how can i generate a White Gaussian Noise in Matlab 2009
in [Matlab]
|
Prev: A begginer's question - ButtonDownFcn
Next: load figure and then save with original figure's color??
From: us on 26 May 2010 17:24 Walter Roberson <roberson(a)hushmail.com> wrote in message <JpaLn.17955$h57.156(a)newsfe22.iad>... > Artur Racu wrote: > > > it is ok...but you know then the chief want that the mean to be zero it > > is very hard to convience him that this answer is good > > So subtract off the mean that you do get, and the result will be have a > mean of 0 (to within round-off error.) walter the magician... that's exactly IT... us
From: Artur Artur on 26 May 2010 17:34 Ken <ken.colwell(a)gmail.com> wrote in message <cbca5506-8ca7-4458-8454-8e305aac654a(a)r9g2000vbk.googlegroups.com>... > > In theory, the mean of a set of numbers generated using RANDN will be 0. > > In practice, it won't. > > Here's a smaller example that may convince your chief that expecting exactly > > the theoretical result in practice is not always a good idea. > > > > Take a six-sided die and roll it once. The mean value of the "sequence" of > > numbers generated by that roll is whatever number came up on the die -- but > > the theoretical mean is 3.5. That's not achievable with one roll of that > > standard die. Even if you choose to roll that die a large odd number of > > times, you will never be able to achieve the theoretical mean of that number > > of rolls as all the numbers on the die are integers. > > > > If that argument doesn't work, then point him to Wikipedia (particularly the > > second example on this page): > > > > http://en.wikipedia.org/wiki/Law_of_averages > > > > If nothing else that should occupy him for a few hours following links to > > interesting topics :) > > > > -- > > Steve Lord > > sl...(a)mathworks.com > > comp.soft-sys.matlab (CSSM) FAQ:http://matlabwiki.mathworks.com/MATLAB_FAQ > > To contact Technical Support use the Contact Us link onhttp://www.mathworks.com > > > hey, > > just to have fun being technical: > > in theory, the mean of a set of numbers generated using randn *is a > random variable with a distribution centered at zero*, whose standard > deviation tightens as you increase the size of the set. in the limit > of infinite numbers in the set, the probability density function > becomes a delta function at zero (probability 1). > > wouldn't be worth mentioning except you're implying a difference > between theory and practice that doesn't exist. actually, in theory, > you will NEVER get exactly zero with a finite set of numbers (because > you're integrating the probability density function "from zero to > zero"). > > artur: the true statement would be "for white noise, the EXPECTED mean > is zero." also, if I'm understanding you right re: "gaussian curve > values", use normpdf() or mvnpdf(). ok merci for this...but finaly how can i generate a white gaussian noise in matlab version 2009, becouse in this version i don't have the function WGN or AWGN thnak you, Artur
From: Bruno Luong on 26 May 2010 17:38 ... If mean(randn(10,1)) is 0 (as Artur's boss claim), then mean(randn(9,1)) should also be 0 (why not), etc, ... ... mean(randn(2,1)) is also 0 mean(randn(1,1)) is also 0, therefore randn(1,1) would be 0 (I hope you still follow). Conclusion any Gaussian random process is a 0-delta function. Statistics would be easy like a toy game. Any noise vanishes, all measurement are infinity accurate, good does not play dice, the world will be perfect, and the peace is for all. I say no one can fire Artur's boss. Bruno
From: Artur Artur on 26 May 2010 17:38 TideMan <mulgor(a)gmail.com> wrote in message <d34de8f8-c5f2-4b8c-ba8f-0e03707ab1a9(a)s1g2000prf.googlegroups.com>... > I think I've come up with the perfect sop for Artur's boss who doesn't > like the mean of 10 random numbers not being exactly zero. > round(mean(randn(10,1))) for me this are just truckies(becouse it doesn't met the white noise definition)
From: Artur Artur on 26 May 2010 17:41
"Bruno Luong" <b.luong(a)fogale.findmycountry> wrote in message <htk4bs$ivo$1(a)fred.mathworks.com>... > .. If mean(randn(10,1)) is 0 (as Artur's boss claim), > then mean(randn(9,1)) should also be 0 (why not), > etc, ... > .. > mean(randn(2,1)) is also 0 > mean(randn(1,1)) is also 0, therefore randn(1,1) would be 0 (I hope you still follow). > > Conclusion any Gaussian random process is a 0-delta function. Statistics would be easy like a toy game. Any noise vanishes, all measurement are infinity accurate, good does not play dice, the world will be perfect, and the peace is for all. > > I say no one can fire Artur's boss. > > Bruno nice nice Bruno :) |