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Questions tagged [boost-ublas]

A Boost C++ library directed towards scientific computing on the level of basic linear algebra constructions with matrices and vectors and their corresponding abstract operations.

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Why is boosts matrix multiplication slower than mine?

I have implemented one matrix multiplication with boost::numeric::ublas::matrix (see my full, working boost code) Result result = read (); boost::numeric::ublas::matrix C; C = boost::numeric::ublas::prod(result.A, result.B); and another one…
Martin Thoma
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GDB Can't Display Boost uBLAS Matrix?

I have a successfully compiled program using Boost's implementation of uBLAS matricies. Alas, debugging with gdb is proving problematic as I could find no way to see the contents of my matrices while debugging. When I try to see an element of a…
Richard
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Remove non-generic template parameter on C

I'm using ublas for my matrix code, but I want it to be exchangeable, so I was doing this: typedef boost::numeric::ublas::matrix cMatrix; Today, I need to change some of this matrixes to bounded sizes, so I will also have this: typedef…
renatolond
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BOOST uBLAS matrix product extremely slow

Is there a way to improve the boost ublas product performance? I have two matrices A,B which i want to mulitply/add/sub/... In MATLAB vs. C++ i get the following times [s] for a 2000x2000 matrix Operations OPERATION | MATLAB | C++ (MSVC10) A + B …
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Creating a c_vector

Is it possible to create a c_vector with the values [12 398 -34] (as an example), in a single line? As far as I can see the only viable constructor is: c_vector(vector_expression const&) which takes a VectorExpression, which seem to be…
Shoe
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boost::ublas how to get determinant of int matrix?

I found the function that calculates the determinant of boost::ublas matrix: template ValType det_fast(const ublas::matrix& matrix) { // create a working copy of the input ublas::matrix mLu(matrix); …
AeroSun
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Why doesn't the arrow operator "->" work on boost::numeric::ublas::vector<...>::iterator?

Consider this code: struct CData { int bar() { return 1; } }; int main() { typedef boost::numeric::ublas::vector vec_data_t; vec_data_t foo; for (vec_data_t::iterator it = foo.begin(); it != foo.end(); …
oxygene
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why has uBLAS no `operator*(matrix, vector)`?

In the doc, they say We decided to use no operator overloading for ... They provide prod instead for these. But why? Is there any good reason? I like to do matrix * vector (as in most other languages). I like to understand why they did not…
Albert
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how do I pass the boost matrix prod() function as a multiplies function?

I'm trying to perform a matrix exponentiation, but I don't want to copy/paste my exponentiation function, and would rather use class templates. The problem is that for boost matrices, to multiply matrices, you use the prod function (instead of…
Brian
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uBLAS matrix clear memory

I have a uBLAS matrix, like so: boost::numeric::ublas::matrix mat(50000,50000); Once I'm done with a set of calculations on the matrix, I want its memory freed. I have been using mat.clear() which, according to the docs, "clears the…
Richard
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Can double's overflow to negative values?

Hi I am using the g++ compiler and am experiencing (what I think) is underflow of doubles, is this possible and if so how is the behaviour defined I have uploaded the csv format of the covariance matrix (51x51) here: http://pastebin.com/r0fx1qsx…
Aly
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Why can I initialize a regular Boost matrix like a scalar matrix?

Why does this work? It's not in the documentation anywhere... #include #include #include int main() { boost::numeric::ublas::matrix twoByTwoMat(2,2,-2); std::cout <<…
John Doe
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Boost uBLAS Matrix Reference

I'm wondering if it's possible to get the address of an individual element of a Boost uBLAS matrix? That is boost::numeric::ublas::matrix bob(3,3); some_function(&bob[2][2]); Now, of course the second line won't work... but I'd like it…
Richard
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What are, and how to use, iterator1 and iterator2 of Boost matrix?

I am looking for a way to iterate over elements of a Boost matrix using iterators. Documentation reports Matrix methods returning an iterator1 and iterator2: iterator1 begin1 () Returns a iterator1 pointing to the beginning of the matrix. iterator1…
Fanta
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identity_matrix/zero_matrix: do they allocate?

matrix classes identity_matrix and zero_matrix are templates with ALLOC as a second parameter. But do they really allocate memory?
Andrei R.
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