move widely duplicated math functions into m.h header

1 files changed, 75 insertions, 0 deletions

diff --git a/utils/m_test.cc b/utils/m_test.cc
new file mode 100644
index 00000000..fca8f895
--- /dev/null
+++ b/utils/m_test.cc
@@ -0,0 +1,75 @@
+#include "m.h"
+
+#include <iostream>
+#include <gtest/gtest.h>
+#include <cassert>
+
+using namespace std;
+
+class MTest : public testing::Test {
+ public:
+  MTest() {}
+ protected:
+  virtual void SetUp() { }
+  virtual void TearDown() { }
+};
+
+TEST_F(MTest, Poisson) {
+  double prev = 1.0;
+  double tot = 0;
+  for (int i = 0; i < 10; ++i) {
+    double p = Md::log_poisson(i, 0.99);
+    cerr << "p(i=" << i << ") = " << exp(p) << endl;
+    EXPECT_LT(p, prev);
+    tot += exp(p);
+    prev = p;
+  }
+  cerr << "  tot=" << tot << endl;
+  EXPECT_LE(tot, 1.0);
+}
+
+TEST_F(MTest, YuleSimon) {
+  double prev = 1.0;
+  double tot = 0;
+  for (int i = 0; i < 10; ++i) {
+    double p = Md::log_yule_simon(i, 1.0);
+    cerr << "p(i=" << i << ") = " << exp(p) << endl;
+    EXPECT_LT(p, prev);
+    tot += exp(p);
+    prev = p;
+  }
+  cerr << "  tot=" << tot << endl;
+  EXPECT_LE(tot, 1.0);
+}
+
+TEST_F(MTest, LogGeometric) {
+  double prev = 1.0;
+  double tot = 0;
+  for (int i = 0; i < 10; ++i) {
+    double p = Md::log_geometric(i, 0.5);
+    cerr << "p(i=" << i << ") = " << exp(p) << endl;
+    EXPECT_LT(p, prev);
+    tot += exp(p);
+    prev = p;
+  }
+  cerr << "  tot=" << tot << endl;
+  EXPECT_LE(tot, 1.0);
+}
+
+TEST_F(MTest, GeneralizedFactorial) {
+  for (double i = 0.3; i < 10000; i += 0.4) {
+    double a = Md::log_generalized_factorial(1.0, i);
+    double b = lgamma(1.0 + i);
+    EXPECT_FLOAT_EQ(a,b);
+  }
+  double gf_3_6 = 3.0 * 4.0 * 5.0 * 6.0 * 7.0 * 8.0;
+  EXPECT_FLOAT_EQ(Md::log_generalized_factorial(3.0, 6.0), std::log(gf_3_6));
+  double gf_314_6 = 3.14 * 4.14 * 5.14 * 6.14 * 7.14 * 8.14;
+  EXPECT_FLOAT_EQ(Md::log_generalized_factorial(3.14, 6.0), std::log(gf_314_6));
+}
+
+int main(int argc, char** argv) {
+  testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}
+