| Re: [eigen] inf-norm of complex-matrix columns |
[ Thread Index |
Date Index
| More lists.tuxfamily.org/eigen Archives
]
- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] inf-norm of complex-matrix columns
- From: Benoit Jacob <jacob.benoit.1@xxxxxxxxx>
- Date: Thu, 3 Jun 2010 16:35:39 -0400
- Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type :content-transfer-encoding; bh=0fJUKatF90m+TCEpjWnLscGbWBCAiHQoYIqNNvd2aRE=; b=f+GRJDyCdVpCNKNPzDpCkZpsqO4wt7UwidX/L2ubhlukEQMg5hr4zk9Zz/tyxkjLsX QL110vn2khe172QOpT41lwsOjHho8wEiA16mSWwg2ALbizwSnyk1PqfcAxfVGbsEgoco opexqk7tIzx9Jq4zmQo0vxWgeA4a7SyLQvYh8=
- Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; b=jKV3qUWUrSw7SkLn4OgH0njd8fannHtJW+REIGxySpMjOK/In+tnAu1nTSNDXm+bI4 dTXckkx838a3yuS+UmD07uU1av9pjdEXOgrj3B58YAiL9Rx63cfCRGWcfZ64m2TmiScW DaBL0hxjTY+9HEfW8yT3/13Q57DLF+IszjrCw=
Yep, and also, IIRC, we have a built-in function for that:
matrix.lpNorm<Infinity>()
Benoit
2010/6/3 Martin Senst <martin.senst@xxxxxx>:
> Hi,
>
> I think either
>
> M.cwise().abs().colwise().maxCoeff();
>
> or
>
> M.cwise().abs2().colwise().maxCoeff().cwise().sqrt();
>
> is what you want. With complex numbers, the latter version is probably faster
> since it computes fewer square roots.
>
> Martin
>
>
>
>
>
> Am Donnerstag 03 Juni 2010, 21:21:38 schrieb Manoj Rajagopalan:
>> Hi,
>>
>> Can someone help me come up with an expression to calculate the
>> infinity-norm of the columns of a matrix, treated as vectors? I want to
>> calculate the modulus of the complex entries in each column, and the
>> maximum within that column. Therefore, my result should be a
>> vector-expression whose length is the number of rows. In the following
>> case, 4.
>>
>> MatrixXcd M(5,4);
>> M.setRandom();
>> M.colwise().?????
>>
>> Thanks,
>> Manoj
>
>
>
>