Index exceeds array bounds for nested for loop

As I am running the loop separately for a limited values, it is given the correct result. The moment i add a nested for loop, it shows an error stating "Index Exceeds array bounds". Data file is attached along with this.

For the reference, i am attaching the code:

datafile= importdata('abc.txt') %input data file
x=20; %total number of elements to be considered in one slot
g= ones(x,1)/x; %unit sample response
i=x; %initial value
len=193; %total number of elements in data file
z=datafile.^3; %cube of data present in file
s=zeros(x,1) %initialise sum as 0
for i = x:len-1   %Loop to calculate sum
     for j = i-x+1:i
        r(j) = z(j)* g(j); 
        s(i) = s(i)+r(j);
     end
 end

Answer 1

[KALYAN ACHARJYA]

j=i-x+1:i

firse case of for loop

i=x:len-1

where x=20, which is i first iterate value

Next loop

j =i-x+1:i

So

 j=20-20+1:i
>> j=1:i

Where

i=x:len-1 

Everytime j length changes depends on i, confusing

>> x=20; %total number of elements to be considered in one slot
g= ones(x,1)/x; %unit sample response
>> length(g)
ans =
    20

The length of g is 20, but you iterrate the code beyond that limit for g, how it get the respective value

    r(j) = z(j)* g(j); 
    %..............^

Please ensure for z too.

when for loop iterate

j=1, z(1) ok

j=2: z(2) ok

....

.....

if somehow j=21, z(21) is not avaliable

Please ensure the case, to avoid the error

[shona sharma]

All values of z are available and I have changed g= ones(len,1)/x ,but still it is showing the same error for s(i) = s(i)+r(j)

[KALYAN ACHARJYA]

Comment on Initial code:

At first look code seems mess,please explain what you are trying to do on abc file?

first for loop 2nd iteration when i=21

Second for loop

j=i-x+1:i

which becomes

j=21-20+1:21
j=2:21
%....^ then g(21) is not avaliable

Requested you to read array indexing.

[KALYAN ACHARJYA]

Are you looking for this one, no error please check the result- I have changed g and s, length(datafile), it result 193, same as len s you mentioned

datafile= importdata('abc.txt'); %input data file
x=20;  %total number of elements to be considered in one slot
g=ones(length(datafile),1)/x; %unit sample response
i=x; %initial value
z=datafile.^3; %cube of data present in file
s=zeros(length(datafile),1); %initialise sum as 0
r=[]; % Preallocation recomended
s=[];
for i=x:length(datafile)-1   %Loop to calculate sum
     for j=i-x+1:i
        r(j)=z(j)* g(j); 
        s(i)=s(i)+r(j);
     end
 end

[KALYAN ACHARJYA]

Please do confirm?