diff --git a/Eigen/src/Core/arch/AVX/PacketMath.h b/Eigen/src/Core/arch/AVX/PacketMath.h
index 50db0e5c0..f5c18f63f 100644
--- a/Eigen/src/Core/arch/AVX/PacketMath.h
+++ b/Eigen/src/Core/arch/AVX/PacketMath.h
@@ -147,7 +147,9 @@ struct packet_traits<Eigen::half> : default_packet_traits {
     HasRound  = 1,
     HasFloor  = 1,
     HasCeil   = 1,
-    HasRint   = 1
+    HasRint   = 1,
+    HasBessel = 1,
+    HasNdtri  = 1,
   };
 };
 
@@ -189,7 +191,9 @@ struct packet_traits<bfloat16> : default_packet_traits {
     HasRound = 1,
     HasFloor = 1,
     HasCeil = 1,
-    HasRint = 1
+    HasRint = 1,
+    HasBessel = 1,
+    HasNdtri  = 1,
   };
 };
 #endif
diff --git a/Eigen/src/Core/arch/AVX512/PacketMath.h b/Eigen/src/Core/arch/AVX512/PacketMath.h
index 2bbcd802c..a001fb186 100644
--- a/Eigen/src/Core/arch/AVX512/PacketMath.h
+++ b/Eigen/src/Core/arch/AVX512/PacketMath.h
@@ -86,7 +86,9 @@ struct packet_traits<half> : default_packet_traits {
     HasRound  = 1,
     HasFloor  = 1,
     HasCeil   = 1,
-    HasRint   = 1
+    HasRint   = 1,
+    HasBessel = 1,
+    HasNdtri  = 1,
   };
 };
 
diff --git a/Eigen/src/Core/arch/Default/Half.h b/Eigen/src/Core/arch/Default/Half.h
index b9a8a46aa..76156c416 100644
--- a/Eigen/src/Core/arch/Default/Half.h
+++ b/Eigen/src/Core/arch/Default/Half.h
@@ -58,7 +58,7 @@
 
 #define F16_PACKET_FUNCTION(PACKET_F, PACKET_F16, METHOD)           \
   template <>                                                       \
-  EIGEN_DEFINE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS EIGEN_UNUSED  \
+  EIGEN_STRONG_INLINE EIGEN_DEVICE_FUNC EIGEN_UNUSED                \
   PACKET_F16 METHOD<PACKET_F16>(const PACKET_F16& _x) {             \
     return float2half(METHOD<PACKET_F>(half2float(_x)));            \
   }
diff --git a/Eigen/src/Core/arch/NEON/PacketMath.h b/Eigen/src/Core/arch/NEON/PacketMath.h
index fd6b4f137..b60f4143f 100644
--- a/Eigen/src/Core/arch/NEON/PacketMath.h
+++ b/Eigen/src/Core/arch/NEON/PacketMath.h
@@ -192,7 +192,9 @@ struct packet_traits<float> : default_packet_traits
     HasExp  = 1,
     HasSqrt = 1,
     HasTanh = EIGEN_FAST_MATH,
-    HasErf  = EIGEN_FAST_MATH
+    HasErf  = EIGEN_FAST_MATH,
+    HasBessel = 0,  // Issues with accuracy.
+    HasNdtri = 0
   };
 };
 
@@ -3321,7 +3323,9 @@ template<> struct packet_traits<bfloat16> : default_packet_traits
     HasExp  = 1,
     HasSqrt = 0,
     HasTanh = EIGEN_FAST_MATH,
-    HasErf  = EIGEN_FAST_MATH
+    HasErf  = EIGEN_FAST_MATH,
+    HasBessel = 0,  // Issues with accuracy.
+    HasNdtri = 0,
   };
 };
 
@@ -3887,7 +3891,10 @@ struct packet_traits<Eigen::half> : default_packet_traits {
     HasCos = 0,
     HasLog = 0,
     HasExp = 0,
-    HasSqrt = 1
+    HasSqrt = 1,
+    HasErf = EIGEN_FAST_MATH,
+    HasBessel = 0,  // Issues with accuracy.
+    HasNdtri = 0,
   };
 };
 
diff --git a/unsupported/Eigen/SpecialFunctions b/unsupported/Eigen/SpecialFunctions
index dda6618de..f6a2460e6 100644
--- a/unsupported/Eigen/SpecialFunctions
+++ b/unsupported/Eigen/SpecialFunctions
@@ -61,23 +61,36 @@ namespace Eigen {
 }
 
 #include "src/SpecialFunctions/BesselFunctionsImpl.h"
-#include "src/SpecialFunctions/BesselFunctionsPacketMath.h"
 #include "src/SpecialFunctions/BesselFunctionsBFloat16.h"
 #include "src/SpecialFunctions/BesselFunctionsHalf.h"
+#include "src/SpecialFunctions/BesselFunctionsPacketMath.h"
 #include "src/SpecialFunctions/BesselFunctionsFunctors.h"
 #include "src/SpecialFunctions/BesselFunctionsArrayAPI.h"
 #include "src/SpecialFunctions/SpecialFunctionsImpl.h"
 #if defined(EIGEN_HIPCC)
 #include "src/SpecialFunctions/HipVectorCompatibility.h"
 #endif
-#include "src/SpecialFunctions/SpecialFunctionsPacketMath.h"
 #include "src/SpecialFunctions/SpecialFunctionsBFloat16.h"
 #include "src/SpecialFunctions/SpecialFunctionsHalf.h"
+#include "src/SpecialFunctions/SpecialFunctionsPacketMath.h"
 #include "src/SpecialFunctions/SpecialFunctionsFunctors.h"
 #include "src/SpecialFunctions/SpecialFunctionsArrayAPI.h"
 
+#if defined EIGEN_VECTORIZE_AVX512
+  #include "src/SpecialFunctions/arch/AVX/BesselFunctions.h"
+  #include "src/SpecialFunctions/arch/AVX/SpecialFunctions.h"
+  #include "src/SpecialFunctions/arch/AVX512/BesselFunctions.h"
+  #include "src/SpecialFunctions/arch/AVX512/SpecialFunctions.h"
+#elif defined EIGEN_VECTORIZE_AVX
+  #include "src/SpecialFunctions/arch/AVX/BesselFunctions.h"
+  #include "src/SpecialFunctions/arch/AVX/SpecialFunctions.h"
+#elif defined EIGEN_VECTORIZE_NEON
+  #include "src/SpecialFunctions/arch/NEON/BesselFunctions.h"
+  #include "src/SpecialFunctions/arch/NEON/SpecialFunctions.h"
+#endif
+
 #if defined EIGEN_VECTORIZE_GPU
-  #include "src/SpecialFunctions/arch/GPU/GpuSpecialFunctions.h"
+  #include "src/SpecialFunctions/arch/GPU/SpecialFunctions.h"
 #endif
 
 namespace Eigen {
diff --git a/unsupported/Eigen/src/SpecialFunctions/BesselFunctionsImpl.h b/unsupported/Eigen/src/SpecialFunctions/BesselFunctionsImpl.h
index a9b6ad940..24812be1b 100644
--- a/unsupported/Eigen/src/SpecialFunctions/BesselFunctionsImpl.h
+++ b/unsupported/Eigen/src/SpecialFunctions/BesselFunctionsImpl.h
@@ -46,7 +46,7 @@ struct bessel_i0e_retval {
   typedef Scalar type;
 };
 
