# How to pass Array{Array{Float64,1},1} to ccall double\*\*

**URL:** <https://discourse.julialang.org/t/how-to-pass-array-array-float64-1-1-to-ccall-double/18120>\
**Category:** General Usage\
**Tags:** question\
**Created:** [November 29, 2018, 12:06am UTC](https://discourse.julialang.org/t/how-to-pass-array-array-float64-1-1-to-ccall-double/18120 "2018-11-29T00:06:21Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![groot](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/groot/32/13081_2.png) [@groot](https://discourse.julialang.org/u/groot)\
**Post date:** [November 29, 2018, 12:06am UTC](https://discourse.julialang.org/t/how-to-pass-array-array-float64-1-1-to-ccall-double/18120/1 "2018-11-29T00:06:22Z")

</div>

For `double*`, I find it is easy to use `Ref{Cdouble}`. But for `double**`, when I use `Ref{{Ref{Cdouble}}}` and pass `Array{Array{Float64,1},1}` . It gives an error

MethodError: Cannot `convert` an object of type Array{Array{Float64,1},1} to an object of type Float64

What is the right way to pass this pointer? Thanks