Failing test for lbeta (stan-dev#1611)

Author: martinmodrak

test/unit/math/prim/scal/fun/lbeta_test.cpp

@@ -1,7 +1,10 @@
+#include <test/unit/math/expect_near_rel.hpp>
 #include <stan/math/prim/scal.hpp>
 #include <gtest/gtest.h>
 #include <cmath>
 #include <limits>
+#include <vector>
+
 
 TEST(MathFunctions, lbeta) {
   using stan::math::lbeta;
@@ -21,3 +24,28 @@ TEST(MathFunctions, lbeta_nan) {
 
   EXPECT_TRUE(std::isnan(stan::math::lbeta(nan, nan)));
 }
+
+namespace lbeta_test_internal {
+  struct TestValue {
+    double x;
+    double y;
+    double val;
+  };
+
+std::vector<TestValue> testValues = {  {8.e-8,7.e-11,23.3834004912898500586445},  {8.e-8,0.00002,16.3452312235394351410033},  {8.e-8,1.000000000001,16.3412392022725295437606},  {8.e-8,0.5,16.3412393131760679059067},  {8.e-8,2,16.3412391222725327438921},  {8.e-8,1624,16.3412385647081130254943},  {0.004,7.e-11,23.3825258913787298259023},  {0.004,0.00002,10.8247656947117878792194},  {0.004,1.000000000001,5.52146091786223987264715},  {0.004,0.5,5.52697992926150653113797},  {0.004,2,5.51746889659270898022044},  {0.004,1624,5.48959582574332555214719},  {1,7.e-11,23.3825258738791892190926},  {1,0.00002,10.8197782844102831106727},  {1,1.000000000001,-9.999999999995e-13},  {1,0.5,0.693147180559945309417232},  {1,2,-0.693147180559945309417232},  {1,1624,-7.39264752072162326054032},  {1.00000001,7.e-11,23.3825258738791892179411},  {1.00000001,0.00002,10.8197782844099541286699},  {1.00000001,1.000000000001,-1.00009999500064491739816e-8},  {1.00000001,0.5,0.693147174422888956122731},  {1.00000001,2,-0.693147195559945246917232},  {1.00000001,1624,-7.39264760042333353631934},  {5,7.e-11,23.3825258737333558857627},  {5,0.00002,10.8197366180283355258393},  {5,1.000000000001,-1.60943791243638370793409},  {5,0.5,-0.207395194346070587158746},  {5,2,-3.40119738166215537541324},  {5,1624,-33.7913357290267948074624},  {23,7.e-11,23.3825258736208322915813},  {23,0.00002,10.819704468465374949026},  {23,1.000000000001,-3.13549421593288398231784},  {23,0.5,-0.989947810259228199543883},  {23,2,-6.31354804627709531045369},  {23,1624,-121.714785277510463870251},  {19845,7.e-11,23.3825258731460863706715},  {19845,0.00002,10.8195688267825637640878},  {19845,1.000000000001,-9.89570736522763869861762},  {19845,0.5,-4.37548244086806082919414},  {19845,2,-19.7914651196913525680177},  {19845,1624,-5756.4146766727238501215},  {3000000000000000.0,3,-106.219018870176440545578},  {3000000000000000.0,100,-3204.60466298830574639047},  {3000000000000000.0,12895,-350396.988955562106921852},  {100000000000000000000.0,3,-137.461958399082795731692},  {100000000000000000000.0,100,-4246.03598061851596930944},  {100000000000000000000.0,12895,-484689.557363950217404711},};
+}
+
+TEST(MathFunctions, lbeta_precomputed) {
+  using lbeta_test_internal::TestValue;
+  using lbeta_test_internal::testValues;
+  using stan::test::expect_near_rel;
+
+  for (TestValue t : testValues) {
+
+    std::ostringstream msg;
+    msg << std::setprecision(22) << "x = " << t.x << ", y = " << t.y;
+
+    double val = stan::math::lbeta(t.x, t.y);
+    expect_near_rel(msg.str(), val, t.val);
+  }
+}