-template <typename T, typename ScalarType>
+template <typename T, typename ScalarType = typename unpacket_traits<T>::type>
 struct generic_i0e {
   EIGEN_DEVICE_FUNC
   static EIGEN_STRONG_INLINE T run(const T&) {
@@ -201,11 +201,11 @@ struct generic_i0e<T, double> {
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_i0e_impl {
   EIGEN_DEVICE_FUNC
-  static EIGEN_STRONG_INLINE Scalar run(const Scalar x) {
-    return generic_i0e<Scalar, Scalar>::run(x);
+  static EIGEN_STRONG_INLINE T run(const T x) {
+    return generic_i0e<T>::run(x);
   }
 };
 
@@ -214,7 +214,7 @@ struct bessel_i0_retval {
   typedef Scalar type;
 };
 
-template <typename T, typename ScalarType>
+template <typename T, typename ScalarType = typename unpacket_traits<T>::type>
 struct generic_i0 {
   EIGEN_DEVICE_FUNC
   static EIGEN_STRONG_INLINE T run(const T& x) {
@@ -224,11 +224,11 @@ struct generic_i0 {
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_i0_impl {
   EIGEN_DEVICE_FUNC
-  static EIGEN_STRONG_INLINE Scalar run(const Scalar x) {
-    return generic_i0<Scalar, Scalar>::run(x);
+  static EIGEN_STRONG_INLINE T run(const T x) {
+    return generic_i0<T>::run(x);
   }
 };
 
@@ -237,7 +237,7 @@ struct bessel_i1e_retval {
   typedef Scalar type;
 };
 
-template <typename T, typename ScalarType>
+template <typename T, typename ScalarType = typename unpacket_traits<T>::type >
 struct generic_i1e {
   EIGEN_DEVICE_FUNC
   static EIGEN_STRONG_INLINE T run(const T&) {
@@ -396,20 +396,20 @@ struct generic_i1e<T, double> {
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_i1e_impl {
   EIGEN_DEVICE_FUNC
-  static EIGEN_STRONG_INLINE Scalar run(const Scalar x) {
-    return generic_i1e<Scalar, Scalar>::run(x);
+  static EIGEN_STRONG_INLINE T run(const T x) {
+    return generic_i1e<T>::run(x);
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_i1_retval {
-  typedef Scalar type;
+  typedef T type;
 };
 
-template <typename T, typename ScalarType>
+template <typename T, typename ScalarType = typename unpacket_traits<T>::type>
 struct generic_i1 {
   EIGEN_DEVICE_FUNC
   static EIGEN_STRONG_INLINE T run(const T& x) {
@@ -419,20 +419,20 @@ struct generic_i1 {
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_i1_impl {
   EIGEN_DEVICE_FUNC
-  static EIGEN_STRONG_INLINE Scalar run(const Scalar x) {
-    return generic_i1<Scalar, Scalar>::run(x);
+  static EIGEN_STRONG_INLINE T run(const T x) {
+    return generic_i1<T>::run(x);
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_k0e_retval {
-  typedef Scalar type;
+  typedef T type;
 };
 
-template <typename T, typename ScalarType>
+template <typename T, typename ScalarType = typename unpacket_traits<T>::type>
 struct generic_k0e {
   EIGEN_DEVICE_FUNC
   static EIGEN_STRONG_INLINE T run(const T&) {
@@ -582,20 +582,20 @@ struct generic_k0e<T, double> {
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_k0e_impl {
   EIGEN_DEVICE_FUNC
-  static EIGEN_STRONG_INLINE Scalar run(const Scalar x) {
-    return generic_k0e<Scalar, Scalar>::run(x);
+  static EIGEN_STRONG_INLINE T run(const T x) {
+    return generic_k0e<T>::run(x);
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_k0_retval {
-  typedef Scalar type;
+  typedef T type;
 };
 
-template <typename T, typename ScalarType>
+template <typename T, typename ScalarType = typename unpacket_traits<T>::type>
 struct generic_k0 {
   EIGEN_DEVICE_FUNC
   static EIGEN_STRONG_INLINE T run(const T&) {
@@ -754,20 +754,20 @@ struct generic_k0<T, double> {
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_k0_impl {
   EIGEN_DEVICE_FUNC
-  static EIGEN_STRONG_INLINE Scalar run(const Scalar x) {
-    return generic_k0<Scalar, Scalar>::run(x);
+  static EIGEN_STRONG_INLINE T run(const T x) {
+    return generic_k0<T>::run(x);
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_k1e_retval {
-  typedef Scalar type;
+  typedef T type;
 };
 
-template <typename T, typename ScalarType>
+template <typename T, typename ScalarType = typename unpacket_traits<T>::type>
 struct generic_k1e {
   EIGEN_DEVICE_FUNC
   static EIGEN_STRONG_INLINE T run(const T&) {
@@ -910,20 +910,20 @@ struct generic_k1e<T, double> {
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_k1e_impl {
   EIGEN_DEVICE_FUNC
-  static EIGEN_STRONG_INLINE Scalar run(const Scalar x) {
-    return generic_k1e<Scalar, Scalar>::run(x);
+  static EIGEN_STRONG_INLINE T run(const T x) {
+    return generic_k1e<T>::run(x);
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_k1_retval {
-  typedef Scalar type;
+  typedef T type;
 };
 
-template <typename T, typename ScalarType>
+template <typename T, typename ScalarType = typename unpacket_traits<T>::type>
 struct generic_k1 {
   EIGEN_DEVICE_FUNC
   static EIGEN_STRONG_INLINE T run(const T&) {
@@ -1076,20 +1076,20 @@ struct generic_k1<T, double> {
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_k1_impl {
   EIGEN_DEVICE_FUNC
-  static EIGEN_STRONG_INLINE Scalar run(const Scalar x) {
-    return generic_k1<Scalar, Scalar>::run(x);
+  static EIGEN_STRONG_INLINE T run(const T x) {
+    return generic_k1<T>::run(x);
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_j0_retval {
-  typedef Scalar type;
+  typedef T type;
 };
 
-template <typename T, typename ScalarType>
+template <typename T, typename ScalarType = typename unpacket_traits<T>::type>
 struct generic_j0 {
   EIGEN_DEVICE_FUNC
   static EIGEN_STRONG_INLINE T run(const T&) {
@@ -1276,20 +1276,20 @@ struct generic_j0<T, double> {
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_j0_impl {
   EIGEN_DEVICE_FUNC
-  static EIGEN_STRONG_INLINE Scalar run(const Scalar x) {
-    return generic_j0<Scalar, Scalar>::run(x);
+  static EIGEN_STRONG_INLINE T run(const T x) {
+    return generic_j0<T>::run(x);
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_y0_retval {
-  typedef Scalar type;
+  typedef T type;
 };
 
