Hi,(adsbygoogle = window.adsbygoogle || []).push({});

Given an over-determined system of linear equationsy=A c, the condition number of matrix A essentially says how good vector c can be restored from measurements y.

Changing the order of rows clearly does not change the condition number.

But is there information/literature on how to best choose a subset of rows to improve the condition number?

Say, e.g., vector c is small (30) but a large number of measurements are available (>>1000) and the goal is to reduce the number of measurements as much as possible (e.g. I only want to use 50 measurements). From experiments I find I get best results when just picking a random set of 50 rows. But is this really the case? Is there a way to proof this/understand this?

Given the fact I know the structure of the matrix A, is there a chance to find an optimal selection of rows?

Thanks

divB

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Row selection of matrix and the condition number

Loading...

Similar Threads for selection matrix condition |
---|

I Eigenproblem for non-normal matrix |

A Eigenvalues and matrix entries |

A Badly Scaled Problem |

I Adding a matrix and a scalar. |

**Physics Forums | Science Articles, Homework Help, Discussion**