[Rcpp-devel] RcppMAtrix<complex> ?

[baptiste auguie]

Thanks for the example, it is useful indeed. However, I am having
difficulties with operations involving whole matrices, rather than
matrix elements. Again I must warn that I don't know C++ ; but the
addition of two matrices does not seem to work out-of-the-box, as well
as more complicated functions. The dispatch of these functions might
not exist for the complex matrix class, or maybe it is not implemented
in Rcpp?

The operations I would need to perform with complex matrices are,

+, -, *, transpose,
as well as operations on 1-column and one-row matrices (== vectors?)
such as exp().

Working component by component is not a very attractive option, so I'm
hoping there is an easy way to define operations between matrices,
matrices and vectors, and matrices and scalars.

Thanks,

baptiste

PS: The problem with my previous email was in the gmail vs. googlemail
domain, as Dirk pointed out (I had had that same problem before, but I
forgot!).

On 22 April 2010 13:17, Romain Francois <romain at r-enthusiasts.com> wrote:
> Thank you for reposting here.
>
> It is not trivial to see what is happening in your example, so I'll just
> give you some tools.
>
> The old api (which the classicRcppMatrixExample example uses) does not have
> support for complex vectors or matrices.
>
> The new api does have support for complex vectors and complex matrices. The
> unit test file runit.ComplexVector.R does indeed contain some very basic
> examples of using ComplexVector, but not complex matrices. However, you can
> use Rcpp::ComplexMatrix.
>
> Here is an example that calculates the sum of the real part of the elements
> of a complex matrix diagonal and the sum of the imaginary part:
>
> require( Rcpp )
> require( inline)
>
> fx <- cfunction( signature( x = "matrix" ), '
>        /* grab the R object as a complex matrix */
>        ComplexMatrix m(x) ;
>        double re_sum = 0.0 ;
>        double im_sum = 0.0 ;
>        for( int i=0; i<m.ncol(); i++){
>                re_sum += m(i,i).r ;
>                im_sum += m(i,i).i ;
>        }
>        return List::create(
>                _["sum real part"] = re_sum,
>                _["sum imag part"] = im_sum
>                ) ;
>
> ', Rcpp = TRUE, includes = "using namespace Rcpp;" )
>
> x <- diag( (1-2i)*1:5 )
> fx( x )
>
> Let us know if this gives you enough to get started.
>
> Romain
>
> Le 22/04/10 12:59, baptiste auguie a écrit :
>>
>> Dear all,
>>
>> I'm hoping to port some R code to C++ to make it faster. The code
>> makes heavy use of matrices of complex numbers, and playing with the
>> RcppExamples package this morning I got the impression that it's not
>> currently implemented in Rcpp. I basically took the example from
>> classicRcppMatrixExample and tried to change the types from double to
>> complex. I must confess that I don't know C++, so maybe I missed
>> something obvious.
>>
>> Attached is my dummy example, as well as the R code I'm trying to port
>> to give you an idea. Any suggestions would be greatly appreciated!
>>
>> Best regards,
>>
>> baptiste
>>
>>
>> PS: This message initially failed to reach the list; in the meantime I
>> got the suggestion from Romain and Dirk to have a look at the class
>> Rcpp::ComplexMatrix and the example in runit.ComplexVector.R
>
>
> --
> Romain Francois
> Professional R Enthusiast
> +33(0) 6 28 91 30 30
> http://romainfrancois.blog.free.fr
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>