Checking for equilibrium
if ( checkEquilibrium ( $ x1 , $ y1 , $ z1 , $ x2 , $ y2 , $ z2 , $ x3 , $ y3 , $ z3 ) ) echo " The ▁ vectors ▁ are ▁ at ▁ equilibrium . " ; else echo " The ▁ vectors ▁ are ▁ not ▁ at ▁ equilibrium . " ; ? >