int		swap_shifts( float obs[ hashed ], float calc[ hashed ])
{

int		nswaps;
string	idp, idp2;
string	f[ 3 ];
float	temp;


nswaps = 0;
//
//  filter to swap the "observed" shifts of non-stereo assigned protons
//   to best match the calculated shifts
//
//
for( idp in obs ){

	split( idp, f, ":" );
	idp2 = "";

	if( f[3]=="HB3"  && f[1]!="ALA" ) idp2 = f[1] + ":" + f[2] + ":HB2";
	if( f[3]=="HG3" )                 idp2 = f[1] + ":" + f[2] + ":HG2";
	if( f[3]=="HD3"  && f[1]!="ILE" ) idp2 = f[1] + ":" + f[2] + ":HD2";
	if( f[3]=="HE3"  && f[1]=="LYS" ) idp2 = f[1] + ":" + f[2] + ":HE2";
	if( f[3]=="HG13" && f[1]=="ILE" ) idp2 = f[1] + ":" + f[2] + ":HG12";
	if( f[3]=="HG23" && f[1]=="VAL" ) idp2 = f[1] + ":" + f[2] + ":HG13";
	if( f[3]=="HD23" && f[1]=="LEU" ) idp2 = f[1] + ":" + f[2] + ":HD13";

	if( idp2 != "" ){
		if ((obs[idp]-obs[idp2])*(calc[idp]-calc[idp2]) < 0.0) {
			fprintf( stderr, "swapping %-13s %7.3f with %-13s %7.3f\n",
				idp, obs[idp], idp2, obs[idp2] );
			temp=obs[idp]; obs[idp]=obs[idp2]; obs[idp2]=temp;
			nswaps = nswaps + 1;
		}
	}
}
return( nswaps );
};