# Assemble load line vector

**URL:** <https://discourse.julialang.org/t/assemble-load-line-vector/100575>\
**Category:** New to Julia\
**Tags:** question, gridap, integral\
**Created:** [June 19, 2023, 9:42pm UTC](https://discourse.julialang.org/t/assemble-load-line-vector/100575 "2023-06-19T21:42:56Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![mary](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mary/32/53139_2.png) [@mary](https://discourse.julialang.org/u/mary)\
**Post date:** [June 19, 2023, 9:42pm UTC](https://discourse.julialang.org/t/assemble-load-line-vector/100575/1 "2023-06-19T21:42:56Z")

</div>

hi, I want to integrate applied displacement on a load line and assemble the vector on my FE test space(V0\_Disp) but it gives me error. is there anyone who knows what should i do to solve this?

```julia
dirichlet_tags = ["LeftSupport","RightSupport","LoadLine"],
    dirichlet_masks =[(false ,true), (true ,true), (false ,true)])
uApp3 = VectorValue(0.0,-vAppMax)
labels = get_face_labeling(model)
LoadTagId = get_tag_from_name(labels ,"LoadLine")
Γ_Load = BoundaryTriangulation(model ;tags = LoadTagId)
dΓ_Load = Measure(Γ_Load ,degree)
b_vec = assemble_vector((v->∫(v)fem_params.dΓ_Load)∘ uApp3, fem_params.V0_Disp)

```

the error is

```julia
AssertionError: ndims(eltype(cell_vec)) == 1

Stacktrace:
 [1] collect_cell_vector(test::Gridap.FESpaces.UnconstrainedFESpace{Vector{Float64}, Gridap.FESpaces.NodeToDofGlue{VectorValue{2, Int32}}}, a::DomainContribution)
   @ Gridap.FESpaces C:\Users\marya\.julia\packages\Gridap\971dU\src\FESpaces\Assemblers.jl:420
 [2] assemble_vector(f::ComposedFunction{var"#242#243", typeof(uApp3)}, a::Gridap.FESpaces.GenericSparseMatrixAssembler, V::Gridap.FESpaces.UnconstrainedFESpace{Vector{Float64}, Gridap.FESpaces.NodeToDofGlue{VectorValue{2, Int32}}})
   @ Gridap.FESpaces C:\Users\marya\.julia\packages\Gridap\971dU\src\FESpaces\Assemblers.jl:296
 [3] assemble_vector(f::Function, V::Gridap.FESpaces.UnconstrainedFESpace{Vector{Float64}, Gridap.FESpaces.NodeToDofGlue{VectorValue{2, Int32}}})
   @ Gridap.FESpaces C:\Users\marya\.julia\packages\Gridap\971dU\src\FESpaces\Assemblers.jl:352
 [4] top-level scope
   @ In[95]:7

```

or any other ways to define load on load line?  
thank you!

---

<div class="post-metadata">

**Author:** ![Sukera](https://avatars.discourse-cdn.com/v4/letter/s/ce7236/32.png) [@Sukera](https://discourse.julialang.org/u/Sukera)\
**Post date:** [June 20, 2023, 3:49am UTC](https://discourse.julialang.org/t/assemble-load-line-vector/100575/2 "2023-06-20T03:49:16Z")

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What is `fem_params.V0_Disp`? The error message suggests that there’s a Matrix instead of a Vector somewhere.

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<div class="post-metadata">

**Author:** ![mary](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mary/32/53139_2.png) [@mary](https://discourse.julialang.org/u/mary)\
**Post date:** [June 20, 2023, 3:51am UTC](https://discourse.julialang.org/t/assemble-load-line-vector/100575/3 "2023-06-20T03:51:45Z")

</div>

it is FE test space

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<div class="post-metadata">

**Author:** ![mary](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mary/32/53139_2.png) [@mary](https://discourse.julialang.org/u/mary)\
**Post date:** [June 20, 2023, 5:46pm UTC](https://discourse.julialang.org/t/assemble-load-line-vector/100575/4 "2023-06-20T17:46:44Z")

</div>

are there any suggestion for this issue?

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<div class="post-metadata">

**Author:** ![Sukera](https://avatars.discourse-cdn.com/v4/letter/s/ce7236/32.png) [@Sukera](https://discourse.julialang.org/u/Sukera)\
**Post date:** [June 20, 2023, 6:49pm UTC](https://discourse.julialang.org/t/assemble-load-line-vector/100575/5 "2023-06-20T18:49:27Z")

</div>

There isn’t really much we can suggest here; the error message communicates that it needs to be a collection of vectors, not matrices. My best guess is that the function you’re passing to `assemble_vector` returns a matrix instead of a vector.

I’m not familiar with Gridap, but there really isn’t enough information to give more specific help here, sorry 🤷

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<div class="post-metadata">

**Author:** ![mary](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mary/32/53139_2.png) [@mary](https://discourse.julialang.org/u/mary)\
**Post date:** [June 20, 2023, 6:53pm UTC](https://discourse.julialang.org/t/assemble-load-line-vector/100575/6 "2023-06-20T18:53:02Z")

</div>

thank you for your response