<p>No, I hadn't touched it - thanks for the tip!</p>

<p>I've now uncommented the required line in /include/armadillo_bits/config.hpp and recompiled mlpack. However, I now get an out of memory error:</p>

<p>error: arma::memory::acquire(): out of memory</p>

<p>terminate called after throwing an instance of 'std::bad_alloc'<br>
  what():  std::bad_alloc</p>

<p>Program received signal SIGABRT, Aborted.</p>

<p>When I look at the backtrace in gdb, I find that upon initialising the zero matrix, arma requests 4294970366 (i.e. 2^32 +/- rounding error) elements and then fails to allocate memory for it</p>

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