1 files changed, 24 insertions, 0 deletions
diff --git a/training/em_utils.h b/training/em_utils.h
new file mode 100644
index 00000000..37762978
--- /dev/null
+++ b/training/em_utils.h
@@ -0,0 +1,24 @@
+#ifndef _EM_UTILS_H_
+#define _EM_UTILS_H_
+
+#include "config.h"
+#ifdef HAVE_BOOST_DIGAMMA
+#include <boost/math/special_functions/digamma.hpp>
+using boost::math::digamma;
+#else
+#warning Using Mark Johnsons digamma()
+#include <cmath>
+inline double digamma(double x) {
+  double result = 0, xx, xx2, xx4;
+  assert(x > 0);
+  for ( ; x < 7; ++x)
+    result -= 1/x;
+  x -= 1.0/2.0;
+  xx = 1.0/x;
+  xx2 = xx*xx;
+  xx4 = xx2*xx2;
+  result += log(x)+(1./24.)*xx2-(7.0/960.0)*xx4+(31.0/8064.0)*xx4*xx2-(127.0/30720.0)*xx4*xx4;
+  return result;
+}
+#endif
+#endif