Why is my plot function does show any graph?
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Mohamad Khairul Ikhwan Zulkarnain
on 13 Aug 2018
Commented: dpb
on 13 Aug 2018
I have the following code which is shown below:
% creating a multidimensional array
files = dir('*txt') ; % you are in the folder with text files
N = length(files) ;
names = {files(:).name}' ;
iwant = cell(N,1) ;
for i = 1:N
iwant{i} = importdata(files(i).name) ;
end
% type iwant{i} where i refered to 1,2,3,....,n which refered to the number
% that has been assigned to each chemical element
A = input('Please enter an element in form of iwant{i}:');
% find the number of samples
n = length (A(:,1));
% step change for the wavelength
step = 0.02;
% wavelength which is at the centre
p = A(:,1);
% to make new wavelength for each of wavelength in the samples
for j=1:n
new_wavelength(j,:) = p(j)-step*10:step:p(j)+step*10;
end
format shortG
j = input('input number of row:')
Delta_lambda = 0.2
for k = 1:21;
numerator = new_wavelength(j,11)-new_wavelength(j,k)
denominator = Delta_lambda/2;
Denom = 1+(numerator/denominator)^2;
Intensity = 1/Denom
end
hold on
plot(new_wavelength(j,:),Intensity)
But i dont know why when i run it, it does not show any plot. Could anyone fix this up? I will include textfile as well
2 Comments
Accepted Answer
dpb
on 13 Aug 2018
Edited: dpb
on 13 Aug 2018
In
for k = 1:21;
numerator = new_wavelength(j,11)-new_wavelength(j,k)
denominator = Delta_lambda/2;
Denom = 1+(numerator/denominator)^2;
Intensity = 1/Denom
end
hold on
plot(new_wavelength(j,:),Intensity)
you overwrite Intensity every pass through the loop so there's only a single point at the end. There is a plot, it's probably just a single pixel so you don't notice there being a point.
The above could be rewritten as
denominator = Delta_lambda/2; % this is a constant
K=21; % the upper limit of the loop magic number
numerator = new_wavelength(j,11)-new_wavelength(j,1:K); % vectorize to have 21 elements
Intensity = 1./(1+(numerator/denominator).^2); % ditto for result
plot(new_wavelength(j,:),Intensity)
8 Comments
dpb
on 13 Aug 2018
Dunno, would have to see the actual code used...
What does
whos new_wavelength Intensity
return to verify what you actually calculated?
You also need to learn to use the debugger to examine your code so you can learn to find and fix logic errors on your own... :)
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