Theoretical and Experimental DNA Computation (Natural ...

104 4 Complexity Issues
10. LDC 0
11. STA 2n + k /* distance(k) :=0
12. HALT
(Note that the memory addresses given translate to fixed values for a fixed n
and processor identifier k).
The second (block of) m instructions follows:
for all k ∈ L in parallel do
if P (k) �= P (P (k)) then
begin
distance(k) :=distance(k)+distance(P (k));
P (k) :=P (P (k));
end;
1. LDC n /* Base for P (k)
2. ADD n + k /* n + P (k), i.e. address of P (P (k))
3. STA 3n + k
4. LDI 3n + k /* P (P (k))
5. SUB n + k
6. STA 3n + k
7. JEQ 3n + k, 19 /* P (k) �= P (P (k))
8. LDC 2n /* Base for distance(k)
9. ADD n + k /* 2n + P (k), i.e. address of distance(P (k))
10. STA 3n + k
11. LDI 3n + k
12. ADD 2n + k /* distance(P (k)) + distance(k)
13. STA 2n + k /* distance(k) :=distance(k)+distance(P (k))
14. LDC n /* Base for P (k)
15. ADD n + k /* n + P (k), i.e. address of P (P (k))
16. STA 3n + k
17. LDI 3n + k
18. STA n + k /* P (k) :=P (P (k))
19. HALT
Finally,
for all k ∈ L in parallel do
rank(k) :=distance(k);