how to change value of a parameter inside a for loop

Hi everyone this is my code clear all

a1 = 1; 
a2 = 1;
a3 = 1;
b1=1;
b2=1;
b3=1;
alpha = 1.2; 
F1 = 200; 
F2 = 3;
M=0.8;

dt=0.01;       % step size 
t=0:dt:10;  % time vector 

W1_new = zeros(length(t),1);
W2_new = zeros(length(t),1); 
W3_new = zeros(length(t),1);
f = zeros(length(t),1);

% Initial conditions for W1 and W2 given that W1 + W2 + W3 = 6
W1_new(1,1) = 1; 
W2_new(1,1) = 2;
W3_new(1,1) = 3;

for i=1:length(t)-1 

      W1_new1 = W1_new(i,1) + dt*((a1*W1_new(i,1)^alpha - F1*W1_new(i,1))*W1_new(i,1)+b1*(M-W1_new(i,1))); 
      W2_new1 = W2_new(i,1) + dt*((a2*W2_new(i,1)^alpha - F1*W2_new(i,1))*W2_new(i,1)+b2*(M-W2_new(i,1))); 
      W3_new1 = W3_new(i,1) + dt*((a3*W3_new(i,1)^alpha - F1*W3_new(i,1))*W3_new(i,1)+b3*(M-W3_new(i,1))); 
      E_F1 = W1_new1 + W2_new1 +W3_new1 - 6; 

      W1_new2 = W1_new(i,1) + dt*((a1*W1_new(i,1)^alpha - F2*W1_new(i,1))*W1_new(i,1)+b1*(M-W1_new(i,1))); 
      W2_new2 = W2_new(i,1) + dt*((a2*W2_new(i,1)^alpha - F2*W2_new(i,1))*W2_new(i,1)+b2*(M-W2_new(i,1)));
      W3_new2 = W3_new(i,1) + dt*((a3*W3_new(i,1)^alpha - F2*W3_new(i,1))*W3_new(i,1)+b3*(M-W3_new(i,1)));
      E_F2 = W1_new2 + W2_new2 + W3_new2- 6; 

      f (i,1) = (F1*E_F2-F2*E_F1)/(E_F2-E_F1);  % the value of f we keep 

      W1_new(i+1,1) = W1_new(i,1) + dt*((a1*W1_new(i,1)^alpha - f(i,1)*W1_new(i,1))*W1_new(i,1)+b1*(M-W1_new(i,1)));
      W2_new(i+1,1) = W2_new(i,1) + dt*((a2*W2_new(i,1)^alpha - f(i,1)*W2_new(i,1))*W2_new(i,1)+b2*(M-W2_new(i,1))); 
      W3_new(i+1,1) = W3_new(i,1) + dt*((a3*W3_new(i,1)^alpha - f(i,1)*W3_new(i,1))*W3_new(i,1)+b3*(M-W3_new(i,1))); 
      E_f = W1_new(i+1,1) + W2_new(i+1,1) + W3_new(i+1,1) - 6;  % this quantity has to be equal to zero

end
end

plot(t, W1_new,'r')

hold on

plot(t,W2_new,'r') 

hold on

plot(t, W3_new,'r')

I WOULD LIKE TO CHANGE THE VALUE OF THE PARAMETER M INSIDE THE FOR LOOP. WHEN T>1.5 THEN M=0.5 RATHER THAN THE SET VALUE OF M=0.8 AND PLOT THIS

THANKS!

Answer 1

[Star Strider]

Just after your for statement, add the two following lines:

for i=1:length(t)-1 

        ti = t(i);
        M = [0.8*(ti <= 1.5) + 0.5*(ti > 1.5)];

        ... CODE ...

That works.