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/*****************************************************************************
* *
* Small (Matlab/Octave) Toolbox for Kriging *
* *
* Copyright Notice *
* *
* Copyright (C) 2015 CentraleSupelec *
* Copyright (C) 2011, 2012 SUPELEC *
* *
* Authors: Julien Bect <julien.bect@centralesupelec.fr> *
* Emmanuel Vazquez <emmanuel.vazquez@centralesupelec.fr> *
* *
* Copying Permission Statement *
* *
* This file is part of *
* *
* STK: a Small (Matlab/Octave) Toolbox for Kriging *
* (http://sourceforge.net/projects/kriging) *
* *
* STK 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 3 of the License, or (at your *
* option) any later version. *
* *
* STK 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 STK. If not, see <http://www.gnu.org/licenses/>. *
* *
****************************************************************************/
#include "stk_mex.h"
static void distance1(double* x, double* h, size_t nx, size_t dim)
{
size_t i, j, k1, k2;
double diff, lambda;
for (i = 0; i < nx; i++) {
/* put a zero on the diagonal */
h[i*(nx+1)] = 0.0;
for (j = i+1; j < nx; j++) {
/* compute distance between x[i,:] and x[j,:] */
lambda = 0.0;
for (k1 = i, k2 = j; k1 < dim * nx; k1 += nx, k2 += nx)
{
diff = x[k1] - x[k2];
lambda += diff * diff;
}
/* store the result in h, twice for symmetry */
h[i+nx*j] = sqrt(lambda);
h[j+nx*i] = h[i+nx*j];
}
}
}
mxArray* compute_distance_xx(const mxArray* x)
{
size_t d, n;
mxArray* h;
if(!stk_is_realmatrix(x))
mexErrMsgTxt("The input should be a real-valued double-precision array.");
/* Read the size of the input argument */
n = mxGetM(x);
d = mxGetN(x);
/* Create a matrix for the return argument */
h = mxCreateDoubleMatrix(n, n, mxREAL);
/* Do the actual computations in a subroutine */
distance1(mxGetPr(x), mxGetPr(h), n, d);
return h;
}
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray*prhs[])
{
if (nlhs > 1) /* Check number of output arguments */
mexErrMsgTxt("Too many output arguments.");
if (nrhs != 1) /* Check number of input arguments */
mexErrMsgTxt("Incorrect number of input arguments.");
plhs[0] = compute_distance_xx(prhs[0]);
}
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