fix test

Author: lingium

stan/math/prim/prob/yule_simon_rng.hpp

@@ -2,6 +2,7 @@
 #define STAN_MATH_PRIM_PROB_YULE_SIMON_RNG_HPP
 
 #include <stan/math/prim/meta.hpp>
+#include <stan/math/prim/fun/log1m.hpp>
 #include <stan/math/prim/prob/exponential_rng.hpp>
 #include <stan/math/prim/prob/neg_binomial_rng.hpp>
 
@@ -38,8 +39,9 @@ inline auto yule_simon_rng(const T_alpha &alpha, RNG &rng) {
 
   VectorBuilder<true, int, T_alpha> output(size_w);
   for (size_t n = 0; n < size_w; ++n) {
-    double p = exp(-w_vec.val(n));
-    double odds_ratio_p = exp(log(p) - log1m(p));
+    double p = stan::math::exp(-w_vec.val(n));
+    double odds_ratio_p
+        = stan::math::exp(stan::math::log(p) - stan::math::log1m(p));
     output[n] = neg_binomial_rng(1.0, odds_ratio_p, rng) + 1;
   }
 

test/unit/math/prim/prob/yule_simon_test.cpp

@@ -38,21 +38,17 @@ TEST(ProbDistributionsYuleSimon, distributionCheck) {
 TEST(ProbDistributionsYuleSimon, error_check) {
   boost::random::mt19937 rng;
 
-  // Valid parameters should not throw
   EXPECT_NO_THROW(stan::math::yule_simon_rng(1.0, rng));
   EXPECT_NO_THROW(stan::math::yule_simon_rng(2.0, rng));
   EXPECT_NO_THROW(stan::math::yule_simon_rng(10.0, rng));
 
-  // Invalid parameters should throw domain_error
   EXPECT_THROW(stan::math::yule_simon_rng(-0.5, rng), std::domain_error);
   EXPECT_THROW(stan::math::yule_simon_rng(0.0, rng), std::domain_error);
   EXPECT_THROW(stan::math::yule_simon_rng(-10.0, rng), std::domain_error);
 
-  // Infinity should throw
   EXPECT_THROW(stan::math::yule_simon_rng(stan::math::positive_infinity(), rng),
                std::domain_error);
 
-  // NaN should throw
   EXPECT_THROW(stan::math::yule_simon_rng(stan::math::not_a_number(), rng),
                std::domain_error);
 }