Understand complicated algorithms

Code

for (arcp = memp->parents ; arcp ; arcp = arcp->arc_parentlist) {
    [...]
    if ( headp -> npropcall ) {
        headp -> propfraction += parentp -> propfraction
                * ( ( (double) arcp -> arc_count )
                  / ( (double) headp -> npropcall ) );
    }
}

Documentation

Algorithm Documentation