Index exceeds the number of array elements - Error message

Posted a similar question before, but this time it is for taking an average of every 2 data points. For example: 1 2 is averaged, 3 4 is averaged, 5 6, 7 8, etc. I am getting an error where n1 is larger than the array, which is giving the error in ma. Pretty sure I have to change the length but not sure how to go about it. What should I do?

Here is the code:

clear all

mdata = [1 2 3 4 5 6 7 8 9 10];
 
k = 1; 
n1 = 1;

for n = 1:length(mdata)
    ma(n) = (1/(k + 1)) * sum(mdata(n1:n1 + k));
    n1 = (n1 + k) + 1; 
    std_ma(n) = std(ma);
end

Error message:

Index exceeds the number of array elements (10).

Error in untitled29 (line 9)

ma(n) = (1/(k + 1)) * sum(mdata(n1:n1 + k));

Answer 1

[David Hill]

mdata = [1 2 3 4 5 6 7 8 9 10];
 
k = 1; 
c = 1;
for n1 = 1:2:length(mdata)
    ma(c) = (1/(k + 1)) * sum(mdata(n1:n1 + k));
    std_ma(c) = std(ma);
    c=c+1;
end

std_ma = 1×5

0 1.4142 2.0000 2.5820 3.1623

[zen]

What if I wanted to increase the averaging size from 2 to 3? I get the error again when I do that. for example:

mdata = [1 2 3 4 5 6 7 8 9 10];
 
k = 2; 
c = 1;
for n1 = 1:3:length(mdata)
    ma(c) = (1/(k + 1)) * sum(mdata(n1:n1 + k));
    std_ma(c) = std(ma);
    c = c + 1;
end

Index exceeds the number of array elements. Index must not exceed 10.

Answer 2

[Steven Lord]

x = 1:10

x = 1×10

1 2 3 4 5 6 7 8 9 10

y = reshape(x, 2, [])

y = 2×5

1 3 5 7 9 2 4 6 8 10

m = mean(y, 1) % mean of each column; "collapse" dimension 1 to size 1 by taking the mean

m = 1×5

1.5000 3.5000 5.5000 7.5000 9.5000

m2 = mean(y, 2) % "collapse" dimension 2 to size 1 by taking the mean

m2 = 2×1

5 6

All these assume that the number of elements in x is a multiple of 2. If it isn't the reshape call will error.

y2 = reshape([x, 11], 2, [])

Error using reshape
Product of known dimensions, 2, not divisible into total number of elements, 11.