I'm new to solving ode's in Matlab, i followed tutorial, and i do not understand the error

%this is my fxn file

function [Ddv_Div] = ASFxn(Ind,D)

%IV, Ind, IVsol - independent variables
% DV, D, DVsol - Dependent variables 
%S - uninfected and susceptible to infection
%I - infected and able to transmit the virus
%C - survivor individuals which do not transmit the virus but can revert to
     %the infected (I) class
%D - infected carcasses which can transmit the virus
%a(t) -seasonal birth rate
% bp, ba, bh, mortality rate in the absence of the disease (natural death
     % of piglets and adults and death by hunting)
% k is the carrying capacity
%Bf frequenct dependent transmission, though contact with infected
%individual.
%Be environmental transmission through contact with an infected carcass.

Sp = D(1);
Sa = D(2);
Ip = D(3);
Ia = D(4);
Cp = D(5);
Ca = D(6);
D = D(7);
Bf = 63;
Be = 2;
rho = 0.85;
bc = 0;
r = 0;

I = Ip + Ia; %the total infected population
A = Sp + Ia +Ca; % the total adult population
N = Sp + Sa + Ip + Cp + Ca; %the total population of living wild boar
Alpha = 12/10; %average maturation of piglets to adults within 10 months
a_t = (3/2)*A;
bh = 0.69;
ba = 0.05;
    b0 = log(2);
    k = 2; %2Km^-2 in natural populations and 4 Km^-2 under supplementary feeding
    Sig = k/(Sp+Sa+Cp+Ca+Ia+Ip);%the scaling term use to ensure that average population density equals the carrying capcity
    b1 = Sig*((a_t*Alpha-b0*(ba+bh))/(ba+ba)*k);
bp = (b0+b1*N);
y = 365/5; % a portion, rho, of individuals suffer disease induced mortality at rate y =365/5. 
          % a portion of 1 - rho of infected can enter the survivor class,
          % which does not incur disease induced mortality. 
kk = 16/6; % rate at whick survivors can revert back to the infeted class (where they incure disease induced mortality. The value implies that the average time spent in the survivor class is 6 months.
d = 52/8; % decay rate for carcasses. Individuals that dies whilst infected are classed as infected carcasses can transmit infection for on average 8 weeks.
                  % to initiate the model 
I = k * (0.2/100); % a low level of infection. 
Ddv_Div  =[ a_t*A - Bf*(Sp/N)*I - Be*Sp*D - Alpha*Sp - bp*Sp - bc*Sp;
     -Bf*(Sa/N)*I - Be*Sp*D - Alpha*Ip - y*Ip + kk*Cp - bp*Ip - bc*Ip;
     Bf*(Sa/N)*I - Be*Sa*D - Alpha*Ip -y*Ip + kk*Cp - bp*Ip - bc*Ip;
     Bf (Sa/N)*I - Be*Sa*D - Alpha*Ip - y*Ia + kk*Ca - ba*Ia - bh*Ia - bc*Ia;
     y*(1-rho)*Ip - kk*Cp - Alpha*Cp - bp*Cp - bc*Cp;
     y*(1-rho)*Ia - kk*Ca + Alpha*Cp - ba*Ca - bh*Ca - bc*Ca;
     y*rho + bp*Ip - ba*Ia - d*D - r*D; ];
    
end

%this is my script

domain = [0 12];
IC1 = 100; %initial number of piglets susceptible to the virus
IC2 = 90; %initial number of Adult pigs susceptible to the virus
IC3 = 12; %initial number of piglets infected with the virus
IC4 = 8; %initial number of Adult pig infected with the virus
IC5 = 1; %initial number of survivor piglets which do not transmit the virus but can contract again
IC6 = 1; %initial number of survivor adults which do not transmit the virus but can contract again 
IC7 = 3;  %initial number of infected carcasses which can transmit the virus
IC = [IC1 IC2 IC3 IC4 IC5 IC6 IC7];


[IVsol, DVsol] = ode45('ASFxn',domain,IC);

%-------this is the error i get when i run the script-----%

Error using vertcat

Dimensions of arrays being concatenated are not consistent.

