Problem with A_mul_B! and plan_idct, possible bug?



Hi all!
I’m running Julia 0.5 on Linux, and I found this weird thing, which I think could be a bug:

x = randn(10);     # input value             
x2 = copy(x);      # copy of input value
y = zeros(10);     # output
A = plan_idct(x);  # plan an inverse discrete cosine transform
A_mul_B!(y,A,x);   # apply transform in place in y (1)
norm(x-x2)         # here x should not be modified 
>2.7...            # but it's not!!

In line (1) if change plan_idct with plan_dct, plan_fft or plan_ifft (in the latter 2 cases you need complex vector)
this issue does not happen.
The problem is solved when using y .= A*x. But my feeling is that something is wrong with A_mul_B!
Please let me know if you experience the same issue or if this was already fixed in julia 0.6!
Thank you!


But perhaps it should be documented better than just this comment.


thanks for the answer! yes I agree that maybe it should appear in the docs!