How can I make a constraint of particular value in if statement?

Hi I have a problem about making a constraint of the b in the if statement.

Here is my code:

Q=rawdata(:,1)*0.001;
days=rawdata(:,2);
t=(1:3240)';
a=0.925;
q=zeros(size(Q));
b=zeros(size(Q));

for i=2:length(t)
  if (q(i)>=0 && q(i)<=Q(i))

      q(i)=a*q(i-1)+((1+a)/2)*abs((Q(i)-Q(i-1)));   
    end
    if(b(i)>=0 && b(i) <=Q(i))
        b(i)=Q(i)-q(i);
    end
  end

I have tried this loop several times, but the b value is always negative.

Could someone help me to make a constraint of the b, which should be greater than zero?

Thanks!

Answer 1

[Image Analyst]

You mean like adding this at the end of your loop?

if b(i) < 0
  b(i) = 0;
end

or this:

b(i)=max([0, Q(i)-q(i)]);