mx_sequency_perm.cpp

//================================================
// @title        mx_sequency_perm.cpp
// @author       Jonathan Hadida
// @contact      Jonathan.hadida [at] dtc.ox.ac.uk
//================================================

#include "fwht.h"
#include "mexArray.h"
#include <algorithm>



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/**
 * Returns the sequency permutation (bitrev of Gray code) of order n.
 * Use the script start_matlab.sh to start Matlab, and compile with:
 * mex CXXFLAGS="\$CXXFLAGS -std=c++0x -Wall -O2" mx_sequency_perm.cpp
 */
void mexFunction(	int nargout, mxArray *out[],
					int nargin, const mxArray *in[] )
{
	if ( nargin != 1 )
	{		
		mexErrMsgTxt("Usage: p = mx_sequency_perm(order);");
		return;
	}

	ndArray<unsigned,2> output;

	unsigned n = static_cast<unsigned>(mxGetScalar(in[0]));
	std::vector<unsigned> p;
	fwht_sequency_permutation( p, n );

	int size[2];
		size[0] = 1;
		size[1] = p.size();
	out[0] = mxCreateNumericArray( 2, size, mx_type<unsigned>::id, mxREAL );
	output.assign( out[0] );

	std::copy( p.begin(), p.end(), output.begin() );
}