SUB Metropolis(x,delta,naccept)
    DECLARE DEF p
    LET xtrial = x + delta*(2*rnd - 1)
    LET w = p(xtrial)/p(x)
    IF rnd <= w then
       LET x = xtrial
       LET naccept = naccept + 1  ! number of acceptances
    END IF
END SUB