private void permutePivot ( IntIntPair pos1 , IntIntPair pos2 ) { int r1 = pos1 . first ; int c1 = pos1 . second ; int r2 = pos2 . first ; int c2 = pos2 . second ; int index ; index = row [ r2 ] ; row [ r2 ] = row [ r1 ] ; row [ r1 ] = index ; index = col [ c2 ] ; col [ c2 ] = col [ c1 ] ; col [ c1 ] = index ; }
permutes two matrix rows and two matrix columns