Hi @Miriam
You can pre assign the variables to empty or zeros before loop to save the values efficiently. I will make some modifications please check if it works.
a0, p and Zvs variables are changing every iteration
dt = [1:1:4];
Zvs = zeros(4,length(dt));
a0 = zeros(1,length(dt));
p = zeros(length(dt),5);
for i=1:length(dt)
a0(i)= 0.01*sqrt(d/D)*Fr/D*u*dt(i);
a1=0;
a2=7.07;
a3=4.45/tan(phi);
a4=0.786/(tan(phi)*tan(phi));
p(i,:)=[a4 a3 a2 a1 a0(i)];
Zvs(:,i)=real(roots(p(i,:)))*D;
end
