Optimize an if loop

Good night people,

I have a question regarding the optimization of the following loop:

for i=1:length(PV)
        if i>3
       if NL(i-1)<=100
           if NL(i-2)<=100
               if NL(i-3)<=100
        u(i)=1;
       else
           u(i)=0;
       end
           end
       end
        end
end

I would like to reduce the if statements.

Thanks for your time,

Answer 1

[Matt J]

t=double(NL(:).'<=100);
u=(movsum(t,[3,0])-t)>=3;

[Ricardo López]

What should I do if I want to add more conditions, like in my example? And stored them in a u=zero(1,length(PV))

Thank you for your time

Answer 2

[Matt J]

u=[0,0,0,  conv(double(NL(:).'<=100),[1,1,1],'valid')>=3];