That does it! I never would have guessed that dims would refer to the side length of the matrix. Thanks a ton.
On Wednesday, June 18, 2014 11:47:47 PM UTC-7, Alex wrote: > > Hi Ethan, > > irfft and brfft take an additional argument d, which roughly speaking > denotes the size of the transformed matrix. See also the docs on brfft > and irfft > <http://julia.readthedocs.org/en/latest/stdlib/base/?highlight=brfft#Base.brfft> > > The following should work for you > julia> a = rand(64, 64); > > julia> a_from_rfft = rfft(a); > > julia> back_to_a = irfft(a_from_rfft, size(a,1)); > > julia> norm(back_to_a-a) > 5.185263941656865e-15 > > Hope that helps, > > Alex. > > On Thursday, 19 June 2014 06:37:38 UTC+2, Ethan Anderes wrote: >> >> Does anyone have experience with brfft or irfft? I’m trying to optimize >> some code and I noticed a huge performance gain if I use rfft over fft for >> 2-d real matrices. However >> I need to filter in the Fourier domain, then use irfft (or brfft) to >> return to spatial corridinates but I can’t seem to get irfft or brfft to >> work. >> >> a = rand(1024, 1024); >> >> a_from_fft = fft(a); >> a_from_rfft = rfft(a); >> >> ### each one of these gives an error >> back_to_a = brfft(a_from_fft); >> back_to_a = brfft(a_from_rfft); >> back_to_a = irfft(a_from_fft); >> back_to_a = irfft(a_from_rfft); >> >> Here is my version info >> >> julia> versioninfo() >> >> Julia Version 0.3.0-prerelease+3730 >> Commit 8f1fbec (2014-06-17 23:55 UTC) >> Platform Info: >> System: Darwin (x86_64-apple-darwin13.2.0) >> CPU: Intel(R) Core(TM) i5-4250U CPU @ 1.30GHz >> WORD_SIZE: 64 >> BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY) >> LAPACK: libopenblas >> LIBM: libopenlibm >> >> >> >
