2-node-supercomputer.net 2020-05-31

Julia’s Hermitian transpose operator

In Julia the so-called transpose operator does a little more than I expected:

julia> [1+im]'
[1-im]

That is, it is the Hermitian operator or conjugate-transpose, frequently abbreviated as a dagger, †.

That means that A' = conj(transpose(A)).

It took me awhile to figure that out. I had always assumed that ' is just the transpose, not taking the complex conjugate. Phew, finally found that.

Does it make sense? Yes, I think so. That is exactly what you will usually want. Perhaps it would have been nice to use the symbol †, for clarity.

Then again, this was a changed made sometime in the 0.x days of Julia, and it is only a matter of time until the new meaning is well-known and we are all used to it.