search for: sinusoids

Displaying 20 results from an estimated 54 matches for "sinusoids".

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2012 Apr 09
0
Question on harmonic (Fourier) analysis of sinusoidal time series
Hello, I will try to explain the problem, sorry if it will be a little long... I'm using R to analyze results of cyclic mechanical testing, like this: - apply quasi-sinusoidal load - measure quasi-sinusoidal vertical and horizontal deformations (quasi-sinusoidal load means that load "should be" sinusoidal, but testing machine puts in some noise...) I enclose a sample of data at
2009 Oct 07
1
sinusoidal relationship
Hi, Suppose x and y are vectors whose elements are known. I know that there is a sinusoidal relation between them. In other words, y=a*sin(bx) where b is probably a function of pi. How do I find a and b in R? Hakan [[alternative HTML version deleted]]
2005 Jan 13
3
Problem encoding sine wave in 1.1.6 and somewhat in 1.0.4
On Thu, 2005-01-13 at 12:42 -0500, Jean-Marc Valin wrote: > Le jeudi 13 janvier 2005 ? 10:59 -0500, Jared Whitby a ?crit : > > Interestingly enough.. I started playing around with preprocessing > > options in 1.1.6 and happened upon the denoise filter > > (SPEEX_PREPROCESS_SET_DENOISE). When i run the test tone using that > > option it is completely filtered out and I
2009 Aug 10
1
manipulating text to generate different formulas to use in nls()
Hello, In doing a series of non-linear estimations of a function which is a sum of a varying number of sinusoids, I would like to "autogenerate" the arguments needed by nls() depending on that number. For example, when there are two sinusoids: > nls( y ~ mu + A1 * cos(2*pi*f1*x - P1) + A2 * cos(2*pi*f2*x - P2), data = some.xy.data, start = list( mu=some.value0, A1=some.value1,...
2008 Jan 25
2
Fourier Analysis and Curve Fitting in R
Dear List, I am attempting to perform a harmonic analysis on a time series of snow depth, in which the annual curve is essentially asymmetric (i.e. snow accumulates slowly over time, and the subsequent melt occurs relatively rapidly). I am trying to fit a curve to the data, however, the actual frequency is unknown. I have been trying to follow the methods in Peter Bloomfields text
2008 Oct 27
2
Stuck with FFT
Dear all, Before I can get into serious Fourier analysis of Radon time-series I am practising with 24hour and 24.8hour sinusoids to assist with my interpretation of signals ittributed to tidal input to Radon time series. I am stuck. I have tried researching this to no avail. I am awating a book that should describe fourier transforms in detail and another one that should discuss the R application. I know what the command l...
2008 Jan 10
3
Cycle Regression Analysis in R?
Hello R community, Does anyone know of a package that will perform cycle regression analysis? I have searched the R-help archives etc. but have come up with nothing so far. If I am unable to find an existing R package to do so, is there anyone familiar with fitting sine functions to data. My problem is this: I have a long time-series of daily SWE estimates (SWE = snow water equivalence, or
2005 Jan 13
0
Problem encoding sine wave in 1.1.6 and somewhat in 1.0.4
...I still think theres a bug lurking around in there. The denoiser just prevents it from ever making it to the encoder. Just from browsing through the speex code and from what I've learned reading through the mailing list, it looks like there are a few places where checks are in place to prevent sinusoids from destabilizing the stream. Somehow this particular sine wave is getting through the cracks I think. I actually tried a couple of lower frequency samples and It didn't seem to cause the problem I was having. But, I seem to be in good shape with the filter in place... so just figured I would...
2010 Apr 15
2
Regression using R
Hello, I'm working on a very large project in which we do many calculations which include many types of regression such as, Liner, Quadratic, Cubic, Exponential, Sinusoidal, and Logarithmic. Im well aware that its easy enough to do Linear regression in R but what about the other types? I've been searching on google for such functions but to no avail. Thank you, -- Samuel Bravo
2006 Dec 19
2
fit sine?