-template <typename T, typename ScalarType>
+template <typename T, typename ScalarType = typename unpacket_traits<T>::type>
 struct generic_y0 {
   EIGEN_DEVICE_FUNC
   static EIGEN_STRONG_INLINE T run(const T&) {
@@ -1474,20 +1474,20 @@ struct generic_y0<T, double> {
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_y0_impl {
   EIGEN_DEVICE_FUNC
-  static EIGEN_STRONG_INLINE Scalar run(const Scalar x) {
-    return generic_y0<Scalar, Scalar>::run(x);
+  static EIGEN_STRONG_INLINE T run(const T x) {
+    return generic_y0<T>::run(x);
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_j1_retval {
-  typedef Scalar type;
+  typedef T type;
 };
 
-template <typename T, typename ScalarType>
+template <typename T, typename ScalarType = typename unpacket_traits<T>::type>
 struct generic_j1 {
   EIGEN_DEVICE_FUNC
   static EIGEN_STRONG_INLINE T run(const T&) {
@@ -1665,20 +1665,20 @@ struct generic_j1<T, double> {
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_j1_impl {
   EIGEN_DEVICE_FUNC
-  static EIGEN_STRONG_INLINE Scalar run(const Scalar x) {
-    return generic_j1<Scalar, Scalar>::run(x);
+  static EIGEN_STRONG_INLINE T run(const T x) {
+    return generic_j1<T>::run(x);
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_y1_retval {
-  typedef Scalar type;
+  typedef T type;
 };
 
-template <typename T, typename ScalarType>
+template <typename T, typename ScalarType = typename unpacket_traits<T>::type>
 struct generic_y1 {
   EIGEN_DEVICE_FUNC
   static EIGEN_STRONG_INLINE T run(const T&) {
@@ -1868,11 +1868,11 @@ struct generic_y1<T, double> {
   }
 };
 
-template <typename Scalar>
+template <typename T>
 struct bessel_y1_impl {
   EIGEN_DEVICE_FUNC
-  static EIGEN_STRONG_INLINE Scalar run(const Scalar x) {
-    return generic_y1<Scalar, Scalar>::run(x);
+  static EIGEN_STRONG_INLINE T run(const T x) {
+    return generic_y1<T>::run(x);
   }
 };
 
diff --git a/unsupported/Eigen/src/SpecialFunctions/BesselFunctionsPacketMath.h b/unsupported/Eigen/src/SpecialFunctions/BesselFunctionsPacketMath.h
index efc6d9c8f..943d10f6a 100644
--- a/unsupported/Eigen/src/SpecialFunctions/BesselFunctionsPacketMath.h
+++ b/unsupported/Eigen/src/SpecialFunctions/BesselFunctionsPacketMath.h
@@ -19,8 +19,7 @@ namespace internal {
 template <typename Packet>
 EIGEN_DEVICE_FUNC EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
 Packet pbessel_i0(const Packet& x) {
-  typedef typename unpacket_traits<Packet>::type ScalarType;
-  using internal::generic_i0; return generic_i0<Packet, ScalarType>::run(x);
+  return numext::bessel_i0(x);
 }
 
 /** \internal \returns the exponentially scaled modified Bessel function of
@@ -28,8 +27,7 @@ Packet pbessel_i0(const Packet& x) {
 template <typename Packet>
 EIGEN_DEVICE_FUNC EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
 Packet pbessel_i0e(const Packet& x) {
-  typedef typename unpacket_traits<Packet>::type ScalarType;
-  using internal::generic_i0e; return generic_i0e<Packet, ScalarType>::run(x);
+  return numext::bessel_i0e(x);
 }
 
 /** \internal \returns the exponentially scaled modified Bessel function of
@@ -37,8 +35,7 @@ Packet pbessel_i0e(const Packet& x) {
 template <typename Packet>
 EIGEN_DEVICE_FUNC EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
 Packet pbessel_i1(const Packet& x) {
-  typedef typename unpacket_traits<Packet>::type ScalarType;
-  using internal::generic_i1; return generic_i1<Packet, ScalarType>::run(x);
+  return numext::bessel_i1(x);
 }
 
 /** \internal \returns the exponentially scaled modified Bessel function of
@@ -46,8 +43,7 @@ Packet pbessel_i1(const Packet& x) {
 template <typename Packet>
 EIGEN_DEVICE_FUNC EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
 Packet pbessel_i1e(const Packet& x) {
-  typedef typename unpacket_traits<Packet>::type ScalarType;
-  using internal::generic_i1e; return generic_i1e<Packet, ScalarType>::run(x);
+  return numext::bessel_i1e(x);
 }
 
 /** \internal \returns the exponentially scaled modified Bessel function of
@@ -55,8 +51,7 @@ Packet pbessel_i1e(const Packet& x) {
 template <typename Packet>
 EIGEN_DEVICE_FUNC EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
 Packet pbessel_j0(const Packet& x) {
-  typedef typename unpacket_traits<Packet>::type ScalarType;
-  using internal::generic_j0; return generic_j0<Packet, ScalarType>::run(x);
+  return numext::bessel_j0(x);
 }
 
 /** \internal \returns the exponentially scaled modified Bessel function of
@@ -64,8 +59,7 @@ Packet pbessel_j0(const Packet& x) {
 template <typename Packet>
 EIGEN_DEVICE_FUNC EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
 Packet pbessel_j1(const Packet& x) {
-  typedef typename unpacket_traits<Packet>::type ScalarType;
-  using internal::generic_j1; return generic_j1<Packet, ScalarType>::run(x);
+  return numext::bessel_j1(x);
 }
 
 /** \internal \returns the exponentially scaled modified Bessel function of
@@ -73,8 +67,7 @@ Packet pbessel_j1(const Packet& x) {
 template <typename Packet>
 EIGEN_DEVICE_FUNC EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
 Packet pbessel_y0(const Packet& x) {
-  typedef typename unpacket_traits<Packet>::type ScalarType;
-  using internal::generic_y0; return generic_y0<Packet, ScalarType>::run(x);
+  return numext::bessel_y0(x);
 }
 
 /** \internal \returns the exponentially scaled modified Bessel function of
@@ -82,8 +75,7 @@ Packet pbessel_y0(const Packet& x) {
 template <typename Packet>
 EIGEN_DEVICE_FUNC EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
 Packet pbessel_y1(const Packet& x) {
-  typedef typename unpacket_traits<Packet>::type ScalarType;
-  using internal::generic_y1; return generic_y1<Packet, ScalarType>::run(x);
+  return numext::bessel_y1(x);
 }
 
 /** \internal \returns the exponentially scaled modified Bessel function of
@@ -91,8 +83,7 @@ Packet pbessel_y1(const Packet& x) {
 template <typename Packet>
 EIGEN_DEVICE_FUNC EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
 Packet pbessel_k0(const Packet& x) {
-  typedef typename unpacket_traits<Packet>::type ScalarType;
-  using internal::generic_k0; return generic_k0<Packet, ScalarType>::run(x);
+  return numext::bessel_k0(x);
 }
 
