# Delete! in sparse matrix
**URL:** https://discourse.julialang.org/t/delete-in-sparse-matrix/2634
**Category:** General Usage
**Created:** [March 13, 2017, 8:53am UTC](https://discourse.julialang.org/t/delete-in-sparse-matrix/2634 "2017-03-13T08:53:08Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@CarloLucibello](https://discourse.julialang.org/u/CarloLucibello)
#### Post date: [March 13, 2017, 8:53am UTC](https://discourse.julialang.org/t/delete-in-sparse-matrix/2634/1 "2017-03-13T08:53:08Z")
suppose you have the following sparse matrix
```julia
julia> type A end
julia> m=spzeros(A,10,10)
10×10 SparseMatrixCSC{A,Int64} with 0 stored entries
julia> m[1,1] = A()
A()
```
Now I would like to remove the element in (1,1).
If `m` was a dictionary I would use `delete!(m, (1,1))`. Is there a similar method for sparse matrices?
Cheers,
Carlo
---
### Author:  [@mauro3](https://discourse.julialang.org/u/mauro3)
#### Post date: [March 13, 2017, 8:59am UTC](https://discourse.julialang.org/t/delete-in-sparse-matrix/2634/2 "2017-03-13T08:59:49Z")
You need to define what “zero” means for your type, consider:
```julia
julia> m[1,2]
------ MethodError --------------------- Stacktrace (most recent call last)
[1] — getindex(::SparseMatrixCSC{A,Int64}, ::Int64, ::Int64) at sparsematrix.jl:2092
MethodError: no method matching zero(::Type{A})
Closest candidates are:
zero(::Type{Base.LibGit2.Oid}) at libgit2/oid.jl:88
zero(::Type{Base.Pkg.Resolve.VersionWeights.VWPreBuildItem}) at pkg/resolve/versionweight.jl:80
zero(::Type{Base.Pkg.Resolve.VersionWeights.VWPreBuild}) at pkg/resolve/versionweight.jl:120
...
```
Once you’ve done that, set `m[1,1]=your_zero`. If you want to free the memory used now storing a “zero” at `m[1,1]` use `dropzero!`.
---
### Author:  [@CarloLucibello](https://discourse.julialang.org/u/CarloLucibello)
#### Post date: [March 13, 2017, 9:52am UTC](https://discourse.julialang.org/t/delete-in-sparse-matrix/2634/3 "2017-03-13T09:52:31Z")
nice, thanks!