# Does FFTW keep a system wisdom

**URL:** <https://discourse.julialang.org/t/does-fftw-keep-a-system-wisdom/4048>\
**Category:** General Usage\
**Tags:** fftw\
**Created:** [June 2, 2017, 12:00am UTC](https://discourse.julialang.org/t/does-fftw-keep-a-system-wisdom/4048 "2017-06-02T00:00:44Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![favba](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/favba/32/2735_2.png) [@favba](https://discourse.julialang.org/u/favba)\
**Post date:** [June 2, 2017, 12:00am UTC](https://discourse.julialang.org/t/does-fftw-keep-a-system-wisdom/4048/1 "2017-06-02T00:00:44Z")

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Does a Julia’s FFTW library keeps its own system wisdom?  
I use fft’s quite often for a given set of array dimensions. I’d like to create optimized plans (using FFTW.EXHAUSTIVE flag). I know how to export and import plans and have been doing that, creating wisdom files for the set of data I have on a given folder. But I end up with lots of different wisdoms files.

Basically, what I’d like to have is a ever increasing system wisdom that is always imported on every usage of fft. Is that what happens already?

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**Author:** ![stevengj](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stevengj/32/71_2.png) [@stevengj](https://discourse.julialang.org/u/stevengj)\
**Post date:** [June 2, 2017, 2:32am UTC](https://discourse.julialang.org/t/does-fftw-keep-a-system-wisdom/4048/2 "2017-06-02T02:32:34Z")

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No, no wisdom is imported/exported by default.

Note that you can always create a single wisdom file for your own use; I’m not sure why you are ending up with lots of wisdom files instead of using just one?

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**Author:** ![favba](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/favba/32/2735_2.png) [@favba](https://discourse.julialang.org/u/favba)\
**Post date:** [June 2, 2017, 4:24am UTC](https://discourse.julialang.org/t/does-fftw-keep-a-system-wisdom/4048/3 "2017-06-02T04:24:37Z")

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I guess it was due to my lack of understanding of how it works.  
So, I can just increment an already created wisdom file, is that it? I import the old wisdom, create the different plans I need and export it to the same file again, is that it?