 /** \internal \returns the exponentially scaled modified Bessel function of
@@ -100,8 +91,7 @@ Packet pbessel_k0(const Packet& x) {
 template <typename Packet>
 EIGEN_DEVICE_FUNC EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
 Packet pbessel_k0e(const Packet& x) {
-  typedef typename unpacket_traits<Packet>::type ScalarType;
-  using internal::generic_k0e; return generic_k0e<Packet, ScalarType>::run(x);
+  return numext::bessel_k0e(x);
 }
 
 /** \internal \returns the exponentially scaled modified Bessel function of
@@ -109,8 +99,7 @@ Packet pbessel_k0e(const Packet& x) {
 template <typename Packet>
 EIGEN_DEVICE_FUNC EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
 Packet pbessel_k1(const Packet& x) {
-  typedef typename unpacket_traits<Packet>::type ScalarType;
-  using internal::generic_k1; return generic_k1<Packet, ScalarType>::run(x);
+  return numext::bessel_k1(x);
 }
 
 /** \internal \returns the exponentially scaled modified Bessel function of
@@ -118,8 +107,7 @@ Packet pbessel_k1(const Packet& x) {
 template <typename Packet>
 EIGEN_DEVICE_FUNC EIGEN_DECLARE_FUNCTION_ALLOWING_MULTIPLE_DEFINITIONS
 Packet pbessel_k1e(const Packet& x) {
-  typedef typename unpacket_traits<Packet>::type ScalarType;
-  using internal::generic_k1e; return generic_k1e<Packet, ScalarType>::run(x);
+  return numext::bessel_k1e(x);
 }
 
