How to iterate and plot in matlab

Hello! I need some help with Matlab.

I would like to solve and plot the following function:

I've called dxa/dW 'y', and I know everything except for xa, which I'd like to iterate from 0 to 1 in steps of 0.05. This is what I have written, but I am obviously doing something wrong because it gives me an error.

I would really apreciate it if you could help because I need it as soon as possible for my thesis.

Thank you in advance.

Answer 1

[Floris]

Hello,

Maybe I misunderstand what you are attempting to do, so please let me know if you need any additional clarification. I notice you are varying x from 0 to 1, however, you do not seem to have the variable W in the equation where you define y. In order to plot W, you will need to map W using linspace() as well as X. Checkout the link below for help on what I think you are trying to do:

https://www.mathworks.com/videos/plotting-multiple-lines-on-a-figure-in-matlab-97201.html

So I have the following code below:

x = linspace(0,1,200);

kw = 91371;
Ca0 = 1.81 * 10 ^ -4;
Fa0 = 0.1233;
K = 2;


y = (1/Fa0) * ((kw .* Ca0 .* (1 - x)) ./ (1 + K .* Ca0 .* (1 - x)))

plot(x, y);

[darova]

+1

[darova]

You don't have to put "." (point) everywhere. Just when you do some operations between vectors:

y = 1/Fa0*kw*Ca0*(1 - x) ./ (1+K*Ca0*(1 - x));

[Marina Gonzalez]

Thank you all so much. That really helped. I have one last question.

I've separated the variables so now the equation looks like this:

I've plotted it in Excel and the graph it gives me is correct because I know it should have that shape:

But I can't write it properly on Matlab. Now that I know it is correct, I need some help with the Matlab code. This is what I've written:

x = linspace(0,1,200); % conversion
%CONSTANTS
kw = 91371; % [1/(s*g)]
Ca0 = 1.81*10^-4; % [mol/l]
Fa0 = 0.1233; %[kg/s]
K = 1.29; %[l/mol]

%EVOLUTION OF THE CONVERSION 'x' AS A FUNCTION OF THE MASS CATALYST 'W'
W = x.*Fa0.*(1+K.*Ca0.*(1 - x)) ./ kw.*Ca0.*(1 - x);
plot (x,W);

Thank you again.

[darova]

You forgot parentheses at the end:

W = x.*Fa0.*(1+K.*Ca0.*(1 - x)) ./ kw.*Ca0.*(1 - x);

Don't know if your expression for W is correct

[Marina Gonzalez]

How would I write it on Matlab to solve the expression you wrote and plot x vs W? Take into account that x should be values between 0 and 1.

[darova]

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