# DoubleFloats plans for fft
**URL:** https://discourse.julialang.org/t/doublefloats-plans-for-fft/53921
**Category:** Numerics
**Created:** [January 25, 2021, 5:35pm UTC](https://discourse.julialang.org/t/doublefloats-plans-for-fft/53921 "2021-01-25T17:35:05Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@Jaime\_Araneda](https://discourse.julialang.org/u/Jaime_Araneda)
#### Post date: [January 25, 2021, 5:35pm UTC](https://discourse.julialang.org/t/doublefloats-plans-for-fft/53921/1 "2021-01-25T17:35:05Z")
Hi,
I would like to use fft’s under DoubleFloats. Is it possible to use plans to optimize the calculations?
Many thanks!
Jaime
---
### Author:  [@roflmaostc](https://discourse.julialang.org/u/roflmaostc)
#### Post date: [January 25, 2021, 6:28pm UTC](https://discourse.julialang.org/t/doublefloats-plans-for-fft/53921/2 "2021-01-25T18:28:51Z")
Yes, it is possible to do so. DoubleFloat is called `Float64`:
```julia
julia> x = randn((10, 6))
10×6 Array{Float64,2}:
0.677066 -0.751123 0.411206 -0.144039 -0.888348 -0.0769508
-0.945243 -0.669601 -1.491 -0.544662 1.27262 0.136143
0.28446 -0.723543 -0.160361 1.16289 0.23427 -0.607768
-0.234152 0.384269 -2.07268 -0.403732 -1.13892 1.14722
-0.521411 -0.25495 -0.491467 0.552317 -0.794891 1.13252
2.64284 -1.41663 -0.889482 0.192952 -0.102239 0.285883
0.433473 0.119091 -0.127861 0.107863 0.423339 0.575146
-0.430365 2.01674 1.17148 -0.515649 -0.614735 0.778848
0.414355 0.75615 -0.684232 -0.515438 -1.12986 -0.208387
-0.945138 -1.38633 -0.0074715 -0.395333 0.229893 -0.182433
julia> using FFTW
julia> p = plan_fft(x)
FFTW forward plan for 10×6 array of Complex{Float64}
(dft-rank>=2/1
(dft-direct-10-x6 "n2fv_10_avx2_128")
(dft-direct-6-x10 "n1fv_6_avx2_128"))
julia> p * x
10×6 Array{Complex{Float64},2}:
-4.92339+0.0im 5.83122+5.83627im 3.77128+2.66141im -6.02632+0.0im 3.77128-2.66141im 5.83122-5.83627im
-6.79686+3.87239im 1.81164+1.4843im -3.80074-5.21342im 3.99578+3.07849im -1.85259-2.79249im -11.3733+2.56027im
-0.34439-5.93107im -0.623183+6.69577im 1.07565+4.31514im 9.26973-4.32148im 7.85852-1.60115im -1.15141-3.45542im
1.41788-0.469272im 0.0864065-5.51548im -6.83544+5.2453im -7.50708+4.00053im -5.44799+0.380456im 3.21576+2.04184im
2.65891+4.59058im 8.8873-9.56459im 3.1661+1.12184im 3.14579+3.08435im 9.54174-2.81019im 2.18611-1.65011im
3.33042+0.0im -2.41414-4.85566im 4.37983+2.13933im -0.0617635+0.0im 4.37983-2.13933im -2.41414+4.85566im
2.65891-4.59058im 2.18611+1.65011im 9.54174+2.81019im 3.14579-3.08435im 3.1661-1.12184im 8.8873+9.56459im
1.41788+0.469272im 3.21576-2.04184im -5.44799-0.380456im -7.50708-4.00053im -6.83544-5.2453im 0.0864065+5.51548im
-0.34439+5.93107im -1.15141+3.45542im 7.85852+1.60115im 9.26973+4.32148im 1.07565-4.31514im -0.623183-6.69577im
-6.79686-3.87239im -11.3733-2.56027im -1.85259+2.79249im 3.99578-3.07849im -3.80074+5.21342im 1.81164-1.4843im
```
---
### Author:  [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)
#### Post date: [January 25, 2021, 6:34pm UTC](https://discourse.julialang.org/t/doublefloats-plans-for-fft/53921/3 "2021-01-25T18:34:48Z")
I believe this answer was asking about [https://github.com/JuliaMath/DoubleFloats.jl](https://github.com/JuliaMath/DoubleFloats.jl) which lets you use 2 `Float64` values to get 106 bits of precision.
---
### Author:  [@Jaime\_Araneda](https://discourse.julialang.org/u/Jaime_Araneda)
#### Post date: [January 25, 2021, 6:48pm UTC](https://discourse.julialang.org/t/doublefloats-plans-for-fft/53921/5 "2021-01-25T18:48:47Z")
Thanks to both for the quick responses. In fact, I’m interested in the extended precision of the DoubleFloats.jl package for intensive use of fft’s.
