syr2.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_SYR2_HH
#define TLAPACK_LEGACY_SYR2_HH
 
#include "tlapack/blas/syr2.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 syr2(Layout layout,
              Uplo uplo,
              idx_t n,
              scalar_type<TA, TX, TY> alpha,
              TX const* x,
              int_t incx,
              TY const* y,
              int_t incy,
              TA* A,
              idx_t lda)
    {
        using internal::create_matrix;
        using scalar_t = scalar_type<TA, TX>;
 
        // 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(incx == 0);
        tlapack_check_false(incy == 0);
        tlapack_check_false(lda < n);
 
        // quick return
        if (n == 0 || alpha == scalar_t(0)) return;
 
        // for row major, swap lower <=> upper
        if (layout == Layout::RowMajor) {
            uplo = (uplo == Uplo::Lower ? Uplo::Upper : Uplo::Lower);
        }
 
        // Matrix views
        auto A_ = create_matrix<TA>(A, n, n, lda);
 
        tlapack_expr_with_2vectors(x_, TX, n, x, incx, y_, TY, n, y, incy,
                                   return syr2(uplo, alpha, x_, y_, A_));
    }
 
}  // namespace legacy
}  // namespace tlapack
 
#endif  //  #ifndef TLAPACK_LEGACY_SYR2_HH