Why do I get the error “Index exceeds matrix dimensions.”?

I keep getting this error:

??? Index exceeds matrix dimensions.

Error in ==> example3_6 at 48 results=regress(cl1(trainset), cl2(trainset)); % use regression function

GDX file contains 7 columns and 386 rows, GLD file contains 7 columns and 765 rows, but if i'm taking a sample of 250 out of both this should not be a problem.

Can somebody advise what is the problem here?

Thank you

 clear; % make sure previously defined variables are erased.

 [num, txt]=xlsread('GLD'); % read a spreadsheet named "GLD.xls" into MATLAB. 

 tday1=txt(2:end, 1); % the first column (starting from the second row) is the  trading days in format mm/dd/yyyy.

 tday1=datestr(datenum(tday1,'mm/dd/yyyy'), 'yyyymmdd');

 tday1=str2double(cellstr(tday1)); % convert the date strings first into cell arrays and then into numeric format.

 adjcls1=num(:, end); % the last column contains the adjusted close prices.

 [num, txt]=xlsread('GDX'); % read a spreadsheet named "GDX.xls" into MATLAB. 

 tday2=txt(2:end, 1); % the first column (starting from the second row) is the trading days in format mm/dd/yyyy.

 tday2=datestr(datenum(tday2,'mm/dd/yyyy'), 'yyyymmdd');

 tday2=str2double(cellstr(tday2)); % convert the date strings first into cell arrays and then into numeric format.

 adjcls2=num(:, end); % the last column contains the adjusted close prices.

 [tday, idx1, idx2]=intersect(tday1, tday2); % find the intersection of the two data sets, and sort them in ascending order

 cl1=adjcls1(idx1); 

 cl2=adjcls2(idx2);  

 trainset=1:252; % define indices for training set

 testset=trainset(end)+1:length(tday); % define indices for test set

 % determines the hedge ratio on the trainset
 results=ols(cl1(trainset), cl2(trainset)); % use regression function 
 hedgeRatio=results.beta;

[Azzi Abdelmalek]

the line where you get an error message is'nt posted!

Answer 1

[Matt J]

Some indices contained in "trainset" are outside the bounds of legitimate indices for cl1 or cl. I.e., you've done something like this:

>> x=1:5; x(6)
Index exceeds matrix dimensions.

Answer 2

[Nagham Kabbara]

i know this is an old post, but i am having the same problem but the difference is that i know the size of the matrix and i'm setting a loop for i=1:nbrows and still i am getting this message!!!

this is so illogical!!!!!

Answer 3

[John]

I ran the size() function and this is what i get

size(cl1) ans = 2 1 
size(trainset) ans = 1 252

I'm sure the error is because i'm plugging a 1:252 vector into a 2:1 matrix, but how do i change the 2:1 matrix size to fit the vector in? This is the first time i'm using matlab, so i'm not really familiar with it.

[Matt J]

No, that's not the reason. As you can see from the following example, there is no reason trainset can't be longer than cl.

    >> cl=[ 5; 6]; trainset=ones(1,252); z=cl(trainset);

    >> whos cl trainset z

      Name            Size             Bytes  Class     Attributes

      cl              2x1                 16  double              
      trainset        1x252             2016  double              
      z             252x1               2016  double

You need to look at max(trainset) and see if it's greater than length(cl). Or, if you know that cl is too short in length, then review how cl1 is generated. Only you can possibly know the purpose cl1 is supposed to serve here and how long it should be if it is doing the correct thing.

Answer 4

[John]

ok i figured it out, there was a problem in date format

[Tim]

I am getting the same error, any chance you could share the date formatting problem and solution?

[Tim]

Nevermind, my problem was using the MATLAB function names, "year" and "month", as my looping variables. Just changed them to 'yr' and 'mo' and my code ran fine. Thanks anyway.

Answer 5

[MathWorks Support Team]

Typically you encounter this error when you try to access an element of an array that does not exist. For example, in R2017b and earlier releases:

A = [1 7 9 3];
A(5)

, results in this error because you are trying to access the fifth element of A, which does not exist.

In R2018a and later, this error is replaced by the following error:

"Index exceeds the number of array elements (4)."

For additional information on indexing, see:

https://www.mathworks.com/help/matlab/math/matrix-indexing.html.

Answer 6

[veerendra babu arigela]

Warning: Could not evaluate MaskDisplay commands of block 'veeru/Diode':

Undefined variable "X" or class "X.p1".

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pls help me it is showing "index exceeds matrix dimension"