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POAccessing a subslice of a boost matrix in a helper class
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  1. POAccessing a subslice of a boost matrix in a helper class
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    copied!<p>I'm trying to build a class that eases the use of the boost boost::numeric::ublas::matrix. Thus I've got:</p> <pre><code>using namespace boost::numeric::ublas; typedef matrix&lt;double&gt; matrix_t; class Tensor : public matrix_t { public: Tensor (const int M, const int N) : matrix_t(M, N) { } virtual ~Tensor() { } Tensor SubMatrix (const int start1, const int size1, const int start2, const int size2) const; void Print() const; }; // tensor </code></pre> <p>And I further define the <code>SubMatrix()</code> as follows:</p> <pre><code>Tensor Tensor::SubMatrix (const int start1, const int size1, const int start2, const int size2) const { matrix_slice&lt;matrix_t&gt; s (this, slice(start1, 1, size1), slice(start2, 1, size2)); Tensor t (matrix_expression&lt;matrix_t&gt; (s)); return t; } </code></pre> <p>I'd like to be able to easily create new <code>Tensor</code>s by grabbing sub-matrices from within a <code>Tensor</code>. The compiler is complaining with the following:</p> <pre><code>g++ -ftemplate-depth-100 -Drestrict= -Wall -Wno-deprecated -g3 -ggdb -Wall -D_GLIBCXX_DEBUG -I/home/eshamay/md/src -I/home/eshamay/share/include -I/usr/include -I/usr/local/include -I/home/eshamay/src/boost-1_43_0 -L/home/eshamay/share/lib -L/home/eshamay/src/lapack-3.2.1 -lconfig++ -c -o morita2002.o morita2002.cpp morita2002.cpp: In member function ‘morita::math::Tensor morita::math::Tensor::SubMatrix(int, int, int, int) const’: morita2002.cpp:109: error: no matching function for call to ‘boost::numeric::ublas::matrix_slice&lt;boost::numeric::ublas::matrix&lt;double, boost::numeric::ublas:: basic_row_major&lt;long unsigned int, long int&gt;, boost::numeric::ublas::unbounded_array&lt;double, std::allocator&lt;double&gt; &gt; &gt; &gt;::matrix_slice(const morita::math::Tensor* const, boost::numeric::ublas::slice, boost::numeric::ublas::slice)’ /usr/include/boost/numeric/ublas/matrix_proxy.hpp:3192: note: candidates are: boost::numeric::ublas::matrix_slice&lt;E&gt;::matrix_slice(const typename boost::mpl:: if_&lt;boost::is_const&lt;T&gt;, typename M::const_closure_type, typename M::closure_type&gt;::type&amp;, const boost::numeric::ublas::basic_slice&lt;typename A::size_type, typename A:: difference_type&gt;&amp;, const boost::numeric::ublas::basic_slice&lt;typename A::size_type, typename A::difference_type&gt;&amp;, int) [with M = boost::numeric::ublas::matrix&lt;double, boost::numeric::ublas::basic_row_major&lt;long unsigned int, long int&gt;, boost::numeric::ublas::unbounded_array&lt;double, std::allocator&lt;double&gt; &gt; &gt;] /usr/include/boost/numeric/ublas/matrix_proxy.hpp:3183: note: boost::numeric::ublas::matrix_slice&lt;E&gt;::matrix_slice(M&amp;, const boost::numeric::ublas:: basic_slice&lt;typename A::size_type, typename A::difference_type&gt;&amp;, const boost::numeric::ublas::basic_slice&lt;typename A::size_type, typename A::difference_type&gt;&amp;) [with M = boost::numeric::ublas::matrix&lt;double, boost::numeric::ublas::basic_row_major&lt;long unsigned int, long int&gt;, boost::numeric::ublas::unbounded_array&lt;double, std:: allocator&lt;double&gt; &gt; &gt;] /usr/include/boost/numeric/ublas/matrix_proxy.hpp:3155: note: boost::numeric::ublas::matrix_slice&lt;boost::numeric::ublas::matrix&lt;double, boost::numeric::ublas::basic_row_major&lt;long unsigned int, long int&gt;, boost::numeric::ublas::unbounded_array&lt;double, std::allocator&lt;double&gt; &gt; &gt; &gt;::matrix_slice(const boost::numeric::ublas::matrix_slice&lt;boost::numeric::ublas::matrix&lt;double, boost::numeric::ublas::basic_row_major&lt;long unsigned int, long int&gt;, boost::numeric::ublas::unbounded_array&lt;double, std::allocator&lt;double&gt; &gt; &gt; &gt;&amp;) morita2002.cpp:112: error: conversion from ‘morita::math::Tensor (*)(boost::numeric::ublas::matrix_expression&lt;boost::numeric::ublas::matrix&lt;double, boost::numeric:: ublas::basic_row_major&lt;long unsigned int, long int&gt;, boost::numeric::ublas::unbounded_array&lt;double, std::allocator&lt;double&gt; &gt; &gt; &gt;)’ to non-scalar type ‘morita::math:: Tensor’ requested </code></pre> <p>After attempting a number of variations to appease the compiler, I'm stumped. What's the issue, and why can't I just create the matrix_slice the way it's written?</p>
 

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