trsm.hpp

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//
// Copyright (c) 2017-2021, University of Tennessee. All rights reserved.
// Copyright (c) 2025, University of Colorado Denver. All rights reserved.
//
// This file is part of <T>LAPACK.
// <T>LAPACK is free software: you can redistribute it and/or modify it under
// the terms of the BSD 3-Clause license. See the accompanying LICENSE file.
 
#ifndef TLAPACK_LEGACY_TRSM_HH
#define TLAPACK_LEGACY_TRSM_HH
 
#include "tlapack/blas/trsm.hpp"
#include "tlapack/legacy_api/base/types.hpp"
#include "tlapack/legacy_api/base/utils.hpp"
 
namespace tlapack {
namespace legacy {
 
    template <typename TA, typename TB>
    void trsm(Layout layout,
              Side side,
              Uplo uplo,
              Op trans,
              Diag diag,
              idx_t m,
              idx_t n,
              scalar_type<TA, TB> alpha,
              TA const* A,
              idx_t lda,
              TB* B,
              idx_t ldb)
    {
        using internal::create_matrix;
        using scalar_t = scalar_type<TA, TB>;
 
        // check arguments
        tlapack_check_false(layout != Layout::ColMajor &&
                            layout != Layout::RowMajor);
        tlapack_check_false(side != Side::Left && side != Side::Right);
        tlapack_check_false(uplo != Uplo::Lower && uplo != Uplo::Upper);
        tlapack_check_false(trans != Op::NoTrans && trans != Op::Trans &&
                            trans != Op::ConjTrans);
        tlapack_check_false(diag != Diag::NonUnit && diag != Diag::Unit);
        tlapack_check_false(m < 0);
        tlapack_check_false(n < 0);
        tlapack_check_false(lda < ((side == Side::Left) ? m : n));
        tlapack_check_false(ldb < ((layout == Layout::RowMajor) ? n : m));
 
        // quick return
        if (m == 0 || n == 0) return;
 
        // adapt if row major
        if (layout == Layout::RowMajor) {
            side = (side == Side::Left) ? Side::Right : Side::Left;
            if (uplo == Uplo::Lower)
                uplo = Uplo::Upper;
            else if (uplo == Uplo::Upper)
                uplo = Uplo::Lower;
            std::swap(m, n);
        }
 
        // Matrix views
        const auto A_ = (side == Side::Left)
                            ? create_matrix<TA>((TA*)A, m, m, lda)
                            : create_matrix<TA>((TA*)A, n, n, lda);
        auto B_ = create_matrix<TB>(B, m, n, ldb);
 
        if (alpha == scalar_t(0))
            for (idx_t j = 0; j < n; ++j)
                for (idx_t i = 0; i < m; ++i)
                    B_(i, j) = TB(0);
        else
            trsm(side, uplo, trans, diag, alpha, A_, B_);
    }
 
}  // namespace legacy
}  // namespace tlapack
 
#endif  //  #ifndef TLAPACK_LEGACY_TRSM_HH