# Unknown error with norm() function

**URL:** <https://discourse.julialang.org/t/unknown-error-with-norm-function/36225>\
**Category:** New to Julia\
**Created:** [March 19, 2020, 8:15pm UTC](https://discourse.julialang.org/t/unknown-error-with-norm-function/36225 "2020-03-19T20:15:10Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![iamsuddhasattwa](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/iamsuddhasattwa/32/7441_2.png) [@iamsuddhasattwa](https://discourse.julialang.org/u/iamsuddhasattwa)\
**Post date:** [March 19, 2020, 8:15pm UTC](https://discourse.julialang.org/t/unknown-error-with-norm-function/36225/1 "2020-03-19T20:15:10Z")

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I am having trouble with using the basic norm() function after having loaded using LinearAlgebra; In the lines below, `Phi` is a matrix created in the middle of a larger program.

```julia
julia> typeof(Phi)
Array{Float64,2}
julia> x = Phi[:,1];
julia> typeof(x)
Array{Float64,1}
julia> norm(x)
ERROR: MethodError: objects of type Array{Float64,2} are not callable
Use square brackets [] for indexing an Array.
Stacktrace:
 [1] top-level scope at REPL[24]:1

```

Can anyone tell me what this error message means ? Thank you.

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<div class="post-metadata">

**Author:** ![rdeits](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/rdeits/32/286_2.png) [@rdeits](https://discourse.julialang.org/u/rdeits)\
**Post date:** [March 19, 2020, 8:21pm UTC](https://discourse.julialang.org/t/unknown-error-with-norm-function/36225/2 "2020-03-19T20:21:54Z")

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You have a local variable called `norm` which is a `Matrix{Float64}` (a.k.a. `Array{Float64, 2}`), so you are not calling the function `norm` but instead trying to use your Matrix named `norm` as if it were a function.

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<div class="post-metadata">

**Author:** ![iamsuddhasattwa](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/iamsuddhasattwa/32/7441_2.png) [@iamsuddhasattwa](https://discourse.julialang.org/u/iamsuddhasattwa)\
**Post date:** [April 14, 2020, 2:15pm UTC](https://discourse.julialang.org/t/unknown-error-with-norm-function/36225/3 "2020-04-14T14:15:32Z")

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Thank you very much !