Fix pessimization on unaffected platforms

Author: mborland

include/boost/math/special_functions/beta.hpp

@@ -586,7 +586,7 @@ T ibeta_series(T a, T b, T x, T s0, const Lanczos&, bool normalised, T* p_deriva
          if(a * b < bgh * 10)
             result *= exp((b - 0.5f) * boost::math::log1p(a / bgh, pol));
          else
-            result *= pow(cgh / bgh, T(b - 0.5f));
+            result *= pow(cgh / bgh, T(b - T(0.5)));
          result *= pow(x * cgh / agh, a);
          result *= sqrt(agh / boost::math::constants::e<T>());
 

include/boost/math/special_functions/detail/bessel_jy_series.hpp

@@ -236,7 +236,12 @@ T bessel_yn_small_z(int n, T z, T* scale, const Policy& pol)
    }
    else
    {
+      #if (defined(__GNUC__) && __GNUC__ == 13)
       auto p = static_cast<T>(pow(z / 2, T(n)));
+      #else
+      auto p = static_cast<T>(pow(z / 2, n));
+      #endif
+      
       T result = -((boost::math::factorial<T>(n - 1, pol) / constants::pi<T>()));
       if(p * tools::max_value<T>() < result)
       {

include/boost/math/special_functions/detail/hypergeometric_pFq_checked_series.hpp

@@ -146,7 +146,13 @@
                  return std::make_pair(r, r);
               }
               std::pair<Real, Real> r = hypergeometric_pFq_checked_series_impl(aj, bj, Real(1 / z), pol, termination, log_scale);
+              
+              #if (defined(__GNUC__) && __GNUC__ == 13)
               Real mul = pow(-z, Real(-*aj.begin()));
+              #else
+              Real mul = pow(-z, -*aj.begin());
+              #endif
+              
               r.first *= mul;
               r.second *= mul;
               return r;