# std

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## std

 hi, look that: >> vv=media(20:40) vv =     433.59     485.94     590.62     632.81     674.22     714.45     769.14     839.06     934.77     932.42     998.05    1058.59    1069.92    1005.08     923.44     835.16     727.34     618.36     471.88     360.94     269.53 i want to do std in 5 element: > std(vv,0,5) ans =    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0 Why i get this result? All zero -- Sent from: http://octave.1599824.n4.nabble.com/Octave-General-f1599825.html
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## Re: std

 On 5/17/19 2:41 PM, turbofib via Help-octave wrote: ```i want to do std in 5 element: ``` ```std(vv,0,5) ``` ```ans = 0 0 0``` 'help std' explains that the third argument to std() specifices the dimension along which you take the std(). Your data has just one dimension, so the result is zero. What do you want to calculate? what  do you mean by 'std in 5 element'?
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## Re: std

 hi, sorry but i don't understand.. look this example: 1 2 3 4 8 2,701851217 (stdev 5 last element) 6 2,408318916 (stdev 5 last element) 7 2,073644135 (stdev 5 last element) 8 1,673320053 (stdev 5 last element) 9 1,140175425 (stdev 5 last element) 10 1,58113883 (stdev 5 last element) this is result using excel.. (is not zero as octave give me :)   -- Sent from: http://octave.1599824.n4.nabble.com/Octave-General-f1599825.html
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## Re: std

 On Fri, May 17, 2019 at 17:11:21 -0500, turbofib via Help-octave wrote: > hi, > sorry but i don't understand.. > > look this example: > > 1 > 2 > 3 > 4 > 8 2,701851217 (stdev 5 last element) > 6 2,408318916 (stdev 5 last element) > 7 2,073644135 (stdev 5 last element) > 8 1,673320053 (stdev 5 last element) > 9 1,140175425 (stdev 5 last element) > 10 1,58113883 (stdev 5 last element) > > this is result using excel.. > > (is not zero as octave give me :) You are looking for the moving standard deviation, calculated over a sliding window.     >> lookfor "standard deviation"     movstd              Calculate the moving standard deviation over a s...     statistics          Return a vector with the minimum, first quartile...     std                 Compute the standard deviation of the elements o...     >> movstd (x, 5)     >> movstd (x, [4, 0]) -- mike signature.asc (849 bytes) Download Attachment
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## Re: std

 In reply to this post by Octave - General mailing list Hi, You need to get use to read the help of the functions. The third input argument of std indicates along which dimension the function will compute, that is 1 for "along columns", 2 for "along rows", 3 for "along pages" (in a 3D matrix), etc... We do not understand what you want to do with. If you explain what you mean by "5 elements" we can give better answers. From you example it seems you mean the std in the last 5 elements, that would be std (vv(end-4:end)) ans =  186.01 If you want std on a moving window of size 5 you can do movstd(data, 5) ans =     79.955     91.922    100.859     87.834     69.483     80.843    103.496     97.835     90.237     82.031     65.459     54.994     58.322     98.814    135.773    153.632    177.823    190.644    186.009    150.281    101.332
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## Re: std

 Your excel example would be movstd([1:4 8 6 7:10].',[4 0]) ans =    0.00000    0.70711    1.00000    1.29099    2.70185    2.40832    2.07364    1.67332    1.14018    1.58114