<p>In <a href="https://github.com/mlpack/mlpack/pull/408#discussion_r25187024">src/mlpack/tests/arma_extend_test.cpp</a>:</p>
<pre style='color:#555'>&gt; +
&gt; +  mat Y = X;
&gt; +
&gt; +  BOOST_REQUIRE(arma::inplace_transpose(X) == false);
&gt; +  BOOST_REQUIRE_EQUAL(X.n_rows, 4);
&gt; +  BOOST_REQUIRE_EQUAL(X.n_cols, 2);
&gt; +
&gt; +  for (size_t i = 0; i &lt; X.n_rows; ++i)
&gt; +    for (size_t j = 0; j &lt; X.n_cols; ++j)
&gt; +      BOOST_REQUIRE_CLOSE(X.at(i, j), Y.at(j, i), 1e-5);
&gt; +}
&gt; +
&gt; +/**
&gt; + * Try to transpose using low-mem method.
&gt; + */
&gt; +BOOST_AUTO_TEST_CASE(InplaceTransposeLowMemTest)
</pre>
<p>Yeah, this test will probably usually cause a user's system to start swapping (which is a bad thing).  Can you think of a better way to perform this test without actually allocating such a huge matrix?  If not, the code contribution is sufficiently simple that I'll take it without tests.  After all, it depends on Armadillo, and we can assume that the Armadillo transposition code is sufficiently well-tested.</p>

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