How do I rectify the problem of [subscripted assignment dimension mismatch; at Line: dmdt(1) = N]? Much Thanks!

function dmdt = fyp(t,m)

tspan = [0:33];
%Time intervals (Mins?)

dmdt = zeros (4,1); 

% this creates an empty column vector that i can fill with my 4

% derivatives

%SuperSaturation of fluid 

%Ci read from graph 

%C f(MT)

C = 80.2;

%Ct = C - Mt

% Temperature of Solution (Celcius)

T = [90:-2:24]'; 

% Brix 

Brix = (64.47+0.10336*T+14.20*10.^-4*T.^2-70.2*10.^-7*T.^3);

%Satuation Concentration 

CS = (Brix/(100-Brix));

%Supersaturation
%CC = C - CS(sat)

CC = C - CS;

% Nucleation order,b = 1.5

b = 1.5;

%Exponential of Mass of Crystal 

Z = 0.4136;

%Density of Crystal

Density = 1588.4/(1+1.116*10.^4*(T-20));

%Shape Factor (Cube Shape, 1)

Kv = 1; 

%Mass of Crystal 
%m(4) is moment 3
%MT = Density*Kv*m(4); 

global MT

%Rate of Nucleation

%Kb.C(Sat)^B.MT^J

Kb = 3.1512*10.^13*exp(-(78.752)/(0.008314*T));

N = Kb*CC.^b*MT.^Z;

%Growth Order 

g = 1 ;

%Rate of Growth 

Kg = 2.2439*10^6*exp(-(46.550)/(0.008314*T));

G = Kg*CC.^g;

dmdt (1,1) = N;

% in this case m(1) is moment 0 

dmdt(1,2) = m(1)*G;

% m(2) is moment 1

dmdt(1,3) = 2*m(2)*G;

% m(3) is moment 2

dmdt(1,4) = 3*m(3)*G;

% m(4) is moment 3

%Initial Value 
%y0 [0 0 0 0]de

%solve ode 45 
end

Answer 1

[Adam]

It depends what you intended as to how to fix it. Use a cell array if you really want to store everything that is returned. Your predeclaration suggests you expect 4 numeric results in your dmdt array though.

Basically T is a vector, Brix is a function of t, CS is a function of Brix, CC is a function of CS and N is a function of CC.

Without running your code I can't easily tell if there are matrix multiplications there which you would expect to reduce the dimensionality back down to being a scalar, but assuming not then N will be a vector of the same size T was so you cannot assign it to dmdt(1,1) which is, of course a single scalar element of a matrix.

[Joshua Ong]

Thanks Adam!!! Appreciate it!