Please create an account to participate in the Slashdot moderation system


Forgot your password?
Check out the new SourceForge HTML5 internet speed test! No Flash necessary and runs on all devices. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. ×

Journal npsimons's Journal: Boost UBLAS matrix iterators and templates - Solved

UPDATE: I had a look around, figured I would try substituting a std::vector<std::vector<double> > for the uBLAS matrix<double>, still got the same error. So I started looking better into templates (no, I'm not quite done with vol2 of "Thinking in C++") and found out about typename. Seems to fix the problem.

I know I should probably post this to stackoverflow or the Boost/UBLAS mailing list, but I figure there are plenty of smart people here at slashdot.

Let's say you are using UBLAS from Boost and you want to implement a cumulative summing function for matrices. Here's what I think is a fairly straightforward way to do it:

// For boost::numeric::ublas::matrix<>.
#include <boost/numeric/ublas/matrix.hpp>

// For std::partial_sum().
#include <numeric>

template<class T>
boost::numeric::ublas::matrix<T> cumSum
(const boost::numeric::ublas::matrix<T>& input_,
const bool& colWise_ = true)
using namespace boost::numeric::ublas;
using namespace std;

matrix<T> result_(input_);

if (colWise_)
for (matrix<T>::iterator2 colIter = result_.begin2();
colIter < result_.end2();
for (matrix<T>::iterator1 rowIter = result_.begin1();
rowIter < result_.end1();

return result_;

For now, I'm ignoring completely templatizing this to make the row-wise/column-wise distinction disappear in the code and focusing on just getting it working. Only it doesn't work; won't compile. Couldn't figure out why, but g++ kept saying it was expecting a ';' before colIter and rowIter. I had a hunch and replaced one of the iterator's 'T's with 'double' and it stopped complaining about that one. Am I missing something, or does UBLAS not implement iterators properly?What am I missing?

This discussion has been archived. No new comments can be posted.

Boost UBLAS matrix iterators and templates - Solved

Comments Filter:

Much of the excitement we get out of our work is that we don't really know what we are doing. -- E. Dijkstra