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quadadd.c
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Sun, Jul 13, 02:53

quadadd.c
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/*
% [zhi,zlo] = quadadd(xhi,xlo,y)
% QUADADD Compute (zhi+zlo) = (xhi+xlo) + y.
% x an z are in double-double format (quad precision)
%
% SEE ALSO sedumi
% ********** INTERNAL FUNCTION OF SEDUMI **********
function [zhi,zlo] = quadadd(xhi,xlo,y)
% This file is part of SeDuMi 1.1 by Imre Polik and Oleksandr Romanko
% Copyright (C) 2005 McMaster University, Hamilton, CANADA (since 1.1)
%
% Copyright (C) 2001 Jos F. Sturm (up to 1.05R5)
% Dept. Econometrics & O.R., Tilburg University, the Netherlands.
% Supported by the Netherlands Organization for Scientific Research (NWO).
%
% Affiliation SeDuMi 1.03 and 1.04Beta (2000):
% 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., 51 Franklin Street, Fifth Floor, Boston, MA
% 02110-1301, USA
*/
#include <math.h>
#include "mex.h"
#include "blksdp.h"
#include <string.h>
#define ZHI_OUT myplhs[0]
#define ZLO_OUT myplhs[1]
#define NPAROUT 2
#define XHI_IN prhs[0]
#define XLO_IN prhs[1]
#define Y_IN prhs[2]
#define NPARIN 3
/* ************************************************************
PROCEDURE quadadd
RETURNS zhi.
************************************************************ */
double rquaddadd(double *pzlo, double xhi,double xlo, const double y)
{
double zhi, zlo;
/* ------------------------------------------------------------
|y| > |xhi| > |xlo|: Then fl(y+xlo) = y, thus add immediately to xhi.
------------------------------------------------------------ */
if(fabs(y) > fabs(xhi)){
zhi = y + xhi;
xhi -= (zhi-y); /* Residual xhi := xhi - fl((xhi+y)-y) */
*pzlo = xlo + xhi;
return zhi;
}
/* ------------------------------------------------------------
|xhi| > |y| > |xlo| or |xhi| > |xlo| > |y|
------------------------------------------------------------ */
else{
zlo = xlo + y;
xlo -= (zlo - y); /* If |xlo| > |y| then xlo := 0, otherwise resid. */
zhi = (xhi + zlo);
zlo -= (zhi - xhi); /* resid. */
*pzlo = xlo + zlo; /* If |xlo| > |y| then zlo, which lost y-digits */
}
return zhi;
}
/* ============================================================
MEXFUNCTION
============================================================ */
/* ************************************************************
PROCEDURE mexFunction - Entry for Matlab
************************************************************ */
void mexFunction(const int nlhs, mxArray *plhs[],
const int nrhs, const mxArray *prhs[])
{
mxArray *myplhs[NPAROUT];
mwSize m;
mwIndex i;
const double *xhi, *xlo, *y;
double *zhi, *zlo;
/* ------------------------------------------------------------
Check for proper number of arguments
------------------------------------------------------------ */
mxAssert(nrhs >= NPARIN, "quadadd requires more input arguments.");
mxAssert(nlhs <= NPAROUT, "quadadd produces less output arguments.");
/* ------------------------------------------------------------
Get input vectors xhi,xlo,y.
------------------------------------------------------------ */
m = mxGetM(XHI_IN);
mxAssert(mxGetM(XLO_IN) == m, "xlo size mismatch.");
mxAssert(mxGetM(Y_IN) == m, "y size mismatch.");
xhi = mxGetPr(XHI_IN);
xlo = mxGetPr(XLO_IN);
y = mxGetPr(Y_IN);
/* ------------------------------------------------------------
Create output vectors zhi(m), zlo(m).
------------------------------------------------------------ */
ZHI_OUT = mxCreateDoubleMatrix(m,(mwSize)1,mxREAL);
ZLO_OUT = mxCreateDoubleMatrix(m,(mwSize)1,mxREAL);
zhi = mxGetPr(ZHI_OUT);
zlo = mxGetPr(ZLO_OUT);
/* ------------------------------------------------------------
Let (zhi,zlo) = quadadd(xhi,xlo, y)
------------------------------------------------------------ */
for(i = 0; i < m; i++)
zhi[i] = rquaddadd(zlo+i, xhi[i],xlo[i],y[i]);
/* ------------------------------------------------------------
Copy requested output parameters (at least 1), release others.
------------------------------------------------------------ */
i = MAX(nlhs, 1);
memcpy(plhs,myplhs, i * sizeof(mxArray *));
for(; i < NPAROUT; i++)
mxDestroyArray(myplhs[i]);
}

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