subroutine diag( conj, add, lambda,n,  pp,    qq)
integer i,       conj, add,        n 		      # equivalence (pp,qq) OK
real 			    lambda(n), pp(n), qq(n)
if( conj == 0 ) {
	if( add == 0 ) { do i=1,n {  qq(i) =         lambda(i) * pp(i) } }
	else           { do i=1,n {  qq(i) = qq(i) + lambda(i) * pp(i) } }
	}
else {  if( add == 0 ) { do i=1,n {  pp(i) =         lambda(i) * qq(i) } }
	else           { do i=1,n {  pp(i) = pp(i) + lambda(i) * qq(i) } }
	}
return; end