# View + LinearAlgebra.BLAS.gemm!
**URL:** https://discourse.julialang.org/t/view-linearalgebra-blas-gemm/55720
**Category:** New to Julia
**Created:** [February 21, 2021, 2:26pm UTC](https://discourse.julialang.org/t/view-linearalgebra-blas-gemm/55720 "2021-02-21T14:26:54Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@PharmCat](https://discourse.julialang.org/u/PharmCat)
#### Post date: [February 21, 2021, 2:26pm UTC](https://discourse.julialang.org/t/view-linearalgebra-blas-gemm/55720/1 "2021-02-21T14:26:54Z")
try to use:
```julia
LinearAlgebra.BLAS.gemm!('T', 'N', one(T), view(mx, block, :), A, one(T), B)
```
where `block` - Vector{Int}
and have:
ERROR: ArgumentError: strides is invalid for SubArrays with indices of type Vector{Int64}
can I use views with LinearAlgebra.BLAS.gemm!?
---
### Author:  [@joaquimg](https://discourse.julialang.org/u/joaquimg)
#### Post date: [February 21, 2021, 5:25pm UTC](https://discourse.julialang.org/t/view-linearalgebra-blas-gemm/55720/2 "2021-02-21T17:25:54Z")
Consider using the 5 argument `mul!` also from `LinearAlgebra`
---
### Author:  [@stevengj](https://discourse.julialang.org/u/stevengj)
#### Post date: [February 21, 2021, 8:14pm UTC](https://discourse.julialang.org/t/view-linearalgebra-blas-gemm/55720/3 "2021-02-21T20:14:38Z")
> [@PharmCat](#):
>
> can I use views with LinearAlgebra.BLAS.gemm!?
The underlying BLAS API doesn’t support views with an arbitrary vector of indices.
(You can use `mul!`, but realize that you will pay a performance price compared to BLAS multiplies because it is falling back to the generic multiplication routine.)
---
### Author:  [@PharmCat](https://discourse.julialang.org/u/PharmCat)
#### Post date: [February 21, 2021, 8:37pm UTC](https://discourse.julialang.org/t/view-linearalgebra-blas-gemm/55720/4 "2021-02-21T20:37:13Z")
Thank you! `mul!` works fine, but I didn’t make a deep benchmark 😸