Hello list, I am making scatterplots of data that vary sinusoidally over 24 hours. With a bit of previous help from this list, I now can get an x-axis with time tics from 00:00 on the left edge to 12:00 in the middle and 00:00 on the right edge, i.e., just 24 hours. Now I would like to fit a sin function to the plot. I've looked all over CRAN and the web in general, but have not found a
2008 Jan 29
0
[Fwd: Re: Fourier Analysis and Curve Fitting in R]
...follow the methods in Peter Bloomfields text "Fourier Analysis of Time Series", but am having trouble implementing this in R. Yes it certainly would. Note that even though the ``actual frequency'' is (???) 1/(1 year), the representation of the mean function in terms of sinusoids will involve in theory infinitely many terms/frequencies since the mean function is clearly (!) not a sinusoid. Does anyone have any suggestions, or perhaps directions on how this might be done properly? Am I using the right methods for fitting an asymmetric curve? What I am really try...
2011 May 31
2
newbie: fourier series for time series data
Hi Guys, I had a monthly time series's data of land temperature from 1980 to 2008. After plotting a scatter diagram, it seems that annually, there is a semi sinusoidal cycle. How do I run Fourier's series to the data so that I can fit model on it? I am really sorry for my question sound stupid, but I just don't know where to start. I am desperately looking for help from you guys.
2002 Jul 26
5
Is there a function for finding local extrema.
I have a vector with about 100.000 values representing a quite regular function (sinusoid like). I would like to find all local maxima of this function (should be about 4000). Is there a native routine for R? Thanks in advance Eryk. -- _|_ \|/ \|/ Eryk Witold Wolski tel :0049-(0)30-8413-1543 w w ?v? 'v? \'v'/ MPI Moleculare Genetik fax :0049-(0)30-8413-1139 |
2008 Jun 04
2
estimate phase shift between two signals
Hi, Are there any functions in R that could be used to estimate the phase-shift between two semi-sinusoidal vectors? Here is what I have tried so far, using the spectrum() function -- possibly incorrectly: # generate some fake data, normalized to unit circle x <- jitter(seq(-2*pi, 2*pi, by=0.1), amount=pi/8) # functions defining two out-of-phase phenomena f1 <- function(x)
2006 Jan 28
3
Creating 3D Gaussian Plot
Hello, I requested help a couple of weeks ago creating a dipole field in R but receieved no responses. Eventually I opted to create a 3d sinusoidal plot and concatenate this with its inverse as a means for a "next best" situation. It seems that this isn't sufficient for my needs and I'm really after creating a continuous 3d gaussian mesh with a "positive" and
2005 Jan 13
2
Problem encoding sine wave in 1.1.6 and somewhat in 1.0.4
...nk both would reproduce the exact same > results. > > Jared > > On Tue, 11 Jan 2005 05:38:58 -0500, Jean-Marc Valin > <Jean-Marc.Valin@usherbrooke.ca> wrote: > > Hi, > > > > The first thing I should saw is that Speex isn't designed to handle > > sinusoids, although it shouldn't produce garbage. I checked the files > > you upload and I've had no problem with it. Are you using any particular > > setting? Of course, this is one example of a file for which you cannot > > seek unless you actually seek on the decoded signal. >...
2011 Apr 14
7
[OT] ups advice
Hi I have a Dell PowerEdge T310 *tower* server.. I have to buy an ups by apc... anyone could help me giving an hint ? a simple "smart ups 1000" could be enough ? thx so much!! lewis.
2008 Aug 15
1
map("state" ...) Is the USA cracking up?
Running R version 2.6.1 under Linux, I'm trying to use the maps and mapdata packages and the state database to produce a thematic map of the USA. My problem is that cracks (white spaces) appear between some states--e.g. between Colorado and Utah and between Michigan and Indiana. The resulting visual impression is that the country is breaking up. This occurs in all the projections I have
2009 Nov 01
1
problems whit seasonal ARIMA
Hello, I have daily wind speed data and need to fit seasonal ARIMA model, problem is that my period is 365. But when I use arima(...) function, with period 365, I?m getting error message: ?Error in makeARIMA(trarma[[1]], trarma[[2]], Delta, kappa) : maximum supported lag is 350?. Can someone help me with this problem? Thank you Sincerely yours, Laura Saltyte
2009 Nov 30
1
regression with a*cos(angle+phi)+b
Hello, the only thing I found to fit a sin/cos is s.th like lm(a~cos+sin) But this is not what I want. I have a magnitude which is sinusoidal with offset and it doesn't start at phi=0. The data is: angle<-c(0,10,20,30,40,50,60,70,80,90,100,110,120,130,140,150,160,170,180) Voltage<-c(-45.07, -45.24, -43.61, -40.78, -36.48, -30.92, -23.83, -15.95, -7.53, 1.06, 11.24,19.85, 27.00,