MATLAB: Help with ‘Index out of bounds error’

boundsindexMATLABout of

Here is my code so far
% Chris Corbett;
% Set 16;
% User input for the galaxy number, with result treated as string;
x = input('Please choose a number from 1 to 5 for the galaxy number: ','s');
% Reading in the galaxy data;
g = ['galaxy',x,'.txt'];
a = dlmread(g);
% Taking the wavelength from the data;
w = a(:,1);
% Taking the flux from the data;
f = a(:,2);
% Plotting the flux against the frequency;
plot (w,f);
xlabel ('Wavelength (nm)');
ylabel ('Spectral Flux (Arbitrary Units)');
title (['Graph for Galaxy ',x]);
% Importing the red shift data;
r = dlmread('redshifts.txt');
% Picking out associated red shift;
s = r(x,2);
% Importing the wavelength data;
y = dlmread('wavelengths.txt');
% Calculating the observed wavelength;
obsw = y.*(1+s);
plot(obsw,0.5,'kd')
It involves taking data from various files and then plotting various graphs with it. If more explanation is needed on this I can explain it. But basically
Galaxy# has 2 columns and a lot of rows (too many too count) Redshifts has 2 columns and 5 rows Wavelengths has 1 column and 8 rows
When I run the code I get the error
??? Attempted to access r(49,2); index out of bounds
because size(r)=[5,2].
I'm guessing this is perhaps something to do with the program thinking r is bigger than it is.
If I add a line just before the red shift data is imported that sets x to a value, such as x = 1; There is no problem.
I'm really not sure how to fix this, does anybody have any suggestions?
Thank you. Chris

Best Answer

You input x as a string (character), but then you try to use that character as the array index.
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