEX/Mkoctfile questions about matrices algorithms...why slower? |

**Date**: |
Tue, 14 Nov 2006 16:50:58 -0600 |

**User-agent**: |
Thunderbird 1.5.0.8 (X11/20061107) |

钟 伟生 wrote:
>* I am trying to use the interface functions between MATLAB/OCTAVE and C*
>* to compute the matrices algorithms( like matrix-matrix multiplication*
>* and additon, matrix-vector multiplication ), such as MEX and*
>* DEFUN_DLD. However, after having compared with Matlab, I found the*
>* implemented with C/C++ are not faster than the same on in Matlab,*
>* moreover, it costs more about 30% time. I compared them both in big*
>* and small matrices multiplications.*
>* The results are the same as before.*
>
>* Are there good and bad ways of implementing matrix multiplication*
>* combining MATLAB/OCTAVE and C?*
>
>* Thank you very much!*
Both Octave and Matlab link to external libraries to perform their
matrix and vector computations, and those libraries are already highly
optimized and probably faster than anything you could using a simple Mex
file. If you want faster matrix math, the ATLAS project has made this an
area of ongoing research. If you are not already using ATLAS libraries
with octave, I suggest downloading them and learning how to optimize
them for your computer.
Quentin