search for: mvfft

...his message is in MIME format --_=XFMail.1.3.p0.Linux:990422185944:4782=_ Content-Type: text/plain; charset=us-ascii R-0.64.0 on RedHat Linux 5.1 Some problems with multivariate fast fourier transform. I have attached the dump of a 30 x 3 matrix that seems to reliably reproduce these problems 1) mvfft doesn't like vectors. It complains about not having enough memory: R> mvfft(xx[,1]) Error: heap memory (2048 Kb) exhausted [needed 1024 Kb more] See "help(Memory)" on how to increase the heap size. What in fact is happening here is that do_mvfft tries to get the dimensi...

...his message is in MIME format --_=XFMail.1.3.p0.Linux:990422185944:4782=_ Content-Type: text/plain; charset=us-ascii R-0.64.0 on RedHat Linux 5.1 Some problems with multivariate fast fourier transform. I have attached the dump of a 30 x 3 matrix that seems to reliably reproduce these problems 1) mvfft doesn't like vectors. It complains about not having enough memory: R> mvfft(xx[,1]) Error: heap memory (2048 Kb) exhausted [needed 1024 Kb more] See "help(Memory)" on how to increase the heap size. What in fact is happening here is that do_mvfft tries to get the dimensi...

Hi All, I found "mvfft" in R and "fft2" in Matlab give different result and can't figure out why. My example is: In R: > matrix(c(1,4,2,20), nrow=2) [,1] [,2] [1,] 1 2 [2,] 4 20 > mvfft(matrix(c(1,4,2,20), nrow=2)) [,1] [,2] [1,] 5+0i 22+0i [2,] -3+0i -18+0i In Matlab:...

...ooking for a method to convolve it with a matrix. If I understood the docs for convolve correctly, it only works in 1D (and I have tried to convolve, it didn't look good). So, I wondered if anybody have implemented 2D convolution in R, or have any good advices to share (beyond having a look at mvfft), before I go hacking? Best, Kjetil -- Kjetil Kjernsmo Graduate astronomy-student Problems worthy of attack University of Oslo, Norway Prove their worth by hitting back E-mail: kjetikj at astro.uio.no - Piet Hein Homepage <URL:http:...

.../R-1.7.0/tests' make: *** [check] Error 2 this is the part in reg-tests-1.Rout.fail which fails: > ## fft > set.seed(123) > eps <- 1e-11 > for(N in 1:130) { + x <- rnorm(N) + if(N %% 5 == 0) { + m5 <- matrix(x,ncol=5) + stopifnot(apply(m5,2,fft) == mvfft(m5)) + } + dd <- Mod(1 - (f2 <- fft(fft(x), inverse=TRUE)/(x*length(x)))) + stopifnot(dd < eps) + } Any help concerning this matter would be very much appreciated. Best regards, James Reid.

...cy-bin, which the periodogram appears to do. However, if you look in various textbooks, the definition of the Fourier Transform (FT) varies from author to author in the magnitude of the prepended scaling factor. Since the periodogram is related to the FT (periodogram ultimately uses the function mvfft), without examination of the code for periodogram you cannot know the scaling factor, which is almost always one of the following: 1.0 1/2 1/(2*pi) SQRT(1/2) SQRT(1/(2*pi)) In fact, if you obtain an FT (or FFT or DFT) from a piece of electronics (say an electronic spectrum analyzer), th...

...= 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(x)) { for (j in i:ncol(x)) { # N0 = #{non-0-padded} pgram[, i, j] <- xfft[, i] * Conj(xfft[, j])/(N0*xfreq) ## value at zero is invalid as mean has been removed, so interpolate:...

...rgument. "log2" and "log10" are implemented this way. o "atan" can now either be invoked as atan(x) or atan(x,y). o The behavior of "fft" has been modified to match that of S (i.e. it returns a complex value. There is also a function "mvfft" which performs a "vector transform" when passed a matrix (i.e. it applies the fft to each column, rather than doing a 2d spatial transform). o A new functon "polyroot" can be used to find the roots of polynomials with (real or) complex coefficients. o Ve...

...rgument. "log2" and "log10" are implemented this way. o "atan" can now either be invoked as atan(x) or atan(x,y). o The behavior of "fft" has been modified to match that of S (i.e. it returns a complex value. There is also a function "mvfft" which performs a "vector transform" when passed a matrix (i.e. it applies the fft to each column, rather than doing a 2d spatial transform). o A new functon "polyroot" can be used to find the roots of polynomials with (real or) complex coefficients. o Ve...

...rgument. "log2" and "log10" are implemented this way. o "atan" can now either be invoked as atan(x) or atan(x,y). o The behavior of "fft" has been modified to match that of S (i.e. it returns a complex value. There is also a function "mvfft" which performs a "vector transform" when passed a matrix (i.e. it applies the fft to each column, rather than doing a 2d spatial transform). o A new functon "polyroot" can be used to find the roots of polynomials with (real or) complex coefficients. o Ve...

...cy-bin, which the periodogram appears to do. However, if you look in various textbooks, the definition of the Fourier Transform (FT) varies from author to author in the magnitude of the prepended scaling factor. Since the periodogram is related to the FT (periodogram ultimately uses the function mvfft), without examination of the code for periodogram you cannot know the scaling factor, which is almost always one of the following: 1.0 1/2 1/(2*pi) SQRT(1/2) SQRT(1/(2*pi)) In fact, if you obtain an FT (or FFT or DFT) from a piece of electronics (say an electronic spectrum analyzer), th...

...nt anymore. 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()...

...nt anymore. 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()...

R-1.7.0 built on NetBSD 1.6, but the validation test suite failed: Machinetype: Intel Pentium III (600 MHz); NetBSD 1.6 (GENERIC) Remote gcc version: gcc (GCC) 3.2.2 Remote g++ version: g++ (GCC) 3.2.2 Configure environment: CC=gcc CXX=g++ LDFLAGS=-Wl,-rpath,/usr/local/lib make[5]: Entering directory `/local/build/R-1.7.0/src/library' >>> Building/Updating