| Re: [eigen] Qt's container support |
[ Thread Index |
Date Index
| More lists.tuxfamily.org/eigen Archives
]
- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] Qt's container support
- From: "Benoit Jacob" <jacob.benoit.1@xxxxxxxxx>
- Date: Tue, 20 Jan 2009 17:03:02 +0100
- Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:in-reply-to:mime-version:content-type :content-transfer-encoding:content-disposition:references; bh=RHmJ24Wv0pEPKb63s8obLfTzZXAhsrLsEgfP6uVu5xQ=; b=khdUxoS+j4rrnCeW4QhFfetCmd9/mXhRkgygODPT3Q0RtLzn/Bdj0DVV9jkqB7ID6Y +HG2nkOmVoeFlnxpjeaGZglszNgehaJmidRftKosW3YWXwyOkW5/nsiOxi+AN1XzPOrL x3zYtBnIRDLP3yO9Up2gitywZRJyXDq0qb4KY=
- Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=WFSMTS7BXalepxAZY8CuvuJz2QvMkITnMruR82GTMOpUuy0BcMngVBZ1GdFQLzIvf6 mpgW10kyhpBDVHa2F9VHxHL4ZN5hGj6w+6//Fd6Wp8LkwZSD1ICPxLDiQgc0YL7lNBmx ZXiDhiRF0IEt3crQT0jemvtfMI5D+7xyBbCnA=
2009/1/20 Keir Mierle <mierle@xxxxxxxxx>:
> What is wrong with (a)? I'd like to have this anyway.
In my understanding the main problem with (a) was that it would
require operator= to start with an if() to check if the matrix is
already initialized (so runtime overhead).
Perhaps this argument isn't convincing: dynamic-size matrices involve
runtime branching anyway eveytime you have to loop over their
coefficients, so this if() is going to be negligible.
It's true that this aspect of our API is one of the things that's
causing the most trouble to users. I'm open to reconsidering it. But
first: is there another reason for the current behavior that i
forgot...?
Benoit