anyone pls give me a detailed description of what this code is doing ??? thxx

t=0 : 0.1: 30; x=10*sin (2*pi.*t/20);

figure;plot(t,x,'k','linewidth',2); xlabel('time,s'); ylabel('amplitude');

n=randn(size(t)); xn=x+n;

hold on; plot (t,xn);

wn=-5 : 1 : 5;

xc=xn;

for i = 6 : 1 : length(t) - 5

xc(i) = mean(xn(i + wn));

end

hold on; plot(t,xc,'q','linewidth',2);

[Andrew Newell]

Run one line at a time. See what it does. And look at the documentation, e.g., "doc randn".

[Oleg Komarov]

And format the code with teh code button for improved readability of your post.

Answer 1

[Oleg Komarov]

As Andrew suggested, use doc 'functioname' to understand with more details:

Generate a row vector with numbers going from 0 to 30 with 0.1 intervals

t = 0 : 0.1: 30;

Multiply each number in t by a tenth of pi (3.1415...), take the sin of the result an multiply again by 10.

y = 10*sin(t * pi/10); % same as x = 10*sin (2*pi.*t/20);

Plot values with black line ('k') adding labels

plot(t,y,'k','linewidth',2); 
xlabel('time,s'); 
ylabel('amplitude');

Generate a vector the same size as t with numbers distributed as a standard normal (white noise)

n = randn(size(t));

Add noise to y

yn = y+n;

Plot on the same axes

hold on; 
plot (t,yn);

Generate moving average with windowsize of 11. Very weird way to do it and in my opinion WRONG at the edges Generate wn (window positions)

wn = -5:5; % same as -5:1:5; default interval is always 1

Preallocate yc by copying yn

yc = yn;

Generate running average with windowsize of 11: for each number from 6 to the length of t minus 5 elements repeat the loop incrementing the counter "i" by 1 each time.

for i = 6:length(t) - 5 % same as 6:1:length(t) - 5
    % Take wn and add i.
    % The first run would be [-5 -4 -3 -2 -1  0  1  2  3  4  5] + 1 = 1:11!
    % So take values from yn which are positioned from 1:11 and average them
    % storing them in position i of yc
    yc(i) = mean(yn(i + wn));
end

More elegant way to generate moving average

wn = 11;
ycc = filter(ones(1,wn)/wn,1,yn);

Add running average to plot

% hold on;  no need, just call it once and call it off with hold off
plot(t,yc,'r','linewidth',2); % 'q' as colour doesn't exist replaced with red
plot(t,ycc,'g','linewidth',2); % you can also cutoff the initial 10 values of the moving average