| Re: [eigen] initializing a matrix so that all columns are copies of one column |
[ Thread Index |
Date Index
| More lists.tuxfamily.org/eigen Archives
]
- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] initializing a matrix so that all columns are copies of one column
- From: Douglas Bates <bates@xxxxxxxxxxxxx>
- Date: Sat, 10 Dec 2011 09:38:41 -0600
- Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type :content-transfer-encoding; bh=9BUsnSLL9o/On/8OSDe3FpHH9LVMeV57B9oEn7xYakc=; b=p7ZsRBXR0VjtyuOYXYDiEP1zLreyz98//GFU6uJEHCor7qQq5L0GIuR8CFJmhNggb4 1ZaG8a9AZW7VESYQKJ47GLjamqeULw+3gPxoUZcLKN4MgPZCVQ7j9RdsEt/JomtKkEZ0 tDTrUx/B1fCOACBq3x/j4bOO8tSc7YLkIc7TQ=
On Fri, Dec 9, 2011 at 4:15 PM, Gael Guennebaud
<gael.guennebaud@xxxxxxxxx> wrote:
> here you go:
>
> VectorXd maxdev(pts.colwise() - c).array().abs().rowwise().maxCoeff();
>
> You can also use replicate(...) to form an expression of cmat (see the
> documentation of replicate).
Thank you.
> On Fri, Dec 9, 2011 at 10:41 PM, Douglas Bates <bates@xxxxxxxxxxxxx> wrote:
>> In an optimization algorithm I have an n by n+1 matrix whose columns
>> correspond to parameter vectors. At one point I want to subtract a
>> given n vector from each column, convert to absolute values, and find
>> the maximum coefficient in each row. The matrix is called pts and the
>> position I want to subtract is a centroid called c. If I can think of
>> a way of creating another n by n+1 matrix whose columns are copies of
>> c, let's call it cmat, then I can write
>>
>> VectorXd maxdev( (pts - cmat).array().abs().rowwise().maxCoeff() );
>>
>> but the best I have been able to come up with for constructing cmat is
>>
>> MatrixXd cmat(n, n+1);
>> for (int i = 0; i <= n; ++i) cmat.col(i) = c;
>>
>> Is there a more elegant way of doing this?
>>
>>
>
>