html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/issues/2074#issuecomment-383723159,https://api.github.com/repos/pydata/xarray/issues/2074,383723159,MDEyOklzc3VlQ29tbWVudDM4MzcyMzE1OQ==,3019665,2018-04-23T21:06:42Z,2018-04-23T21:06:42Z,NONE,"> from what I understand `da.dot` implements... a limited special case of `da.einsum`?

Basically `dot` is an inner product. Certainly inner products can be formulated using Einstein notation (i.e. calling with `einsum`).

The question is whether the performance keeps up with that formulation. Currently it sounds like chunking causes some problems right now IIUC. However things like `dot` and `tensordot` dispatch through optimized BLAS routines. In theory `einsum` should do the same ( https://github.com/numpy/numpy/pull/9425 ), but the experimental data still shows a few warts. For example, `matmul` is implemented with `einsum`, but is slower than `dot`. ( https://github.com/numpy/numpy/issues/7569 ) ( https://github.com/numpy/numpy/issues/8957 ) Pure `einsum` implementations seem to perform similarly.

> I ran a few more benchmarks...

What are the arrays used as input for this case?

> ...apparently `xarray.dot` on a dask backend is situationally faster than all other implementations when you are not reducing on any dimensions...

Having a little trouble following this. `dot` reduces one dimension from each input. Excepting if one of the inputs is 0-D (i.e. a scalar), then it is just multiplying a single scalar through an array. Is that what you are referring?","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,316618290
https://github.com/pydata/xarray/issues/2074#issuecomment-383637379,https://api.github.com/repos/pydata/xarray/issues/2074,383637379,MDEyOklzc3VlQ29tbWVudDM4MzYzNzM3OQ==,3019665,2018-04-23T16:26:51Z,2018-04-23T16:26:51Z,NONE,"Might be worth revisiting how `da.dot` is implemented as well. That would be the least amount of rewriting for you and would generally be nice for Dask users. If you have not already, @crusaderky, it would be nice to raise an issue over at Dask with a straight Dask benchmark comparing Dask Array's `dot` and `einsum`.

cc @mrocklin","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,316618290