Re: Transpose matrix does not work when MatrixForm is used, why?
- To: mathgroup at smc.vnet.net
- Subject: [mg45411] Re: Transpose matrix does not work when MatrixForm is used, why?
- From: Dr Bob <drbob at bigfoot.com>
- Date: Tue, 6 Jan 2004 04:17:29 -0500 (EST)
- References: <001901c3d3c0$c95cf580$6401a8c0@bcolletti>
- Reply-to: drbob at bigfoot.com
- Sender: owner-wri-mathgroup at wolfram.com
This is related to an ongoing thread on computing Transpose (and other
functions) of MatrixForm objects. There should be a better answer, but
here's one in the meantime:
data = Array[{# + Random[], # - Random[]} &, {100}];
z = Regress[data, {1, x, x^2}, x, RegressionReport -> CovarianceMatrix]
X = CovarianceMatrix /. (z /. MatrixForm -> Identity)
X[[2, 2]]
This also works, but NOT when Ted Ersek's suggested fix for MatrixForm is
installed:
X = CovarianceMatrix /. z /. MatrixForm -> Identity
Bobby
"Bruce W. Colletti" <bcolletti at compuserve.com> wrote in message
news:<btb8oi$jp4$1 at smc.vnet.net>...
> Re Mathematica 5.0 running under WinXP Home.
>
> Am using...
>
> z = Regress[...RegressionReport->CovarianceMatrix];
> X = CovarianceMatrix /. z;
>
> ...to extract the given matrix. However, when I use X[[k,k]] to access
> the k'th diagonal element, I get a row instead! The culprit is that
> MatrixForm is the X-head (as FullForm reveals).
>
> How can I strip away this head and make X a list of lists?
>
> Thankx.
>
> Bruce