Error in ode45 (line 115) odeargumen​ts(FcnHand​lesUsed, solver_name, ode, tspan, y0, options, varargin);

%%parameters

C = 1; %concentration of contaminant

O = 1; %concentration of oxygen

B = 1; %concentration of microorganism

Do = 0.2; %diffusivity constant

Dc = 0.2; %diffusivity constant

v = 1; %velocity

Ko = 0.1; %half-saturation constant of oxygen

Kc = 0.1; %half-saturation constant of the substrate

Kd = 0.125; %degradation constant

Yc = 0.125; %mass of bacteria

dx = 0.2; %spatial space

dt = 0.002; %time interval

mu = 0.1; %viscosity

delta = 1;

%%equation used

%%d(C)/d(t) = delta(Dc*delta*C-vC)- mu*B/Yc*(C/C+Kc)*(O/O+Ko)

%%d(O)/d(t) = delta(Do*delta*C-vC)- mu*B/Yc*(C/C+Kc)*(O/O+Ko)

%%d(B)/d(t) = mu*B*(C/C+Kc)*(c/c+Kc)-Kd*B

f = @(t,a) [delta(Dc*delta*C-vC)- mu*B/Yc*(C/C+Kc)*(O/O+Ko); -delta(Do*delta*C-vC)- mu*B/Yc*(C/C+Kc)*(O/O+Ko); mu*B*(C/C+Kc)*(c/c+Kc)-Kd*B; ];

xt0 = [0.323,10,9];

[tspan,a] = ode45(f,[0 50],xt0);

figure

plot(tspan,a(:,1),tspan,a(:,2),tspan,a(:,3))

xlabel('time')

ylabel('Concentration(mg/l)')

[JANMAY JAY GAUTAM]

i am new to matlab please help

Answer 1

[Walter Roberson]

delta = 1;

That is a numeric scalar. Valid indices for it are numeric 1, logical true, logical false, and the empty vector. Any index for delta that does not evaluate to one of those will be out of range.

f = @(t,a) [delta(Dc*delta*C-vC)- mu*B/Yc*(C/C+Kc)*(O/O+Ko); -delta(Do*delta*C-vC)- mu*B/Yc*(C/C+Kc)*(O/O+Ko); mu*B*(C/C+Kc)*(c/c+Kc)-Kd*B; ];

Dc*delta*C-vC is not evaluating to 1 or the empty array, and so you have index out of range.

Reminder: there are very few programming languages that support implied multiplication, as it introduces too many ambiguities. For example is x(3) intended to indicate x being indexed at 3, or is it intended to indicate that x is being multiplied by an expression that happens to have been stated in parentheses? If 3x is considered to mean that x is to be multiplied by 3 then is x3 intended to indicate a different variable name or to indicate that x is being multiplied by 3?