molecule dna3( int numberOfBases, float roll, float tilt, float twist, float rise ){
	molecule mLastResidue, mres, m;
	residue res;
	int i;
	matrix rotationMatrix, riseMatrix;
	mLastResidue = NULL;

	rotationMatrix = newtransform( 0., 0., 0., roll, tilt, twist );	
	riseMatrix = newtransform( 0., 0., rise, 0., 0., 0. );

	res = getresidue( "3NA", "dna3.rlb" );

	m = newmolecule();
	addstrand( m, "1" );

	mres = newmolecule();
	addstrand( mres, "1" );
	addresidue( mres, "1", res );

	for ( i = 1; i <= numberOfBases; i++ ){
		alignframe( mres, mLastResidue );
		transformmol( rotationMatrix, mres, NULL );
		transformmol( riseMatrix, mres, NULL );
		mLastResidue = copymolecule( mres );
		setframe( 0, mLastResidue, "::CE", "::CE", "::SI", "::CE", "::MA" );
		mergestr( m, "1", "last", mres, "1", "first" );
		if ( i > 1 )
			connectres( m, "1", i-1, "CE", i, "CE" );
		mres = newmolecule();
		addstrand( mres, "1" );
		addresidue( mres, "1", res );
		setframe( 0, mres, "::CE", "::CE", "::SI", "::CE", "::MA" );
	}

	return( m );
};