place-holder implementation of specialised accu() for fp16

include/armadillo_bits/fn_accu.hpp

@@ -31,7 +31,9 @@ accu(const T1& expr, const typename enable_if< is_arma_type<T1>::value >::result
   
   arma_ignore(junk);
   
-  return op_accu_mat::apply(expr);
+  typedef typename T1::elem_type eT;
+  
+  return (is_fp16<eT>::yes || is_cx_fp16<eT>::yes) ? op_accu_fp16mat::apply(expr) : op_accu_mat::apply(expr);
   }
 
 

include/armadillo_bits/op_accu_bones.hpp

@@ -69,6 +69,15 @@ struct  op_accu_mat
 
 
 
+struct  op_accu_fp16mat
+  : public traits_op_passthru
+  {
+  template<typename T1>
+  static inline typename T1::elem_type apply(const T1& X);
+  };
+
+
+
 struct  op_accu_cube
   : public traits_op_passthru
   {

include/armadillo_bits/op_accu_meat.hpp

@@ -654,6 +654,37 @@ op_accu_mat::apply(const subview_col<eT>& X)
 
 
 
+template<typename T1>
+inline
+typename T1::elem_type
+op_accu_fp16mat::apply(const T1& X)
+  {
+  arma_debug_sigprint();
+  
+  // TODO: this is a rudimentary place-holder implementation
+  
+  typedef typename T1::elem_type eT;
+  
+  typedef typename conditional_promote_type<is_real_or_cx<eT>::value, eT, float>::result acc_eT;
+  
+  const quasi_unwrap<T1> U(X);
+  
+  const uword N   = U.M.n_elem;
+  const eT*   mem = U.M.memptr();
+  
+  acc_eT acc = acc_eT(0);
+  
+  for(uword i=0; i<N; ++i)  { acc += acc_eT( mem[i] ); }
+  
+  return eT(acc);
+  }
+
+
+
+//
+
+
+
 template<typename T1>
 inline
 typename T1::elem_type