/* ************************************************************
   MODULE sdmaux*.c  -- Several low-level subroutines for the
   mex-files in the Self-Dual-Minimization package.

    This file is part of SeDuMi 1.04BETA
    Copyright (C) 2000 Jos F. Sturm
    Dept. Quantitative Economics, Maastricht University, the Netherlands.
    Affiliations up to SeDuMi 1.02 (AUG1998):
      CRL, McMaster University, Canada.
      Supported by the Netherlands Organization for Scientific Research (NWO).
  
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
  
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
  
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   ************************************************************ */

#include <string.h>
#include "blksdp.h"
/* ************************************************************
   PROCEDURE: triudotprod - Computes trace(X*Y), where X and Y are
     supposed to be symmetric; only the triu's are used.
   INPUT
     x - full n x n, only triu(x) used
     y - full n x n, only triu(x) used
     n - order
   RETURNS the inner product between X and Y, trace(X*Y).
   ************************************************************ */
double triudotprod(const double *x, const double *y, const int n)
{
  int i, j;
  double z;
  if(n <= 0)
    return 0.0;
  z = x[0] * y[0];
  for(j = 1; j < n; j++){
    x += n; y += n;                  /* point to x(:,j) and y(:,j) */
    z += 2 * realdot(x,y,j) + x[j] * y[j];
  }
  return z;
}

/* striudotprod: z = tr(X*Y), where diag(X)=0. only triu(X,1) and triu(Y,1)
   are used. For the imaginary part into the real inner product. */
double striudotprod(const double *x, const double *y, const int n)
{
  int i, j;
  double z;
  if(n <= 1)
    return 0.0;
  z = 0.0;
  for(j = 1; j < n; j++){
    x += n; y += n;                  /* point to x(:,j) and y(:,j) */
    z += realdot(x,y,j);
  }
  return 2 * z;
}
