Discrete sinusoid transformation

[roxyboy]

Currently, the xrft package only has discrete Fourier transformation but what do people think about adding the option to take the discrete sinusoid transformation? If people are on board, I can work on this.

[rabernat]

I don't think that dask implements DST:
http://dask.pydata.org/en/latest/array-api.html#fast-fourier-transforms

So if you wanted to do this, you would probably have to implement it at the dask level. You could start by raising an issue in dask:
https://github.com/dask/dask/issues

[roxyboy]

Ok, linking the issue I opened on dask: dask/dask#3250

[roxyboy]

Linking issue #156 .