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Error using Odearguments - vector must return a column

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I kept on trying to reword and rearrange my code however it asked me to do it so that the line return a column vector. I tried reshape(), [],1, (does not work). Also tried .' at the end which also doesnt work. I'm not sure where I can continue with this?
%r_H2= -(-Rds - Rwf - Rh);
%Rd = kds*(CH20*((theta_O2-X)/(1+eps*X)))*(CH20*((1-X)/(1+eps*X)))^2
%Rwf = kwf* (CH20*((theta_O2-(b/a)*X)/(1+wf_eps*X)))^.5*CH20.*((1-X)./(1+wf_eps*X))
%Rh = kh* (CH2O2*(theta_H2-(d_b/d_a)*X)) *CH2O2*(1-X)
wspan = [0 1000];
dxdw = @(W,X)(kds.*(CH20.*((theta_O2-X)./(1+eps.*X))).*(CH20.*((1-X)./(1+eps.*X))).^2 + ...
kwf.* (CH20.*((theta_O2-(b/a).*X)./(1+wf_eps.*X))).^.5*CH20.*((1-X)./(1+wf_eps.*X))+ kh.* (CH2O2.*(theta_H2-(d_b/d_a).*X)) .*CH2O2.*(1-X));
IC = [0 0 0 0 0 0 0 0 0 0 0];
[W,X] = ode45(dxdw,wspan,IC);
plot(W,X)
title ('Catalyst v.s Conversion')
xlabel('Weight of Catalyst (kg)')
ylabel('Conversion of H2')

Accepted Answer

Star Strider
Star Strider on 17 Apr 2024
You only have one differential equation, so only one initial condition is necessary.
%r_H2= -(-Rds - Rwf - Rh);
%Rd = kds*(CH20*((theta_O2-X)/(1+eps*X)))*(CH20*((1-X)/(1+eps*X)))^2
%Rwf = kwf* (CH20*((theta_O2-(b/a)*X)/(1+wf_eps*X)))^.5*CH20.*((1-X)./(1+wf_eps*X))
%Rh = kh* (CH2O2*(theta_H2-(d_b/d_a)*X)) *CH2O2*(1-X)
wspan = [0 1000];
dxdw = @(W,X)(kds.*(CH20.*((theta_O2-X)./(1+eps.*X))).*(CH20.*((1-X)./(1+eps.*X))).^2 + ...
kwf.* (CH20.*((theta_O2-(b/a).*X)./(1+wf_eps.*X))).^.5*CH20.*((1-X)./(1+wf_eps.*X))+ kh.* (CH2O2.*(theta_H2-(d_b/d_a).*X)) .*CH2O2.*(1-X));
% IC = [0 0 0 0 0 0 0 0 0 0 0];
IC = eps;
[W,X] = ode45(dxdw,wspan,IC);
Unrecognized function or variable 'kds'.

Error in solution>@(W,X)(kds.*(CH20.*((theta_O2-X)./(1+eps.*X))).*(CH20.*((1-X)./(1+eps.*X))).^2+kwf.*(CH20.*((theta_O2-(b/a).*X)./(1+wf_eps.*X))).^.5*CH20.*((1-X)./(1+wf_eps.*X))+kh.*(CH2O2.*(theta_H2-(d_b/d_a).*X)).*CH2O2.*(1-X)) (line 6)
dxdw = @(W,X)(kds.*(CH20.*((theta_O2-X)./(1+eps.*X))).*(CH20.*((1-X)./(1+eps.*X))).^2 + ...

Error in odearguments (line 92)
f0 = ode(t0,y0,args{:}); % ODE15I sets args{1} to yp0.

Error in ode45 (line 104)
odearguments(odeIsFuncHandle,odeTreatAsMFile, solver_name, ode, tspan, y0, options, varargin);
plot(W,X)
title ('Catalyst v.s Conversion')
xlabel('Weight of Catalyst (kg)')
ylabel('Conversion of H2')
All the missing constants prevent me from running this.
.
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More Answers (1)

Torsten
Torsten on 17 Apr 2024
Moved: Torsten on 17 Apr 2024
This works - although I'm not sure if it is what you want:
wspan = [0 1000];
CH2O2 = @(X)CH20.*((theta_H2O2+X)./(1+eps*X))*T0T*PP0;
dxdw = @(W,X)(kds.*(CH20.*((theta_O2-X)./(1+eps.*X))).*(CH20.*((1-X)./(1+eps.*X))).^2 + kwf.* (CH20.*((theta_O2-(b/a).*X)./(1+wf_eps.*X))).^.5*CH20.*((1-X)./(1+wf_eps.*X))+ kh.* (CH2O2(X).*(theta_H2-(d_b/d_a).*X)) .*CH2O2(X).*(1-X));
IC = eps*ones(11,1);
[W,X] = ode15s(dxdw,wspan,IC);
And better use a variable name different from eps. It usually is a predefined constant is MATLAB:
eps
ans = 2.2204e-16

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