search for: nextn

...er > > Herve> (a length of 2^n is the best case for the fft, the worst case > being > when > > Herve> the length is a prime number): > ... > > The typical approach here and definitely the idea of the > > original author of convolve() - would be to use nextn() here > > instead of "next_power_of_2()". > > The current implementation of convolve uses an fft-buffer of length > nx + ny - 1 for "open" convolution, not nextn(). > The fft-based convolution is by nature "circular". However it can be > used fo...

...ipating seeing a spike at 10Hz with the function 10* sin(2*pi*10*t). I can't figure out why my plots do not show spikes at the frequencies I expect. Am I doing something wrong or is my expectations wrong? require(stats) layout(matrix(c(1,2,3), 3, 1, byrow = TRUE)) #SETUP n <- 256 #nextn(1001) gives next power 2 F <- 100 #Hz -50 to 50 Hz dt <- 1/F T <- n*dt df <- 1/T t <- seq(0,T,by=dt) #also try ts function t<-t[1:length(t)-1] freq <- 5 #Hz #SIGNAL FUNCTION y <- 10* sin(2*pi*10*t) #10*sin(2*pi*freq*t) #FREQ ARRA...

Hi, I would like to know if there is a way to change a vector of arbitrary size to make it fits the nearest upper size multiple of a power of 2. -- Cordialy ---------------------------------------- Emmanuel POIZOT Cnam/Intechmer Digue de Collignon 50110 Tourlaville T?l : (33)(0)2 33 88 73 42 Fax : (33)(0)2 33 88 73 39 -----------------------------------------

...ot;, then length(x)+length(y)-1 should have many factors (e.g. length(x)+length(y)-1 = 2^n) In particular the latter may not be obvious to first time users, who may think that stats::convolve is slow, even though it is fast, if applied correctly. Moreover for zero padding, one may apply stats::nextn to (a) length(x) or (b) length(x)+length(y)-1. #Example: #correct usage: x <- rnorm(514289) y <- rnorm(10000) #length(x) + length(y) - 1 = 2^19 system.time(convolve(x, y, type="open")) # user system elapsed # 1.17 0.02 1.18 #incorrect usage: x <- rnorm(300000)...

Hi R-users: I want to know if there is an easy way to obtain a Fourier Transform form a vector or an array (just like fft does), but with a more density base. I mean, if I have a vector of 512 of length, I want the Fourier Transform to be 1024, or 2048, etc, in length (de u domain). Or should I modify the fft C code to do that? If I want to modify the precision of the fft function, which

...## to correct for tapering: Bloomfield (1976, p. 194) ## Total taper is taper*2 u2 <- (1 - (5/8)*taper*2) u4 <- (1 - (93/128)*taper*2) if (pad > 0) { x <- rbind(x, matrix(0, nrow = N * pad, ncol = ncol(x))) N <- nrow(x) } NewN <- if(fast) nextn(N) else N x <- rbind(x, matrix(0, nrow = (NewN - N), ncol = ncol(x))) N <- nrow(x) Nspec <- floor(N/2) freq <- seq.int(from = xfreq/N, by = xfreq/N, length.out = Nspec) xfft <- mvfft(x) pgram <- array(NA, dim = c(N, ncol(x), ncol(x))) for (i in 1L:ncol(...

...creased warning level. * Parse data now have deterministic parent nodes (PR#16041). * Calling match() with length one x and POSIXlt table gave a segfault (PR#17459). * Fork clusters could hang due to a race condition in cluster initialization (makeCluster()). * nextn(n) now also works for larger n and no longer loops infinitely for e.g, n <- 214e7. * cooks.distance() and rstandard() now work correctly for multiple linear models ("mlm"). * polym() and corresponding lm() prediction now also work for a boundary "vector...

...creased warning level. * Parse data now have deterministic parent nodes (PR#16041). * Calling match() with length one x and POSIXlt table gave a segfault (PR#17459). * Fork clusters could hang due to a race condition in cluster initialization (makeCluster()). * nextn(n) now also works for larger n and no longer loops infinitely for e.g, n <- 214e7. * cooks.distance() and rstandard() now work correctly for multiple linear models ("mlm"). * polym() and corresponding lm() prediction now also work for a boundary "vector...

...o chull() has been moved to package graphics (as it uses xy.coords). o There is now a coef() method for summaries of "nls" objects. o compareVersion(), packageDescription() and read.00Index() have been moved to package 'utils'. o convolve(), fft(), mvfft() and nextn() have been moved to package stats. o coplot() now makes use of cex.lab and font.lab par() settings. o cumsum/prod/max/min() now preserve names. o data(), .path.packages() and .find.packages() now interpret package = NULL to mean all loaded packages. o data.frame() and its rep...

...o chull() has been moved to package graphics (as it uses xy.coords). o There is now a coef() method for summaries of "nls" objects. o compareVersion(), packageDescription() and read.00Index() have been moved to package 'utils'. o convolve(), fft(), mvfft() and nextn() have been moved to package stats. o coplot() now makes use of cex.lab and font.lab par() settings. o cumsum/prod/max/min() now preserve names. o data(), .path.packages() and .find.packages() now interpret package = NULL to mean all loaded packages. o data.frame() and its rep...

...on operators did not warn about inconsistent lengths for real vectors, but did for integer, logical and character vectors. o spec.pgram(x, ..., pad, fast, ...) computed the periodogram with a bias (downward) whenever 'pad > 0' (non-default) or 'fast = TRUE' (default) and nextn(n) > n where n = length(x); similarly for 'df' (approximate degrees of freedom for chisq). o dgamma(0, a) now gives Inf for a < 1 (instead of NaN), and so does dchisq(0, 2*a, ncp). o pcauchy() is now correct in the extreme tails. o file.copy() did not check that any e...

...on operators did not warn about inconsistent lengths for real vectors, but did for integer, logical and character vectors. o spec.pgram(x, ..., pad, fast, ...) computed the periodogram with a bias (downward) whenever 'pad > 0' (non-default) or 'fast = TRUE' (default) and nextn(n) > n where n = length(x); similarly for 'df' (approximate degrees of freedom for chisq). o dgamma(0, a) now gives Inf for a < 1 (instead of NaN), and so does dchisq(0, 2*a, ncp). o pcauchy() is now correct in the extreme tails. o file.copy() did not check that any e...

.../R/library/base/R-ex/name.R action: create D: file: /usr/local/lib/R/library/base/R-ex/names.R action: create D: file: /usr/local/lib/R/library/base/R-ex/nargs.R action: create D: file: /usr/local/lib/R/library/base/R-ex/nchar.R action: create D: file: /usr/local/lib/R/library/base/R-ex/nextn.R action: create D: file: /usr/local/lib/R/library/base/R-ex/nhtemp.R action: create D: file: /usr/local/lib/R/library/base/R-ex/nlevels.R action: create D: file: /usr/local/lib/R/library/base/R-ex/nlm.R action: create D: file: /usr/local/lib/R/library/base/R-ex/noquote.R action: create...

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