From: "Bruno Luong" <b.luong@fogale.findmycountry>
Newsgroups: comp.soft-sys.matlab
Subject: Re: funny problem about the precision of matrix transpose and inverse.
Date: Wed, 31 Oct 2012 07:18:12 +0000 (UTC)
Organization: FOGALE nanotech
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"Ha" wrote in message <k6q8kc$8i4$>...

> Backslash seems provide no help.  I still get a warning that the matrix is badly scaled or nearly singular and sometimes it gives rise to NaNs.

Then your system is not invertible, or nearly so. Often because you forget to add appropriate constraints, boundary condition to make the problem well-posed. It might also be badly scaled, as the warning message suggests.

You could try to use pinv(), but the problem might lie well before the system was formed.