Error in odearguments (line 90)

f0 = feval(ode,t0,y0,args{:}); % ODE15I sets args{1} to yp0.

Error in ode45 (line 115)

odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options, varargin);

[Atsushi Ueno]

At first I thought your long statements is written over multiple lines.

Continue Long Statements on Multiple Lines - MATLAB & Simulink - MathWorks

But still error has occured even after my correction.

Ddv_Div = [ ...
    a_t*A - Bf*(Sp/N)*I - Be*Sp*D - Alpha*Sp - bp*Sp - bc*Sp; ...
    -Bf*(Sa/N)*I - Be*Sp*D - Alpha*Ip - y*Ip + kk*Cp - bp*Ip - bc*Ip; ...
    Bf*(Sa/N)*I - Be*Sa*D - Alpha*Ip -y*Ip + kk*Cp - bp*Ip - bc*Ip; ...
    Bf*(Sa/N)*I - Be*Sa*D - Alpha*Ip - y*Ia + kk*Ca - ba*Ia - bh*Ia - bc*Ia; ...
    y*(1-rho)*Ip - kk*Cp - Alpha*Cp - bp*Cp - bc*Cp; ...
    y*(1-rho)*Ia - kk*Ca + Alpha*Cp - ba*Ca - bh*Ca - bc*Ca; ...
    y*rho + bp*Ip - ba*Ia - d*D - r*D ];

This style below does work. I don't know why your style above does not work.

ty1 = a_t*A - Bf*(Sp/N)*I - Be*Sp*D - Alpha*Sp - bp*Sp - bc*Sp;
ty2 = -Bf*(Sa/N)*I - Be*Sp*D - Alpha*Ip - y*Ip + kk*Cp - bp*Ip - bc*Ip;
ty3 = Bf*(Sa/N)*I - Be*Sa*D - Alpha*Ip -y*Ip + kk*Cp - bp*Ip - bc*Ip;
ty4 = Bf*(Sa/N)*I - Be*Sa*D - Alpha*Ip - y*Ia + kk*Ca - ba*Ia - bh*Ia - bc*Ia;
ty5 = y*(1-rho)*Ip - kk*Cp - Alpha*Cp - bp*Cp - bc*Cp;
ty6 = y*(1-rho)*Ia - kk*Ca + Alpha*Cp - ba*Ca - bh*Ca - bc*Ca;
ty7 = y*rho + bp*Ip - ba*Ia - d*D - r*D;
Ddv_Div = [ty1; ty2; ty3; ty4; ty5; ty6; ty7;]; 

[Atsushi Ueno]

Also, your code has lack of "*" (asterisk for multiplication).

 Bf (Sa/N)*I - Be*Sa*D - Alpha*Ip - y*Ia + kk*Ca - ba*Ia - bh*Ia - bc*Ia;

[DKO]

@Atsushi Ueno Thank you so much

Answer 1

[Cris LaPierre]

The dimension error is due to this line, with the problematic part indicated:

[...
Bf*(Sa/N)*I - Be*Sa*D - Alpha*Ip -y*Ip + kk*Cp - bp*Ip - bc*Ip;
%                                ^^
];

When building an array using square brackets, you either need to have a space between your minus sign and the following expression, or no spaces on either side. When inside square brackets, the "-y*Ip" is saying 'negative y times Ip' and not 'minus', resulting in two separate numbers.

As a simplified example, consider the following

% With square brackets
[5 - 3]

ans = 2

[5 -3]

ans = 1×2

5 -3

[5-3]

ans = 2

% Without square brackets
5 - 3

ans = 2

5 -3

ans = 2

5-3

ans = 2

With this fixed and the missing * added in the 4th line (after Bf), the code runs without error, though it does not arrive at a solution.

[DKO]

@Cris LaPierre Thank you so much.