Re: [ublas] define a matrix in my class

Subject: Re: [ublas] define a matrix in my class
From: David Bellot (david.bellot_at_[hidden])
Date: 2010-02-02 09:05:59

It's a nice solution.
Anybody correct me if I'm wrong. In Gianluigi's solution, a myclass
instanciation, a first identity_matrix object is created.
Then in it's constructor, a second one is created, then a copy constructor
is called.
Now if you pass initialization parameters into the constructor
initialization list like
myclass::myclas() : qt(3), you will only have one constructor called for qt
and no copy-constructor.

I think it doesn't matter if instanciate that one time, but if myclass is
instanciated a huge number of time, the overhead can be quite desastreous ?

Am I right or wrong ?

Cheers,
David

On Tue, Feb 2, 2010 at 15:00, Gianluigi Caddeo <ggigi78_at_[hidden]> wrote:

> hi
>
> I solved in this manner:
>
>     ublas::identity_matrix<double> qt;   // declaration
>
> qt=identity_matrix<double> (3);  // initialization
>
> thanks
>
> gigi
>
>
> On Mon, Feb 1, 2010 at 7:00 PM, Gianluigi Caddeo <ggigi78_at_[hidden]>wrote:
>
>> hi
>>
>> I try to define a matrix in my class but
>> I'have every time this problem:
>>
>> myclass.h:53: error: expected identifier before numeric constant
>> myclass.h:53: error: expected ‘,’ or ‘...’ before numeric constant
>>
>> the code is like this:
>>
>> #include <boost/numeric/ublas/blas.hpp>
>> #include <boost/numeric/ublas/matrix.hpp>
>>
>> namespace ublas = boost::numeric::ublas;
>>
>> class myclass {
>>
>> public:
>>
>>     ublas::identity_matrix<double> qt(3);
>>
>> };
>>
>>
>> where is the problem? please help me...
>>
>>
>> thanks you
>>
>> gigi
>>
>
>
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-- 
David Bellot, PhD
david.bellot_at_[hidden]
http://david.bellot.free.fr