From eda5bc26f44ee9a6f83dcf8c91f17296d7fc509d Mon Sep 17 00:00:00 2001
From: Nao Pross <np@0hm.ch>
Date: Mon, 12 Feb 2024 14:52:43 +0100
Subject: Move into version control

---
 .../include/armadillo_bits/op_roots_meat.hpp       | 140 +++++++++++++++++++++
 1 file changed, 140 insertions(+)
 create mode 100644 src/armadillo/include/armadillo_bits/op_roots_meat.hpp

(limited to 'src/armadillo/include/armadillo_bits/op_roots_meat.hpp')

diff --git a/src/armadillo/include/armadillo_bits/op_roots_meat.hpp b/src/armadillo/include/armadillo_bits/op_roots_meat.hpp
new file mode 100644
index 0000000..1e09120
--- /dev/null
+++ b/src/armadillo/include/armadillo_bits/op_roots_meat.hpp
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: Apache-2.0
+// 
+// Copyright 2008-2016 Conrad Sanderson (http://conradsanderson.id.au)
+// Copyright 2008-2016 National ICT Australia (NICTA)
+// 
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+// 
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// ------------------------------------------------------------------------
+
+
+//! \addtogroup op_roots
+//! @{
+
+
+
+template<typename T1>
+inline
+void
+op_roots::apply(Mat< std::complex<typename T1::pod_type> >& out, const mtOp<std::complex<typename T1::pod_type>, T1, op_roots>& expr)
+  {
+  arma_extra_debug_sigprint();
+  
+  const bool status = op_roots::apply_direct(out, expr.m);
+  
+  if(status == false)
+    {
+    out.soft_reset();
+    arma_stop_runtime_error("roots(): eigen decomposition failed");
+    }
+  }
+
+
+
+template<typename T1>
+inline
+bool
+op_roots::apply_direct(Mat< std::complex<typename T1::pod_type> >& out, const Base<typename T1::elem_type, T1>& X)
+  {
+  arma_extra_debug_sigprint();
+  
+  typedef std::complex<typename T1::pod_type> out_eT;
+  
+  const quasi_unwrap<T1> U(X.get_ref());
+  
+  bool status = false;
+  
+  if(U.is_alias(out))
+    {
+    Mat<out_eT> tmp;
+    
+    status = op_roots::apply_noalias(tmp, U.M);
+    
+    out.steal_mem(tmp);
+    }
+  else
+    {
+    status = op_roots::apply_noalias(out, U.M);
+    }
+  
+  return status;
+  }
+
+
+
+template<typename eT>
+inline
+bool
+op_roots::apply_noalias(Mat< std::complex<typename get_pod_type<eT>::result> >& out, const Mat<eT>& X)
+  {
+  arma_extra_debug_sigprint();
+  
+  typedef typename get_pod_type<eT>::result T;
+  
+  typedef std::complex<typename get_pod_type<eT>::result> out_eT;
+  
+  arma_debug_check( (X.is_vec() == false), "roots(): given object must be a vector" );
+  
+  if(X.internal_has_nonfinite())  { return false; }
+  
+  // treat X as a column vector
+  
+  const Col<eT> Y( const_cast<eT*>(X.memptr()), X.n_elem, false, false);
+  
+  const T Y_max = (Y.is_empty() == false) ? T(max(abs(Y))) : T(0);
+  
+  if(Y_max == T(0))  { out.set_size(1,0); return true; }
+  
+  const uvec indices = find( Y / Y_max );
+  
+  const uword n_tail_zeros = (indices.n_elem > 0) ? uword( (Y.n_elem-1) - indices[indices.n_elem-1] ) : uword(0);
+  
+  const Col<eT> Z = Y.subvec( indices[0], indices[indices.n_elem-1] );
+  
+  if(Z.n_elem >= uword(2))
+    {
+    Mat<eT> tmp;
+    
+    if(Z.n_elem == uword(2))
+      {
+      tmp.set_size(1,1);
+      
+      tmp[0] = -Z[1] / Z[0];
+      }
+    else
+      {
+      tmp = diagmat(ones< Col<eT> >(Z.n_elem - 2), -1);
+      
+      tmp.row(0) = strans(-Z.subvec(1, Z.n_elem-1) / Z[0]);
+      }
+    
+    Mat<out_eT> junk;
+    
+    const bool status = auxlib::eig_gen(out, junk, false, tmp);
+    
+    if(status == false)  { return false; }
+    
+    if(n_tail_zeros > 0)
+      {
+      out.resize(out.n_rows + n_tail_zeros, 1);
+      }
+    }
+  else
+    {
+    out.zeros(n_tail_zeros,1);
+    }
+  
+  return true;
+  }
+
+
+
+//! @}
-- 
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