 } // end namespace internal
diff --git a/unsupported/Eigen/src/SpecialFunctions/SpecialFunctionsImpl.h b/unsupported/Eigen/src/SpecialFunctions/SpecialFunctionsImpl.h
index 648eb053e..cfc13aff7 100644
--- a/unsupported/Eigen/src/SpecialFunctions/SpecialFunctionsImpl.h
+++ b/unsupported/Eigen/src/SpecialFunctions/SpecialFunctionsImpl.h
@@ -348,7 +348,7 @@ EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE T generic_fast_erf_float(const T& a_x) {
 template <typename T>
 struct erf_impl {
   EIGEN_DEVICE_FUNC
-  static EIGEN_STRONG_INLINE T run(const T x) {
+  static EIGEN_STRONG_INLINE T run(const T& x) {
     return generic_fast_erf_float(x);
   }
 };
@@ -490,7 +490,8 @@ struct erfc_impl<double> {
 template<typename T>
 EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE T flipsign(
     const T& should_flipsign, const T& x) {
-  const T sign_mask = pset1<T>(-0.0);
+  typedef typename unpacket_traits<T>::type Scalar;
+  const T sign_mask = pset1<T>(Scalar(-0.0));
   T sign_bit = pand<T>(should_flipsign, sign_mask);
   return pxor<T>(sign_bit, x);
 }
diff --git a/unsupported/Eigen/src/SpecialFunctions/arch/AVX/BesselFunctions.h b/unsupported/Eigen/src/SpecialFunctions/arch/AVX/BesselFunctions.h
new file mode 100644
index 000000000..2d7669209
--- /dev/null
+++ b/unsupported/Eigen/src/SpecialFunctions/arch/AVX/BesselFunctions.h
@@ -0,0 +1,46 @@
+#ifndef EIGEN_AVX_BESSELFUNCTIONS_H
+#define EIGEN_AVX_BESSELFUNCTIONS_H
+
+namespace Eigen {
+namespace internal {
+
+F16_PACKET_FUNCTION(Packet8f, Packet8h, pbessel_i0)
+BF16_PACKET_FUNCTION(Packet8f, Packet8bf, pbessel_i0)
+
+F16_PACKET_FUNCTION(Packet8f, Packet8h, pbessel_i0e)
+BF16_PACKET_FUNCTION(Packet8f, Packet8bf, pbessel_i0e)
+
+F16_PACKET_FUNCTION(Packet8f, Packet8h, pbessel_i1)
+BF16_PACKET_FUNCTION(Packet8f, Packet8bf, pbessel_i1)
+
+F16_PACKET_FUNCTION(Packet8f, Packet8h, pbessel_i1e)
+BF16_PACKET_FUNCTION(Packet8f, Packet8bf, pbessel_i1e)
+
+F16_PACKET_FUNCTION(Packet8f, Packet8h, pbessel_j0)
+BF16_PACKET_FUNCTION(Packet8f, Packet8bf, pbessel_j0)
+
+F16_PACKET_FUNCTION(Packet8f, Packet8h, pbessel_j1)
+BF16_PACKET_FUNCTION(Packet8f, Packet8bf, pbessel_j1)
+
+F16_PACKET_FUNCTION(Packet8f, Packet8h, pbessel_k0)
+BF16_PACKET_FUNCTION(Packet8f, Packet8bf, pbessel_k0)
+
+F16_PACKET_FUNCTION(Packet8f, Packet8h, pbessel_k0e)
+BF16_PACKET_FUNCTION(Packet8f, Packet8bf, pbessel_k0e)
+
+F16_PACKET_FUNCTION(Packet8f, Packet8h, pbessel_k1)
+BF16_PACKET_FUNCTION(Packet8f, Packet8bf, pbessel_k1)
+
+F16_PACKET_FUNCTION(Packet8f, Packet8h, pbessel_k1e)
+BF16_PACKET_FUNCTION(Packet8f, Packet8bf, pbessel_k1e)
+
+F16_PACKET_FUNCTION(Packet8f, Packet8h, pbessel_y0)
+BF16_PACKET_FUNCTION(Packet8f, Packet8bf, pbessel_y0)
+
+F16_PACKET_FUNCTION(Packet8f, Packet8h, pbessel_y1)
+BF16_PACKET_FUNCTION(Packet8f, Packet8bf, pbessel_y1)
+
+}  // namespace internal
+}  // namespace Eigen
+
+#endif  // EIGEN_AVX_BESSELFUNCTIONS_H
diff --git a/unsupported/Eigen/src/SpecialFunctions/arch/AVX/SpecialFunctions.h b/unsupported/Eigen/src/SpecialFunctions/arch/AVX/SpecialFunctions.h
new file mode 100644
index 000000000..35e62a8ac
--- /dev/null
+++ b/unsupported/Eigen/src/SpecialFunctions/arch/AVX/SpecialFunctions.h
@@ -0,0 +1,16 @@
+#ifndef EIGEN_AVX_SPECIALFUNCTIONS_H
+#define EIGEN_AVX_SPECIALFUNCTIONS_H
+
+namespace Eigen {
+namespace internal {
+
+F16_PACKET_FUNCTION(Packet8f, Packet8h, perf)
+BF16_PACKET_FUNCTION(Packet8f, Packet8bf, perf)
+
+F16_PACKET_FUNCTION(Packet8f, Packet8h, pndtri)
+BF16_PACKET_FUNCTION(Packet8f, Packet8bf, pndtri)
+
+}  // namespace internal
+}  // namespace Eigen
+
+#endif  // EIGEN_AVX_SPECIAL_FUNCTIONS_H
diff --git a/unsupported/Eigen/src/SpecialFunctions/arch/AVX512/BesselFunctions.h b/unsupported/Eigen/src/SpecialFunctions/arch/AVX512/BesselFunctions.h
new file mode 100644
index 000000000..7dd3c3e5b
--- /dev/null
+++ b/unsupported/Eigen/src/SpecialFunctions/arch/AVX512/BesselFunctions.h
@@ -0,0 +1,46 @@
+#ifndef EIGEN_AVX512_BESSELFUNCTIONS_H
+#define EIGEN_AVX512_BESSELFUNCTIONS_H
+
+namespace Eigen {
+namespace internal {
+
+F16_PACKET_FUNCTION(Packet16f, Packet16h, pbessel_i0)
+BF16_PACKET_FUNCTION(Packet16f, Packet16bf, pbessel_i0)
+
+F16_PACKET_FUNCTION(Packet16f, Packet16h, pbessel_i0e)
+BF16_PACKET_FUNCTION(Packet16f, Packet16bf, pbessel_i0e)
+
+F16_PACKET_FUNCTION(Packet16f, Packet16h, pbessel_i1)
+BF16_PACKET_FUNCTION(Packet16f, Packet16bf, pbessel_i1)
+
+F16_PACKET_FUNCTION(Packet16f, Packet16h, pbessel_i1e)
+BF16_PACKET_FUNCTION(Packet16f, Packet16bf, pbessel_i1e)
+
+F16_PACKET_FUNCTION(Packet16f, Packet16h, pbessel_j0)
+BF16_PACKET_FUNCTION(Packet16f, Packet16bf, pbessel_j0)
+
+F16_PACKET_FUNCTION(Packet16f, Packet16h, pbessel_j1)
+BF16_PACKET_FUNCTION(Packet16f, Packet16bf, pbessel_j1)
+
+F16_PACKET_FUNCTION(Packet16f, Packet16h, pbessel_k0)
+BF16_PACKET_FUNCTION(Packet16f, Packet16bf, pbessel_k0)
+
+F16_PACKET_FUNCTION(Packet16f, Packet16h, pbessel_k0e)
+BF16_PACKET_FUNCTION(Packet16f, Packet16bf, pbessel_k0e)
+
+F16_PACKET_FUNCTION(Packet16f, Packet16h, pbessel_k1)
+BF16_PACKET_FUNCTION(Packet16f, Packet16bf, pbessel_k1)
+
+F16_PACKET_FUNCTION(Packet16f, Packet16h, pbessel_k1e)
+BF16_PACKET_FUNCTION(Packet16f, Packet16bf, pbessel_k1e)
+
+F16_PACKET_FUNCTION(Packet16f, Packet16h, pbessel_y0)
+BF16_PACKET_FUNCTION(Packet16f, Packet16bf, pbessel_y0)
+
+F16_PACKET_FUNCTION(Packet16f, Packet16h, pbessel_y1)
+BF16_PACKET_FUNCTION(Packet16f, Packet16bf, pbessel_y1)
+
+}  // namespace internal
+}  // namespace Eigen
+
+#endif  // EIGEN_AVX512_BESSELFUNCTIONS_H
diff --git a/unsupported/Eigen/src/SpecialFunctions/arch/AVX512/SpecialFunctions.h b/unsupported/Eigen/src/SpecialFunctions/arch/AVX512/SpecialFunctions.h
new file mode 100644
index 000000000..79878f2b6
--- /dev/null
+++ b/unsupported/Eigen/src/SpecialFunctions/arch/AVX512/SpecialFunctions.h
@@ -0,0 +1,16 @@
+#ifndef EIGEN_AVX512_SPECIALFUNCTIONS_H
+#define EIGEN_AVX512_SPECIALFUNCTIONS_H
+
+namespace Eigen {
+namespace internal {
+
+F16_PACKET_FUNCTION(Packet16f, Packet16h, perf)
+BF16_PACKET_FUNCTION(Packet16f, Packet16bf, perf)
+
+F16_PACKET_FUNCTION(Packet16f, Packet16h, pndtri)
+BF16_PACKET_FUNCTION(Packet16f, Packet16bf, pndtri)
+
+}  // namespace internal
+}  // namespace Eigen
+
+#endif  // EIGEN_AVX512_SPECIAL_FUNCTIONS_H
diff --git a/unsupported/Eigen/src/SpecialFunctions/arch/GPU/GpuSpecialFunctions.h b/unsupported/Eigen/src/SpecialFunctions/arch/GPU/SpecialFunctions.h
similarity index 100%
rename from unsupported/Eigen/src/SpecialFunctions/arch/GPU/GpuSpecialFunctions.h
rename to unsupported/Eigen/src/SpecialFunctions/arch/GPU/SpecialFunctions.h
diff --git a/unsupported/Eigen/src/SpecialFunctions/arch/NEON/BesselFunctions.h b/unsupported/Eigen/src/SpecialFunctions/arch/NEON/BesselFunctions.h
new file mode 100644
index 000000000..67433b057
--- /dev/null
+++ b/unsupported/Eigen/src/SpecialFunctions/arch/NEON/BesselFunctions.h
@@ -0,0 +1,54 @@
+#ifndef EIGEN_NEON_BESSELFUNCTIONS_H
+#define EIGEN_NEON_BESSELFUNCTIONS_H
+
+namespace Eigen {
+namespace internal {
+
+#if EIGEN_HAS_ARM64_FP16_VECTOR_ARITHMETIC
+
+#define NEON_HALF_TO_FLOAT_FUNCTIONS(METHOD)                            \
+template <> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE                       \
+Packet8hf METHOD<Packet8hf>(const Packet8hf& x) {                       \
+  const Packet4f lo = METHOD<Packet4f>(vcvt_f32_f16(vget_low_f16(x)));  \
+  const Packet4f hi = METHOD<Packet4f>(vcvt_f32_f16(vget_high_f16(x))); \
+  return vcombine_f16(vcvt_f16_f32(lo), vcvt_f16_f32(hi));              \
+}                                                                       \
+                                                                        \
+template <> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE                       \
+Packet4hf METHOD<Packet4hf>(const Packet4hf& x) {                       \
+  return vcvt_f16_f32(METHOD<Packet4f>(vcvt_f32_f16(x)));               \
+}
+
+NEON_HALF_TO_FLOAT_FUNCTIONS(pbessel_i0)
+NEON_HALF_TO_FLOAT_FUNCTIONS(pbessel_i0e)
+NEON_HALF_TO_FLOAT_FUNCTIONS(pbessel_i1)
+NEON_HALF_TO_FLOAT_FUNCTIONS(pbessel_i1e)
+NEON_HALF_TO_FLOAT_FUNCTIONS(pbessel_j0)
+NEON_HALF_TO_FLOAT_FUNCTIONS(pbessel_j1)
+NEON_HALF_TO_FLOAT_FUNCTIONS(pbessel_k0)
+NEON_HALF_TO_FLOAT_FUNCTIONS(pbessel_k0e)
+NEON_HALF_TO_FLOAT_FUNCTIONS(pbessel_k1)
+NEON_HALF_TO_FLOAT_FUNCTIONS(pbessel_k1e)
+NEON_HALF_TO_FLOAT_FUNCTIONS(pbessel_y0)
+NEON_HALF_TO_FLOAT_FUNCTIONS(pbessel_y1)
+
+#undef NEON_HALF_TO_FLOAT_FUNCTIONS
+#endif
+
+BF16_PACKET_FUNCTION(Packet4f, Packet4bf, pbessel_i0)
+BF16_PACKET_FUNCTION(Packet4f, Packet4bf, pbessel_i0e)
+BF16_PACKET_FUNCTION(Packet4f, Packet4bf, pbessel_i1)
+BF16_PACKET_FUNCTION(Packet4f, Packet4bf, pbessel_i1e)
+BF16_PACKET_FUNCTION(Packet4f, Packet4bf, pbessel_j0)
+BF16_PACKET_FUNCTION(Packet4f, Packet4bf, pbessel_j1)
+BF16_PACKET_FUNCTION(Packet4f, Packet4bf, pbessel_k0)
+BF16_PACKET_FUNCTION(Packet4f, Packet4bf, pbessel_k0e)
+BF16_PACKET_FUNCTION(Packet4f, Packet4bf, pbessel_k1)
+BF16_PACKET_FUNCTION(Packet4f, Packet4bf, pbessel_k1e)
+BF16_PACKET_FUNCTION(Packet4f, Packet4bf, pbessel_y0)
+BF16_PACKET_FUNCTION(Packet4f, Packet4bf, pbessel_y1)
+
+}  // namespace internal
+}  // namespace Eigen
+
+#endif  // EIGEN_NEON_BESSELFUNCTIONS_H
diff --git a/unsupported/Eigen/src/SpecialFunctions/arch/NEON/SpecialFunctions.h b/unsupported/Eigen/src/SpecialFunctions/arch/NEON/SpecialFunctions.h
new file mode 100644
index 000000000..f8dda28fc
--- /dev/null
+++ b/unsupported/Eigen/src/SpecialFunctions/arch/NEON/SpecialFunctions.h
@@ -0,0 +1,34 @@
+#ifndef EIGEN_NEON_SPECIALFUNCTIONS_H
+#define EIGEN_NEON_SPECIALFUNCTIONS_H
+
+namespace Eigen {
+namespace internal {
+
+#ifdef EIGEN_HAS_ARM64_FP16_VECTOR_ARITHMETIC
+
+#define NEON_HALF_TO_FLOAT_FUNCTIONS(METHOD)                            \
+template <> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE                       \
+Packet8hf METHOD<Packet8hf>(const Packet8hf& x) {                       \
+  const Packet4f lo = METHOD<Packet4f>(vcvt_f32_f16(vget_low_f16(x)));  \
+  const Packet4f hi = METHOD<Packet4f>(vcvt_f32_f16(vget_high_f16(x))); \
+  return vcombine_f16(vcvt_f16_f32(lo), vcvt_f16_f32(hi));              \
+}                                                                       \
+                                                                        \
+template <> EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE                       \
+Packet4hf METHOD<Packet4hf>(const Packet4hf& x) {                       \
+  return vcvt_f16_f32(METHOD<Packet4f>(vcvt_f32_f16(x)));               \
+}
+
+NEON_HALF_TO_FLOAT_FUNCTIONS(perf)
+NEON_HALF_TO_FLOAT_FUNCTIONS(pndtri)
+
+#undef NEON_HALF_TO_FLOAT_FUNCTIONS
+#endif
+
+BF16_PACKET_FUNCTION(Packet4f, Packet4bf, perf)
+BF16_PACKET_FUNCTION(Packet4f, Packet4bf, pndtri)
+
+}  // namespace internal
+}  // namespace Eigen
+
+#endif  // EIGEN_NEON_SPECIALFUNCTIONS_H
diff --git a/unsupported/test/special_functions.cpp b/unsupported/test/special_functions.cpp
index 1027272d5..56848daa5 100644
--- a/unsupported/test/special_functions.cpp
+++ b/unsupported/test/special_functions.cpp
@@ -11,6 +11,17 @@
 #include "main.h"
 #include "../Eigen/SpecialFunctions"
 
