# Error Nonlinear expressions may contain only scalar expressions

**URL:** <https://discourse.julialang.org/t/error-nonlinear-expressions-may-contain-only-scalar-expressions/82124>\
**Category:** Optimization (Mathematical)\
**Created:** [June 2, 2022, 12:26pm UTC](https://discourse.julialang.org/t/error-nonlinear-expressions-may-contain-only-scalar-expressions/82124 "2022-06-02T12:26:14Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![manoj.centura](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/manoj.centura/32/216443_2.png) [@manoj.centura](https://discourse.julialang.org/u/manoj.centura)\
**Post date:** [June 2, 2022, 12:26pm UTC](https://discourse.julialang.org/t/error-nonlinear-expressions-may-contain-only-scalar-expressions/82124/1 "2022-06-02T12:26:14Z")

</div>

```nohighlight
 countBM=6
 model= Model()
 @variable(model,x[i in 1:30])
 BendMom=Array{Any}(undef,countBM)
 zz=@NLexpression(model,[i in 1:30],x[i]+i)
 BendMom[1]=@NLexpression(model,zz+1)
julia> BendMom[1]=@NLexpression(model,zz+1)
ERROR: Unexpected array NonlinearExpression["Reference to nonlinear expression #1", "Reference to nonlinear expression #2", "Reference to nonlinear expression #3", "Reference to nonlinear expression #4", "Reference to nonlinear expression #5", "Reference to nonlinear expression #6", "Reference to nonlinear expression #7", "Reference to nonlinear expression #8", "Reference to nonlinear expression #9", "Reference to nonlinear expression #10", "Reference to nonlinear expression #11", "Reference to nonlinear expression #12", "Reference to nonlinear expression #13", "Reference to nonlinear expression #14", "Reference to nonlinear expression #15", "Reference to nonlinear expression #16", "Reference to nonlinear expression #17", "Reference to nonlinear expression #18", "Reference to nonlinear expression #19", "Reference to nonlinear expression #20", "Reference to nonlinear expression #21", "Reference to nonlinear expression #22", "Reference to nonlinear expression #23", "Reference to nonlinear expression #24", "Reference to nonlinear expression #25", "Reference to nonlinear expression #26", "Reference to nonlinear expression #27", "Reference to nonlinear expression #28", "Reference to nonlinear expression #29", "Reference to nonlinear expression #30"] in nonlinear expression. Nonlinear expressions may contain only scalar expressions.
```

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**Author:** ![blob](https://avatars.discourse-cdn.com/v4/letter/b/ebca7d/32.png) [@blob](https://discourse.julialang.org/u/blob)\
**Post date:** [June 2, 2022, 12:53pm UTC](https://discourse.julialang.org/t/error-nonlinear-expressions-may-contain-only-scalar-expressions/82124/2 "2022-06-02T12:53:43Z")

</div>

Your `zz` is a vector so you have to consider the elements one by one:

```julia
BendMom[1]=@NLexpression(model,[i in 1:30], zz[i]+1)

```

Explanation: [Nonlinear Modeling · JuMP](https://jump.dev/JuMP.jl/stable/manual/nlp/#Scalar-operations-only)