define FLT_EPSILON; be descriptive about upper_right_triangle() method

test/upperRightTriangle.cpp

@@ -0,0 +1,23 @@
+#include "test_macros.hpp"
+#include <matrix/math.hpp>
+
+using namespace matrix;
+
+int main()
+{
+    float data[9] = {1, 2, 3,
+                     4, 5, 6,
+                     7, 8, 10
+                    };
+    float urt[6] = {1, 2, 3, 5, 6, 10};
+
+    SquareMatrix<float, 3> A(data);
+
+    for(int i=0; i<6; i++) {
+        TEST(fabs(urt[i] - A.upper_right_triangle().data()[i]) < FLT_EPSILON);
+    }
+
+    return 0;
+}
+
+/* vim: set et fenc=utf-8 ff=unix sts=0 sw=4 ts=4 : */