symv.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_SYMV_HH
#define TLAPACK_LEGACY_SYMV_HH
 
#include "tlapack/blas/symv.hpp"
#include "tlapack/legacy_api/base/types.hpp"
#include "tlapack/legacy_api/base/utils.hpp"
 
namespace tlapack {
namespace legacy {
 
    template <typename TA, typename TX, typename TY>
    void symv(Layout layout,
              Uplo uplo,
              idx_t n,
              scalar_type<TA, TX, TY> alpha,
              TA const* A,
              idx_t lda,
              TX const* x,
              int_t incx,
              scalar_type<TA, TX, TY> beta,
              TY* y,
              int_t incy)
    {
        using internal::create_matrix;
        using scalar_t = scalar_type<TA, TX, TY>;
 
        // check arguments
        tlapack_check_false(layout != Layout::ColMajor &&
                            layout != Layout::RowMajor);
        tlapack_check_false(uplo != Uplo::Lower && uplo != Uplo::Upper);
        tlapack_check_false(n < 0);
        tlapack_check_false(lda < n);
        tlapack_check_false(incx == 0);
        tlapack_check_false(incy == 0);
 
        // quick return
        if (n == 0 || ((alpha == scalar_t(0)) && (beta == scalar_t(1)))) return;
 
        // for row major, swap lower <=> upper
        if (layout == Layout::RowMajor) {
            uplo = (uplo == Uplo::Lower ? Uplo::Upper : Uplo::Lower);
        }
 
        // Views
        const auto A_ = create_matrix<TA>((TA*)A, n, n, lda);
 
        if (alpha == scalar_t(0)) {
            tlapack_expr_with_vector(
                y_, TY, n, y, incy,
                if (beta == scalar_t(0)) for (idx_t i = 0; i < n; ++i) y_[i] =
                    TY(0);
                else for (idx_t i = 0; i < n; ++i) y_[i] *= beta);
        }
        else {
            tlapack_expr_with_2vectors(
                x_, TX, n, x, incx, y_, TY, n, y, incy,
                if (beta == scalar_t(0)) return symv(uplo, alpha, A_, x_, y_);
                else return symv(uplo, alpha, A_, x_, beta, y_));
        }
    }
 
}  // namespace legacy
}  // namespace tlapack
 
#endif  //  #ifndef TLAPACK_LEGACY_SYMV_HH