for i:=1 to n do
     begin
      Y[i]:=(D1*Y[i-1])+(D2*X[i])+D3*Z[i];
      Z[i]:=(Z[i-1]*D4)+(D5*Y[i]);
     end;

for i:=0 to n do
 begin
   Y[i]:=0;
   Z[i]:=0;
 end
for i:=1 to n do
 begin
  Y[i]:=(D1*Y[i-1])+(D2*X[i])+D3*Z[i];
  Z[i]:=(Z[i-1]*D4)+(D5*Y[i]);
 end;