How to plot an integral function(x) with limits as 10 and x.

%% Function that describes the integrand
Ca = 1;  
V = 100; 
v = 10; 
k = 0.23; 
r = -k*Ca;
Fao = v*Ca;

%% Funtion to solve
fp = @(Fa) -1./k.*Fa./v
fh = @(Fa) 100 - integral(fp,Fao,Fa);

%% Plot the function to estimate
c=linspace(0.0,1.0);
plot(c,fh(c));

[Mohammad Kaif]

[Mohammad Kaif]

This is the question.

Answer 1

[Vedant Shah]

Hi @Mohammad Kaif,

Upon reviewing the code, I identified the issue: one of the limits of the “integral” function is being passed as a vector, while the “integral” function only supports scalar limits. To compute the integral for an entire vector, it is necessary to evaluate it element by element. The MATLAB function “arrayfun” can be employed for this purpose. For further details, please refer to the documentation by entering the following commands in the MATLAB command line:

web(fullfile(docroot, "/matlab/ref/arrayfun.html")) 
web(fullfile(docroot, "/matlab/ref/integral.html")) 

To resolve the issue and ensure the code functions correctly, consider the following modification:

% Funtion to solve
fp = @(Fa) 1 ./ (-k * Fa / v); 
fh = @(Fa) V - integral(fp, Fao, Fa);  

% Plot the function to estimate
c = linspace(0, 1, 100); 
fh_values = arrayfun(fh, c); 
plot(c, fh_values); 

This adjustment addresses the problem related to the “integral” function, allowing you to proceed with your task seamlessly.