MATLAB: How to iterate and plot in matlab

derivativeiterationploturgent

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.

Best Answer

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);

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MATLAB: How to plot an integral

‘But nothing comes out on the graph.’

The result of the int function is a constant. At best, you will get a straight line.

I am not certain what you want. You can get it to plot as a function of the upper limit of integration by creating a function from it:

syms x a 
kw = 91371;
CaO= 1.81*10^(-4);
FaO= 0.1233;
K = 1.29;
fun = FaO*((1+K*CaO*(1-x))/(kw*CaO*(1-x)));
W(a) = int(fun, x, 0, a);
fplot(W,[0 1])

MATLAB: Plot two lines on different graphs from integral

I guess you are trying to do something like this. Note that I have varied x from 0 to 0.9, because at x=1, the integral diverges.

To=27+273.15;  %%k
cao=0.1;    %%mol/dm^3
k1=.01;  %%dm^3/mol*s
tha=1;thb=1;
ha=-20000; hb=-15000; hc=-41000; %%cal/mol

cpc=30;cpa=15;cpb=15; %%cal/mol*k

sumtcp=tha*cpa+thb*cpb;
delcp=cpc-cpb-cpa;
dhrx=hc-hb-ha;
E=10000;                       %%cal/mol
R=1.987;        %%cal/mol*k
vo=2;
fao=cao*vo;
cbo=cao;
ca=@(x) cao*(1-x);
cb=@(x) cbo*(1-x);
T=@(x) To+(-dhrx)*x./(sumtcp+delcp.*x); % <----- element-wise division should be used
k=@(x) k1*exp(E/R.*(1/To-1./T(x))); % <----- element-wise operators should be used
ra=@(x) -(k(x).*ca(x).*cb(x));
vpfr1=@(x) fao./(-ra(x));
x = 0:0.1:0.9;
vpfr = zeros(size(x));
for i=1:numel(x)
    vpfr(i) = integral(vpfr1,0,x(i));
end
plot(x, vpfr);
figure;
plot(T(x), vpfr);

Best Answer

Related Solutions

MATLAB: How to plot an integral

MATLAB: Plot two lines on different graphs from integral

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