+// Hack to allow "implicit" conversions from double to Scalar via comma-initialization.
+template<typename Derived>
+Eigen::CommaInitializer<Derived> operator<<(Eigen::DenseBase<Derived>& dense, double v) {
+  return (dense << static_cast<typename Derived::Scalar>(v));
+}
+
+template<typename XprType>
+Eigen::CommaInitializer<XprType>& operator,(Eigen::CommaInitializer<XprType>& ci, double v) {
+  return (ci, static_cast<typename XprType::Scalar>(v));
+}
+
 template<typename X, typename Y>
 void verify_component_wise(const X& x, const Y& y)
 {
@@ -65,8 +76,8 @@ template<typename ArrayType> void array_special_functions()
       //   igamma(a, x) = gamma(a, x) / Gamma(a)
       // where Gamma and gamma are considered the standard unnormalized
       // upper and lower incomplete gamma functions, respectively.
-      ArrayType a = m1.abs() + 2;
-      ArrayType x = m2.abs() + 2;
+      ArrayType a = m1.abs() + Scalar(2);
+      ArrayType x = m2.abs() + Scalar(2);
       ArrayType zero = ArrayType::Zero(rows, cols);
       ArrayType one = ArrayType::Constant(rows, cols, Scalar(1.0));
       ArrayType a_m1 = a - one;
@@ -83,18 +94,18 @@ template<typename ArrayType> void array_special_functions()
       VERIFY_IS_APPROX(Gamma_a_x + gamma_a_x, a.lgamma().exp());
 
       // Gamma(a, x) == (a - 1) * Gamma(a-1, x) + x^(a-1) * exp(-x)
-      VERIFY_IS_APPROX(Gamma_a_x, (a - 1) * Gamma_a_m1_x + x.pow(a-1) * (-x).exp());
+      VERIFY_IS_APPROX(Gamma_a_x, (a - Scalar(1)) * Gamma_a_m1_x + x.pow(a-Scalar(1)) * (-x).exp());
 
       // gamma(a, x) == (a - 1) * gamma(a-1, x) - x^(a-1) * exp(-x)
-      VERIFY_IS_APPROX(gamma_a_x, (a - 1) * gamma_a_m1_x - x.pow(a-1) * (-x).exp());
+      VERIFY_IS_APPROX(gamma_a_x, (a - Scalar(1)) * gamma_a_m1_x - x.pow(a-Scalar(1)) * (-x).exp());
     }
     {
       // Verify for large a and x that values are between 0 and 1.
       ArrayType m1 = ArrayType::Random(rows,cols);
       ArrayType m2 = ArrayType::Random(rows,cols);
-      Scalar max_exponent = std::numeric_limits<Scalar>::max_exponent10;
-      ArrayType a = m1.abs() *  pow(10., max_exponent - 1);
-      ArrayType x = m2.abs() *  pow(10., max_exponent - 1);
+      int max_exponent = std::numeric_limits<Scalar>::max_exponent10;
+      ArrayType a = m1.abs() *  Scalar(pow(10., max_exponent - 1));
+      ArrayType x = m2.abs() *  Scalar(pow(10., max_exponent - 1));
       for (int i = 0; i < a.size(); ++i) {
         Scalar igam = numext::igamma(a(i), x(i));
         VERIFY(0 <= igam);
@@ -108,27 +119,37 @@ template<typename ArrayType> void array_special_functions()
       Scalar x_s[] = {Scalar(0), Scalar(1), Scalar(1.5), Scalar(4), Scalar(0.0001), Scalar(1000.5)};
 
