Error using "superiorfloat" with ODE23

Hello,

I've been getting the following error when I try to use ODE23 solver:

• Error using superiorfloat: Inputs must be floats, namely single or double.
• Error in HW2_3MWK (line 52): [t_m3,P_m3] =ode23(Y3, [(n-1)*Tc; n*Tc] , P0_WK3);

The code in question is the following:

Y3= @(t,y3) (-y3/(R2*C)+I(t)*(R2+R1)/(R2*C)+R1); 
[t_m3,P_m3] = ode23(Y3, [(n-1)*Tc; n*Tc] , P0_WK3);
P0_WK3=P_m3(end); 

Where R1, R2, C, Tc, and P0_WK3 are pre-stablished constants. (Full code attached)

This code has worked in the past, which is almost 12 years ago (it is not mine), and wanted to re-purpose it for a project. Any ideas?

Thanks in advance!!!

-JD

%%Catanho et al, 2012. Use of numerical solution and MATLAB ODE solver to
%%present the 3-Module model.
close all;
clear ;
colour = hsv;

%Initial parameters 
R1 = 0.05; %Systemic resistance from the aorta (mmHg/cm^3/sec)
R2 = 0.9;  %Systemoc resistance from the peripheral vessels (mmHg/cm^3/sec)
C = 1.067; %Compliance of the aorta (cm^3/mmHg)

%Assumptions
Tc = 0.8333; %Duration of the cardiac cycle
Ts = (2/5)*Tc; %Duration of systole
cycle = 5; %Amount of cycles considered by the model

%Modelling of the Blood flow in the aorta
%Numerical solution of the integral below will give the estimated flow into
%the aorta per cardiac cycle.
syms Ti q
I0 = solve(90-int(q*(sin(pi*Ti/Ts)),Ti,0,Ts),q);
I0 = subs(I0, '3.14', pi);
sine = @(t) sin(pi*t/Ts); 
I = @(t) I0*sine(t).*(t <= Ts); 

%Now that the blood flow in a single cycle has been determined, now we will
%see effect of the 3-Module WM over the specified number of cycles

figure(1)
for n =1 : cycle
    
    t = (n-1)*Tc:0.01:n*Tc;

    %Blood flow over n cardiac cycle(s)
    I=@(t) I0*sine(t-(n-1)*Tc).*(t <= ((n-1)*Tc+Ts)) ; 

    subplot(2,1,1) 
    plot (t, I(t), 'LineWidth' , 2) 
    hold on 
    xlim([0 n*Tc]) 
    ylim([ 0 600]) 
    title('Aortic Blood Flow') 
    ylabel('Blood Flow (mL/s)') 
    xlabel('time(s)') 

    P0_WK3 = 80; %Initial pressure for the 3-MWK model

    %%Numerical Solution for 3 ElementWM 
    
    Y3=@(t,y3) (-y3/(R2*C)+I(t)*(R2+R1)/(R2*C)+R1); 
    [t_m3,P_m3] =ode23(Y3, [(n-1)*Tc; n*Tc] , P0_WK3);
    P0_WK3=P_m3(end); 

    subplot(2,1,2) 
    plot(t_m3,P_m3, 'LineWidth' , 2) 
    hold on 
    ylim([ 0 150]) 
    xlim([0 n*Tc]) 
    title('Aortic Blood Pressure (Numerical 3 ElementWM)') 
    ylabel('Pressure (mmHg)') 
    xlabel('time(s)') 

    
end

Error using superiorfloat
Inputs must be floats, namely single or double.

Error in odearguments (line 114)
dataType = superiorfloat(t0,y0,f0);

Error in ode23 (line 102)
odearguments(odeIsFuncHandle, odeTreatAsMFile, solver_name, ode, tspan, y0, options, varargin);

Answer 1

[Torsten]

Replace the line

I0 = subs(I0, '3.14', pi)

by

I0 = double(I0)