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armadillo-code/include/armadillo_bits/spop_strans_meat.hpp
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2020-10-20 18:40:30 +10:00

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// 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 spop_strans
//! @{
template<typename eT>
inline
void
spop_strans::apply_noalias(SpMat<eT>& B, const SpMat<eT>& A)
{
arma_extra_debug_sigprint();
B.reserve(A.n_cols, A.n_rows, A.n_nonzero); // deliberately swapped
if(A.n_nonzero == 0) { return; }
// This follows the TRANSP algorithm described in
// 'Sparse Matrix Multiplication Package (SMMP)'
// (R.E. Bank and C.C. Douglas, 2001)
const uword m = A.n_rows;
const uword n = A.n_cols;
const eT* a = A.values;
eT* b = access::rwp(B.values);
const uword* ia = A.col_ptrs;
const uword* ja = A.row_indices;
uword* ib = access::rwp(B.col_ptrs);
uword* jb = access::rwp(B.row_indices);
// // ib is already zeroed, as B is freshly constructed
//
// for(uword i=0; i < (m+1); ++i)
// {
// ib[i] = 0;
// }
for(uword i=0; i < n; ++i)
{
for(uword j = ia[i]; j < ia[i+1]; ++j)
{
ib[ ja[j] + 1 ]++;
}
}
for(uword i=0; i < m; ++i)
{
ib[i+1] += ib[i];
}
for(uword i=0; i < n; ++i)
{
for(uword j = ia[i]; j < ia[i+1]; ++j)
{
const uword jj = ja[j];
const uword ib_jj = ib[jj];
jb[ib_jj] = i;
b[ib_jj] = a[j];
ib[jj]++;
}
}
for(uword i = m-1; i >= 1; --i)
{
ib[i] = ib[i-1];
}
ib[0] = 0;
}
template<typename T1>
inline
void
spop_strans::apply(SpMat<typename T1::elem_type>& out, const SpOp<T1,spop_strans>& in)
{
arma_extra_debug_sigprint();
typedef typename T1::elem_type eT;
const unwrap_spmat<T1> U(in.m);
if(U.is_alias(out))
{
SpMat<eT> tmp;
spop_strans::apply_noalias(tmp, U.M);
out.steal_mem(tmp);
}
else
{
spop_strans::apply_noalias(out, U.M);
}
}
//! for transpose of non-complex matrices, redirected from spop_htrans::apply()
template<typename T1>
inline
void
spop_strans::apply(SpMat<typename T1::elem_type>& out, const SpOp<T1,spop_htrans>& in)
{
arma_extra_debug_sigprint();
typedef typename T1::elem_type eT;
const unwrap_spmat<T1> U(in.m);
if(U.is_alias(out))
{
SpMat<eT> tmp;
spop_strans::apply_noalias(tmp, U.M);
out.steal_mem(tmp);
}
else
{
spop_strans::apply_noalias(out, U.M);
}
}
//! @}