Adding tests for trigamma

src/mlpack/tests/trigamma_test.cpp

@@ -0,0 +1,34 @@
+/**
+ * @file tests/digamma_test.cpp
+ * @author Gopi Tatiraju
+ * 
+ * Test the trigamma function.
+ *
+ * mlpack is free software; you may redistribute it and/or modify it under the
+ * terms of the 3-clause BSD license.  You should have received a copy of the
+ * 3-clause BSD license along with mlpack.  If not, see
+ * http://www.opensource.org/licenses/BSD-3-Clause for more information.
+ */
+#include <mlpack/core.hpp>
+#include <mlpack/core/math/trigamma.hpp>
+
+#include "catch.hpp"
+#include "test_catch_tools.hpp"
+
+using namespace mlpack;
+using namespace math;
+
+/**
+ * Test the output of trigamma for input values.
+ */
+TEST_CASE("Trigamma", "[TrigammaTest]")
+{
+  arma::mat data;
+
+  if (!data::Load("trigamma_data.csv", data, true, false))
+    FAIL("Cannot load data trigamma_data.csv");
+
+  for (size_t i = 0; i < data.n_rows; i++)
+    REQUIRE(Trigamma(data(i, 0)) == Approx(data(i, 1)).epsilon(1e-7));
+}
+