---
### Author:  [@roflmaostc](https://discourse.julialang.org/u/roflmaostc)
#### Post date: [January 25, 2021, 6:52pm UTC](https://discourse.julialang.org/t/doublefloats-plans-for-fft/53921/6 "2021-01-25T18:52:24Z")
Ah, my bad 😄
I did some digging and found [this](https://github.com/JuliaApproximation/FastTransforms.jl/pull/64)
```julia
julia> using FastTransforms
[Info: Precompiling FastTransforms [057dd010-8810-581a-b7be-e3fc3b93f78c]
julia> y = randn(Double64, (10, 10))
10×10 Array{Double64,2}:
-1.1292438537972538 -0.647511331823632 -0.2647247666637986 0.8267851456602784 1.3436907644238494 … 0.7870741156168397 -0.5287937843738052 -1.7250231675101182 0.22126096156067945
-0.15273201413073784 -0.8364645453039026 -0.3183729145601668 0.1417536736000426 0.45278025346723316 0.024227483743503867 -1.8280541794695537 0.6832412686365034 2.6330390741383765
0.5175505803284906 -0.7712969432337178 1.7893287272380964 0.20968617567882064 -0.8037639454510728 -0.8795971595690645 1.2002587197933383 -1.3769192958710266 -0.23218509952117508
0.3420447623467037 -1.2947623508838697 0.9307795811697627 0.6930611601306795 -0.9575991427231448 -0.14592052089972013 -0.37164316683469606 1.21693888457782 -0.8967976966654317
0.9704747983489629 1.8878756588207026 0.06305727124057722 0.9347732838576301 0.9292087926322615 0.6244744627146146 -0.046449033226453836 -0.540522799434064 0.7538986770485111
0.23960443387373154 -0.422600572244826 -1.3726986665291663 0.7188112112995776 0.5217224731263702 … -1.6025451241555402 1.2965817372108346 0.5117009222713786 1.1623435460649825
0.3631076668323081 -0.7390915858991868 -0.3147547733945754 -0.1762223496000308 -0.07734824598088659 -0.2755406866796454 0.5123448164121102 -0.07455447431286513 0.7240734073223415
0.260055557859319 -1.1021593352447352 -2.5449183044042556 -0.19074471493717693 1.6923292561435175 0.2735904232122618 -2.281275342839853 1.3632409182772423 -1.9103471623634534
-0.5463619527005806 1.8161824155649817 1.1298995223938033 1.0542431660455265 0.9549014407743441 2.101138912912026 0.8617700339970756 -0.8200795498955755 0.7172978226782473
-0.7380548662201147 -0.2868621636604453 1.0579940531814318 -0.9202852647999166 -0.8229624674270529 -0.04375364493708027 0.4492518422187647 -0.27399827842307145 -1.06797450208141
julia> fft(y)
ERROR: MethodError: no method matching generic_fft(::Array{Complex{Double64},2})
Closest candidates are:
generic_fft(::Array{T,1}) where T<:Union{AbstractFloat, Complex{T} where T<:AbstractFloat} at /home/fxw/.julia/packages/FastTransforms/oQJQJ/src/fftBigFloat.jl:11
Stacktrace:
[1] *(::FastTransforms.DummyFFTPlan{Complex{Double64},false}, ::Array{Complex{Double64},2}) at /home/fxw/.julia/packages/FastTransforms/oQJQJ/src/fftBigFloat.jl:198
[2] fft(::Array{Complex{Double64},2}, ::UnitRange{Int64}) at /home/fxw/.julia/packages/AbstractFFTs/mhQvY/src/definitions.jl:51
[3] fft(::Array{Double64,2}, ::UnitRange{Int64}) at /home/fxw/.julia/packages/AbstractFFTs/mhQvY/src/definitions.jl:198 (repeats 2 times)
[4] top-level scope at REPL[22]:1
[5] run_repl(::REPL.AbstractREPL, ::Any) at /build/julia/src/julia-1.5.3/usr/share/julia/stdlib/v1.5/REPL/src/REPL.jl:288
```
For some reason their latest package doesn’t support it anymore
---
### Author:  [@Jaime\_Araneda](https://discourse.julialang.org/u/Jaime_Araneda)
#### Post date: [January 25, 2021, 9:33pm UTC](https://discourse.julialang.org/t/doublefloats-plans-for-fft/53921/7 "2021-01-25T21:33:26Z")
If you take a slice it works:
julia\> using FFTW, FastTransforms, DoubleFloats
julia\> y = Double64.(randn(10,10));
julia\> fft(y[:,1])
10-element Array{Complex{Double64},1}:
-0.5997902658636178 + 4.622231866529366e-33im
-3.925995047597333 + 0.4632874725753252im
-2.344821026447533 - 1.1174059973165642im
0.9948184949863303 + 1.5537872960816208im
-6.429590723078108 + 0.05469385542831158im
-2.2804314503074674 + 2.04107518113366e-33im
-6.429590723078108 - 0.05469385542831158im
0.9948184949863303 - 1.5537872960816208im
-2.344821026447533 + 1.1174059973165642im
-3.925995047597333 - 0.4632874725753252im