explain if i <=(len-sm) memg(j)=sum(semg(i:i+(sm-1)))/sm; else k=k+1 memg(j)=sum([semg(1:(sm-k))' semg(len-sm:(len-sm)+k-1)'])/sm; in matlab

This code is written in MATLAB and aims to calculate the Moving Average over a Signal. A moving average is commonly used in signal processing to smooth out noise in the data.

The input signal is 'semg', and the output signal is 'memg.' The variables 'i' and 'j' are loop variables in the code. The variables 'k' and 'sm' are both integers with 'sm' indicating the size of the moving window, and 'k' is the count of the number of data points that are removed from the beginning of the signal, and added to the end of the signal to complete the calculation.

In the first line, it checks whether the value of the loop variable 'i' is less than or equal to the difference of the length of the signal and the window size 'sm'. If it is not, then it moves to the else statement.

In the else statement, it increments the variable 'k' by 1 and calculates the moving average. The moving average to be calculated is the average of the first 'sm-k' positions and the last 'k' positions in the 'semg' signal.

Here's the explanation of the code in a simplified way:

main.m
if i <= (len-sm)
    % if i is less than or equal to the length of the signal minus the window size,
    % calculate the moving average using i:i+(sm-1)
    memg(j) = sum(semg(i:i+(sm-1))) / sm;
else
    % if i is greater than the length of the signal minus window size,
    % increment k by 1
    k = k + 1;
    % calculate the moving average using the first sm-k positions and the last k positions 
    memg(j) = sum([semg(1:(sm-k))' semg(len-sm:(len-sm)+k-1)']) / sm;
end
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