Error: Index exceeds array bounds.

Hi,

I have read multiple posts related to the subject error but couldn't find the answer related to my query. Any help is much appreciated.

I have an excel file (256x2) and I am reading it in MATLAB with xlsread. The task is to find a number (coming from an input data array) in the first column and locate its neighbouring second column entry. I am doing it by following way.

V = Excel_file(Excel_file(:,1) == Column1(i),:);
        modTemp=V(2);

After locating the respective entry, subtract it from 256 and store the result in mod_cal variable which is also declared as an array.

        mod_cal(i)=256-modTemp;

The code is doing fine uptill here. Problem begins in the next part. I have to find the mod_cal variable's value in the second column now and whatever its respective neighbouring entry would be in the first column, i need to read it in an array named mod_MulInverse and that is going to be my result.

         W = Excel_file(Excel_file(:,2) == mod_cal(i),:);
          mod_MulInverse(i)=W(1);

Complete code is as follows.

mod_cal=zeros(1, 256);
mod_MulInverse=zeros(1,  256);% for storing the values with 256-col2

Excel_file = xlsread('powerValues.xlsx');
for i=1:256 % see excell, we want to go from 0 to 256 (Exclude first 2 entries)
    if(Column1(i)==0 || Column1(i)==1) %OR condition
        mod_cal(i)=Column1(i);
        mod_MulInverse(i)=Column1(i);
    else
        V = Excel_file(Excel_file(:,1) == Column1(i),:);
        modTemp=V(2);
        mod_cal(i)=256-modTemp; %256-alphapower
        
        W = Excel_file(Excel_file(:,2) == mod_cal(i),:);
        mod_MulInverse(i)=W(1);
    end
end 

The first part works fine, I get an error for the second part which says that the index exceeds array bounds for mod_MulInverse(i)=W(1) line.

Please help me understand the issue here and resolve the error.

Thank you !

Answer 1

[Sudharsana Iyengar]

Can you check the Size of W. and see what W(1) contains.

mod_MulInverse(i)=Column1(i); %working
mod_MulInverse(i)=W(1);% not working Are you sure for all values you want to store W(1) only.