When I print the value of the boolean inside of my if statement inside of my ode function, it reports back values of 0, yet it continues to run inside of the if statement. Because the boolean is not true, the if statement is false and therefore should proceed to the else statement, but it is not the case here. Specifically, the if statement is running when x(4) deltaXleft or x(4) deltaXright. I don't know what to make of this. function xdot = memsODE(t,x,K) m = [4.97e-07 5.1289e-06]; b = [1e-6 1e-6]; %N*s/m P = 5.9295e6; %Pa -> N/m^2 = 860 psi A = 2.2e-7*10; %m^2 x1closed = 50e-6; deltaXleft = 950e-6; deltaXright = -50e-6; %Find f1 X0 = 49e-6; A1 = 0; A2 = 1; dx = 1e-6; f1 = (A1 - A2) ./ (1 + exp((X0 - x(1))/dx)) + A2; %Find f2 if x(1) 0) && ((x(3) - x(1)) >= deltaXleft)) || (((x(3) - x(1)) 0) && ((x(3) - x(1)) >= deltaXleft)) || (((x(3) - x(1)) <= deltaXright) && (x(4) < 0))) else xdot(1) = x(2); xdot(2) = -1*(b(1)*x(2) + K(1)*x(1) + f2*K(3)*(x(1) - x1closed))/m(1); xdot(3) = x(4); xdot(4) = -1*(b(2)*x(4) + K(2)*x(3) - f1*P*A)/m(2); end

If logic issues inside ode45

AndrewC

2018 10 18

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When I print the value of the boolean inside of my if statement inside of my ode function, it reports back values of 0, yet it continues to run inside of the if statement. Because the boolean is not true, the if statement is false and therefore should proceed to the else statement, but it is not the case here. Specifically, the if statement is running when x(4) < 0 but (x(3) - x(1)) > deltaXleft or x(4) < 0 but (x(3) - X(1)) > deltaXright. I don't know what to make of this.

function xdot = memsODE(t,x,K)
    m = [4.97e-07 5.1289e-06];
    b = [1e-6 1e-6]; %N*s/m 
    P = 5.9295e6; %Pa -> N/m^2 = 860 psi 
    A = 2.2e-7*10; %m^2 
    x1closed = 50e-6;
    deltaXleft = 950e-6;
    deltaXright = -50e-6;
    %Find f1
    X0 = 49e-6;
    A1 = 0;
    A2 = 1;
    dx = 1e-6;
    f1 = (A1 - A2) ./ (1 + exp((X0 - x(1))/dx)) + A2;
    %Find f2
    if x(1) < x1closed
        f2 = 0;
    else 
        f2 = 1;
    end
    %Equations of Motion
    if ((x(4) > 0) && ((x(3) - x(1)) >= deltaXleft)) || (((x(3) - x(1)) <= deltaXright) && (x(4) < 0)))
            xdot(1) = x(2);
            xdot(2) = -1*((b(1) + b(2))*x(3) + (K(2)*x(3) + K(1)*x(1)) + f2*K(3)*(x(1) - x1closed) - P*A*f1)/(m(1) + m(2)); 
            x(4) = x(2);
            xdot(3) = x(4);
            xdot(4) = xdot(2);
            % print boolean value
            ((x(4) > 0) && ((x(3) - x(1)) >= deltaXleft)) || (((x(3) - x(1)) <= deltaXright) && (x(4) < 0)))
    else 
            xdot(1) = x(2);
            xdot(2) = -1*(b(1)*x(2) + K(1)*x(1) + f2*K(3)*(x(1) - x1closed))/m(1);
            xdot(3) = x(4);
            xdot(4) = -1*(b(2)*x(4) + K(2)*x(3) - f1*P*A)/m(2);
    end