issue_comments: 1115117344

Nice this looks like an improvement for everything other than dask arrays with only 100 elements, which is not a good use-case for dask.

I was slightly concerned that the recrusive algorithm wouldn't work well with dask but it does seem to work better.

``` python def other_polyval(coord, coeffs, degree_dim="degree"): x = coord.data

deg_coord = coeffs[degree_dim]
N = int(deg_coord.max()) + 1

lhs = xr.DataArray(
    np.stack([x ** (N - 1 - i) for i in range(N)], axis=1),
    dims=(coord.name, degree_dim),
    coords={
        coord.name: coord.data,
        degree_dim: np.arange(deg_coord.max() + 1)[::-1],
    },
)
return xr.dot(lhs, coeffs, dims=degree_dim)

coeffs = xr.DataArray(np.random.randn(2), dims="degree") da = xr.DataArray(dask.array.random.random((10**6), chunks=(10000)), dims=("x")) print(len(da.data.dask)) print(len(xr.polyval(da, coeffs).data.dask)) print(len(other_polyval(da, coeffs).data.dask)) 100 502 1005 ```