       // location i*6+j corresponds to a_s[i], x_s[j].
-      Scalar igamma_s[][6] = {{0.0, nan, nan, nan, nan, nan},
-                              {0.0, 0.6321205588285578, 0.7768698398515702,
-                              0.9816843611112658, 9.999500016666262e-05, 1.0},
-                              {0.0, 0.4275932955291202, 0.608374823728911,
-                              0.9539882943107686, 7.522076445089201e-07, 1.0},
-                              {0.0, 0.01898815687615381, 0.06564245437845008,
-                              0.5665298796332909, 4.166333347221828e-18, 1.0},
-                              {0.0, 0.9999780593618628, 0.9999899967080838,
-                              0.9999996219837988, 0.9991370418689945, 1.0},
-                              {0.0, 0.0, 0.0, 0.0, 0.0, 0.5042041932513908}};
-      Scalar igammac_s[][6] = {{nan, nan, nan, nan, nan, nan},
-                              {1.0, 0.36787944117144233, 0.22313016014842982,
-                                0.018315638888734182, 0.9999000049998333, 0.0},
-                              {1.0, 0.5724067044708798, 0.3916251762710878,
-                                0.04601170568923136, 0.9999992477923555, 0.0},
-                              {1.0, 0.9810118431238462, 0.9343575456215499,
-                                0.4334701203667089, 1.0, 0.0},
-                              {1.0, 2.1940638138146658e-05, 1.0003291916285e-05,
-                                3.7801620118431334e-07, 0.0008629581310054535,
-                                0.0},
-                              {1.0, 1.0, 1.0, 1.0, 1.0, 0.49579580674813944}};
+      Scalar igamma_s[][6] = {
+          {Scalar(0.0), nan, nan, nan, nan, nan},
+          {Scalar(0.0), Scalar(0.6321205588285578), Scalar(0.7768698398515702),
+           Scalar(0.9816843611112658), Scalar(9.999500016666262e-05),
+           Scalar(1.0)},
+          {Scalar(0.0), Scalar(0.4275932955291202), Scalar(0.608374823728911),
+           Scalar(0.9539882943107686), Scalar(7.522076445089201e-07),
+           Scalar(1.0)},
+          {Scalar(0.0), Scalar(0.01898815687615381),
+           Scalar(0.06564245437845008), Scalar(0.5665298796332909),
+           Scalar(4.166333347221828e-18), Scalar(1.0)},
+          {Scalar(0.0), Scalar(0.9999780593618628), Scalar(0.9999899967080838),
+           Scalar(0.9999996219837988), Scalar(0.9991370418689945), Scalar(1.0)},
+          {Scalar(0.0), Scalar(0.0), Scalar(0.0), Scalar(0.0), Scalar(0.0),
+           Scalar(0.5042041932513908)}};
+      Scalar igammac_s[][6] = {
+          {nan, nan, nan, nan, nan, nan},
+          {Scalar(1.0), Scalar(0.36787944117144233),
+           Scalar(0.22313016014842982), Scalar(0.018315638888734182),
+           Scalar(0.9999000049998333), Scalar(0.0)},
+          {Scalar(1.0), Scalar(0.5724067044708798), Scalar(0.3916251762710878),
+           Scalar(0.04601170568923136), Scalar(0.9999992477923555),
+           Scalar(0.0)},
+          {Scalar(1.0), Scalar(0.9810118431238462), Scalar(0.9343575456215499),
+           Scalar(0.4334701203667089), Scalar(1.0), Scalar(0.0)},
+          {Scalar(1.0), Scalar(2.1940638138146658e-05),
+           Scalar(1.0003291916285e-05), Scalar(3.7801620118431334e-07),
+           Scalar(0.0008629581310054535), Scalar(0.0)},
+          {Scalar(1.0), Scalar(1.0), Scalar(1.0), Scalar(1.0), Scalar(1.0),
+           Scalar(0.49579580674813944)}};
+
       for (int i = 0; i < 6; ++i) {
         for (int j = 0; j < 6; ++j) {
           if ((std::isnan)(igamma_s[i][j])) {
@@ -162,8 +183,8 @@ template<typename ArrayType> void array_special_functions()
         ArrayType m1 = ArrayType::Random(32);
         using std::sqrt;
 
-        ArrayType cdf_val = (m1 / sqrt(2.)).erf();
-        cdf_val = (cdf_val + 1.) / 2.;
+        ArrayType cdf_val = (m1 / Scalar(sqrt(2.))).erf();
+        cdf_val = (cdf_val + Scalar(1)) / Scalar(2);
         verify_component_wise(cdf_val.ndtri(), m1););
 
   }
@@ -190,7 +211,6 @@ template<typename ArrayType> void array_special_functions()
     CALL_SUBTEST( res = digamma(x);  verify_component_wise(res, ref); );
   }
 
-
 #if EIGEN_HAS_C99_MATH
   {
     ArrayType n(11), x(11), res(11), ref(11);
@@ -323,8 +343,8 @@ template<typename ArrayType> void array_special_functions()
     ArrayType m3 = ArrayType::Random(32);
     ArrayType one = ArrayType::Constant(32, Scalar(1.0));
     const Scalar eps = std::numeric_limits<Scalar>::epsilon();
-    ArrayType a = (m1 * 4.0).exp();
-    ArrayType b = (m2 * 4.0).exp();
+    ArrayType a = (m1 * Scalar(4)).exp();
+    ArrayType b = (m2 * Scalar(4)).exp();
     ArrayType x = m3.abs();
 
     // betainc(a, 1, x) == x**a
@@ -471,4 +491,7 @@ EIGEN_DECLARE_TEST(special_functions)
 {
   CALL_SUBTEST_1(array_special_functions<ArrayXf>());
   CALL_SUBTEST_2(array_special_functions<ArrayXd>());
+  // TODO(cantonios): half/bfloat16 don't have enough precision to reproduce results above.
+  // CALL_SUBTEST_3(array_special_functions<ArrayX<Eigen::half>>());
+  // CALL_SUBTEST_4(array_special_functions<ArrayX<Eigen::bfloat16>>());
 }
diff --git a/unsupported/test/special_packetmath.cpp b/unsupported/test/special_packetmath.cpp
index 87b87351b..4f426eb8a 100644
--- a/unsupported/test/special_packetmath.cpp
+++ b/unsupported/test/special_packetmath.cpp
@@ -8,6 +8,7 @@
 // Public License v. 2.0. If a copy of the MPL was not distributed
 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+#include <limits>
 #include "packetmath_test_shared.h"
 #include "../Eigen/SpecialFunctions"
 
