# How can I implement this equation?

**URL:** <https://discourse.julialang.org/t/how-can-i-implement-this-equation/61420>\
**Category:** New to Julia\
**Tags:** question\
**Created:** [May 19, 2021, 8:15am UTC](https://discourse.julialang.org/t/how-can-i-implement-this-equation/61420 "2021-05-19T08:15:36Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![assia855](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/assia855/32/22845_2.png) [@assia855](https://discourse.julialang.org/u/assia855)\
**Post date:** [May 19, 2021, 8:15am UTC](https://discourse.julialang.org/t/how-can-i-implement-this-equation/61420/1 "2021-05-19T08:15:36Z")

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Hello Forks

How can I implement P = A’\*D ?

```julia
typeof(A)=LazyAlgebra.Composition{3,Tuple{LazyAlgebra.Inverse{LazyAlgebra.FFTs.FFTOperator{Float64,2,Complex{Float64},FFTW.rFFTWPlan{Float64,-1,false,2,UnitRange{Int64}},FFTW.rFFTWPlan{Complex{Float64},1,false,2,UnitRange{Int64}}}},LazyAlgebra.NonuniformScaling{Array{Complex{Float64},2}},LazyAlgebra.FFTs.FFTOperator{Float64,2,Complex{Float64},FFTW.rFFTWPlan{Float64,-1,false,2,UnitRange{Int64}},FFTW.rFFTWPlan{Complex{Float64},1,false,2,UnitRange{Int64}}}}}

typeof(D)=Array{Float64,3}

```

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<div class="post-metadata">

**Author:** ![lmiq](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/lmiq/32/18314_2.png) [@lmiq](https://discourse.julialang.org/u/lmiq)\
**Post date:** [May 19, 2021, 12:46pm UTC](https://discourse.julialang.org/t/how-can-i-implement-this-equation/61420/2 "2021-05-19T12:46:53Z")

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Where does that `A` come from?

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<div class="post-metadata">

**Author:** ![assia855](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/assia855/32/22845_2.png) [@assia855](https://discourse.julialang.org/u/assia855)\
**Post date:** [May 19, 2021, 1:24pm UTC](https://discourse.julialang.org/t/how-can-i-implement-this-equation/61420/3 "2021-05-19T13:24:46Z")

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from a PSF file

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<div class="post-metadata">

**Author:** ![Skoffer](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/skoffer/32/378_2.png) [@Skoffer](https://discourse.julialang.org/u/Skoffer)\
**Post date:** [May 19, 2021, 1:44pm UTC](https://discourse.julialang.org/t/how-can-i-implement-this-equation/61420/4 "2021-05-19T13:44:03Z")

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It would be nice, if you can provide minimal working example, so people can reproduce your problem locally and give you reasonable answer.

Please read this topic [Please read: make it easier to help you](https://discourse.julialang.org/t/psa-make-it-easier-to-help-you/14757)