How to plot a isovolumetric pressure loop for a left venticle model?

Hi, I need some major help, Im tasked with using matlab to build a preesure- volume loop to model the left ventricle but have absolutely no idea how to put the equations into matlab properly.

Here is my code:

    % solves the steady state pressure-volume model for the left venticle
    global R0 Rs Cs Rin Pr a b c d Tp Ts T Vv;
    R0 = 0.06; % mmHg.s/cm^3
    Rs = 1.0; % mmHg.s/cm^3
    Cs = 2.75; % cm^3/mmHg
    Rin = 0.001; % mmHg.s/cm^3
    Pr = 10; % mmHg
    a= 0.0005;% mmHg/cm^3
    b = 6.0;% cm^3
    c = 1.5;% mmHg/cm^3
    d = 1.0; % mmHg
    Tp = 0.35; % s
    Ts = 0.8; % s
    T = 1.0; %  s
    Vv = 250; % ml

    % solve model

        if true
          % code
        end
    [time, Yout] = ode15s('IPM', [0 20], [0 100]);

    % plot model

    plot(time, Yout(:,2)),xlabel('Volume'), ylabel('Pressure (mmHg)'), ...
    title('Steady State Pressure Volume loop of the Left Ventricle');

And my function:

function Yprime = IPM(t,Y)
  Yprime = zeros(2,1);
  global R0 Rs Cs Rin Pr a b c d Tp Ts T;
  % first, determine phase time within each beat
  tt = mod(t,T);
  % next, calculate ventricular pressure
   if (tt < Tp)
        f = (sin((pi*tt)/(2*Tp)))^2;
   elseif (tt < Ts)
           f=(cos((pi*(T-Tp))/(2*(Ts-Tp))))^2;
      else 
          f = 0;
   end;
  Ps = Y(1);
  Vv = Y(2);
  Pv = a*(Vv-b)^2 +(c*Vv-d)*f;

    if (Pr > Pv)
        Qin = (Pr-Pv)/Rin;
    else 
        Qin = 0;
    end
    if (Pv>Ps)
        Qout= (Pv-Ps)/R0;
    else
        Qout = 0;
    end

    Yprime (1) = Qout/Cs -Ps/(Rs*Cs);
    Yprime (2) = Qin - Qout;

it should be a loop but currently is more like a square wave plot

[Ananthi P]

Hi, did you get answer to the above question? If yes, please let me know, that will be very helpful. I have a similar problem to solve.

[ola ahmed]

can you please help me with the main equations?

I'm tring to make the same program but i think iam missing an eqution so I am stuck in a loop

[Sulaymon Eshkabilov]

What is your equation that you are trying to simulate?