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Matrix Rank

• To: mathgroup at smc.vnet.net
• Subject: [mg7604] Matrix Rank
• From: gah <gah at math.umd.edu>
• Date: Thu, 19 Jun 1997 15:53:21 -0400 (EDT)
• Organization: University of Maryland, College Park
• Sender: owner-wri-mathgroup at wolfram.com

V. Nandagopal wrote:
> 
> Hello,
> 
>         Is there any function which will give me the rank of a matrix A?
> Something of the form Rank[A]?
> 
>         Thanks in advance,
> 
>         V. Nandagopal
>         School of Mathematics
>         Tata Institute of Fundamental Research
>         Colaba, Bombay 400 005, India
> 
>         e-mail: nandgopa at math.tifr.res.in


1) Count the number of nonzero rows in RowReduce[A]. This is safe only
with infinite precision (no decimal points).
2) If the matrix is numeric (decimal points) try SingularValues[A]. The
number of singular values returned is Mathematica's default estimate of
the rank. You can change the estimation criterion via the Tolerance
option.

--Garry Helzer
(gah at math.umd.edu)