// Ceres Solver - A fast non-linear least squares minimizer

// Copyright 2015 Google Inc. All rights reserved.

// http://ceres-solver.org/

//

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are met:

//

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//   this list of conditions and the following disclaimer.

// * Redistributions in binary form must reproduce the above copyright notice,

//   this list of conditions and the following disclaimer in the documentation

//   and/or other materials provided with the distribution.

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//   used to endorse or promote products derived from this software without

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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

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// Author: sameeragarwal@google.com (Sameer Agarwal)

#include "ceres/blas.h"

#include "ceres/internal/port.h"

#include "glog/logging.h"

#ifndef CERES_NO_LAPACK

extern "C" void dsyrk_(char* uplo,

                       char* trans,

                       int* n,

                       int* k,

                       double* alpha,

                       double* a,

                       int* lda,

                       double* beta,

                       double* c,

                       int* ldc);

#endif

namespace ceres {

namespace internal {

void BLAS::SymmetricRankKUpdate(int num_rows,

                                int num_cols,

                                const double* a,

                                bool transpose,

                                double alpha,

                                double beta,

                                double* c) {

#ifdef CERES_NO_LAPACK

  LOG(FATAL) << "Ceres was built without a BLAS library.";

#else

  char uplo = 'L';

  char trans = transpose ? 'T' : 'N';

  int n = transpose ? num_cols : num_rows;

  int k = transpose ? num_rows : num_cols;

  int lda = k;

  int ldc = n;

  dsyrk_(&uplo,

         &trans,

         &n,

         &k,

         &alpha,

         const_cast<double*>(a),

         &lda,

         &beta,

         c,

         &ldc);

#endif

}

}  // namespace internal

}  // namespace ceres