@@ -43,42 +44,48 @@ template<typename Scalar,typename Packet> void packetmath_real()
   }
   {
     for (int i=0; i<size; ++i) {
-      data1[i] = internal::random<Scalar>(0,1);
+      data1[i] = internal::random<Scalar>(Scalar(0),Scalar(1));
     }
     CHECK_CWISE1_IF(internal::packet_traits<Scalar>::HasNdtri, numext::ndtri, internal::pndtri);
   }
 #endif  // EIGEN_HAS_C99_MATH
 
   // For bessel_i*e and bessel_j*, the valid range is negative reals.
-  for (int i=0; i<size; ++i)
   {
-    data1[i] = internal::random<Scalar>(-1,1) * std::pow(Scalar(10), internal::random<Scalar>(-6,6));
-    data2[i] = internal::random<Scalar>(-1,1) * std::pow(Scalar(10), internal::random<Scalar>(-6,6));
-  }
+    const int max_exponent = numext::mini(std::numeric_limits<Scalar>::max_exponent10-1, 6);
+    for (int i=0; i<size; ++i)
+    {
+      data1[i] = internal::random<Scalar>(Scalar(-1),Scalar(1)) * Scalar(std::pow(Scalar(10), internal::random<Scalar>(Scalar(-max_exponent),Scalar(max_exponent))));
+      data2[i] = internal::random<Scalar>(Scalar(-1),Scalar(1)) * Scalar(std::pow(Scalar(10), internal::random<Scalar>(Scalar(-max_exponent),Scalar(max_exponent))));
+    }
 
-  CHECK_CWISE1_IF(PacketTraits::HasBessel, numext::bessel_i0e, internal::pbessel_i0e);
-  CHECK_CWISE1_IF(PacketTraits::HasBessel, numext::bessel_i1e, internal::pbessel_i1e);
-  CHECK_CWISE1_IF(PacketTraits::HasBessel, numext::bessel_j0, internal::pbessel_j0);
-  CHECK_CWISE1_IF(PacketTraits::HasBessel, numext::bessel_j1, internal::pbessel_j1);
+    CHECK_CWISE1_IF(PacketTraits::HasBessel, numext::bessel_i0e, internal::pbessel_i0e);
+    CHECK_CWISE1_IF(PacketTraits::HasBessel, numext::bessel_i1e, internal::pbessel_i1e);
+    CHECK_CWISE1_IF(PacketTraits::HasBessel, numext::bessel_j0, internal::pbessel_j0);
+    CHECK_CWISE1_IF(PacketTraits::HasBessel, numext::bessel_j1, internal::pbessel_j1);
+  }
 
   // Use a smaller data range for the bessel_i* as these can become very large.
   // Following #1693, we also restrict this range further to avoid inf's due to
   // differences in pexp and exp.
   for (int i=0; i<size; ++i) {
-      data1[i] = internal::random<Scalar>(0.01,1) * std::pow(
-          Scalar(9), internal::random<Scalar>(-1,2));
-      data2[i] = internal::random<Scalar>(0.01,1) * std::pow(
-          Scalar(9), internal::random<Scalar>(-1,2));
+      data1[i] = internal::random<Scalar>(Scalar(0.01),Scalar(1)) *
+                  Scalar(std::pow(Scalar(9), internal::random<Scalar>(Scalar(-1),Scalar(2))));
+      data2[i] = internal::random<Scalar>(Scalar(0.01),Scalar(1)) *
+                  Scalar(std::pow(Scalar(9), internal::random<Scalar>(Scalar(-1),Scalar(2))));
   }
   CHECK_CWISE1_IF(PacketTraits::HasBessel, numext::bessel_i0, internal::pbessel_i0);
   CHECK_CWISE1_IF(PacketTraits::HasBessel, numext::bessel_i1, internal::pbessel_i1);
 
 
   // y_i, and k_i are valid for x > 0.
-  for (int i=0; i<size; ++i)
   {
-    data1[i] = internal::random<Scalar>(0.01,1) * std::pow(Scalar(10), internal::random<Scalar>(-2,5));
-    data2[i] = internal::random<Scalar>(0.01,1) * std::pow(Scalar(10), internal::random<Scalar>(-2,5));
+    const int max_exponent = numext::mini(std::numeric_limits<Scalar>::max_exponent10-1, 5);
+    for (int i=0; i<size; ++i)
+    {
+      data1[i] = internal::random<Scalar>(Scalar(0.01),Scalar(1)) * Scalar(std::pow(Scalar(10), internal::random<Scalar>(Scalar(-2),Scalar(max_exponent))));
+      data2[i] = internal::random<Scalar>(Scalar(0.01),Scalar(1)) * Scalar(std::pow(Scalar(10), internal::random<Scalar>(Scalar(-2),Scalar(max_exponent))));
+    }
   }
 
   // TODO(srvasude): Re-enable this test once properly investigated why the
@@ -91,20 +98,20 @@ template<typename Scalar,typename Packet> void packetmath_real()
   // Following #1693, we restrict the range for exp to avoid zeroing out too
   // fast.
   for (int i=0; i<size; ++i) {
-      data1[i] = internal::random<Scalar>(0.01,1) * std::pow(
-          Scalar(9), internal::random<Scalar>(-1,2));
-      data2[i] = internal::random<Scalar>(0.01,1) * std::pow(
-          Scalar(9), internal::random<Scalar>(-1,2));
+      data1[i] = internal::random<Scalar>(Scalar(0.01),Scalar(1)) *
+                  Scalar(std::pow(Scalar(9), internal::random<Scalar>(Scalar(-1),Scalar(2))));
+      data2[i] = internal::random<Scalar>(Scalar(0.01),Scalar(1)) *
+                  Scalar(std::pow(Scalar(9), internal::random<Scalar>(Scalar(-1),Scalar(2))));
   }
   CHECK_CWISE1_IF(PacketTraits::HasBessel, numext::bessel_k0, internal::pbessel_k0);
   CHECK_CWISE1_IF(PacketTraits::HasBessel, numext::bessel_k1, internal::pbessel_k1);
 
 
   for (int i=0; i<size; ++i) {
-      data1[i] = internal::random<Scalar>(0.01,1) * std::pow(
-          Scalar(10), internal::random<Scalar>(-1,2));
-      data2[i] = internal::random<Scalar>(0.01,1) * std::pow(
-          Scalar(10), internal::random<Scalar>(-1,2));
+      data1[i] = internal::random<Scalar>(Scalar(0.01),Scalar(1)) *
+                  Scalar(std::pow(Scalar(10), internal::random<Scalar>(Scalar(-1),Scalar(2))));
+      data2[i] = internal::random<Scalar>(Scalar(0.01),Scalar(1)) *
+                  Scalar(std::pow(Scalar(10), internal::random<Scalar>(Scalar(-1),Scalar(2))));
   }
 
 #if EIGEN_HAS_C99_MATH && (__cplusplus > 199711L)
@@ -135,6 +142,8 @@ EIGEN_DECLARE_TEST(special_packetmath)
 
     CALL_SUBTEST_1( test::runner<float>::run() );
     CALL_SUBTEST_2( test::runner<double>::run() );
+    CALL_SUBTEST_3( test::runner<Eigen::half>::run() );
+    CALL_SUBTEST_4( test::runner<Eigen::bfloat16>::run() );
     g_first_pass = false;
   }
 }