Performance Model of ZPL

Drainage (continued)

procedure drainage();

[R] begin

• Up := 0; Dn := 0;

read(A);

• Up := A=(min<<A);

• Dn := A=(max<<A);

repeat

• Tu := Up; Td := Dn;

Dn := Dn | (A<=A@no & Dn@no) | (A<=Ane & Dn@ne)

| (A<=A@ea & Dn@ea) | (A<=Ase & Dn@se)

• | (A<=A@so & Dn@so) | (A<=Asw & Dn@sw)

| (A<=A@we & Dn@we) | (A<=Anw & Dn@nw);

Up := Up | (A>=A@no & Up@no) | (A>=Ane & Up@ne)

• | (A>=A@ea & Up@ea) | (A>=Ase & Up@se)

| (A>=A@so & Up@so) | (A>=Asw & Up@sw)

• | (A>=A@we & Up@we) | (A>=Anw & Up@nw);

• until ! |<<((Tu != Up) | (Td != Dn));

write(Up&Dn);

• end;

Moving up

Moving down

Boundaries not included