expand_op in wiki seems typo

[erickaoshoulin]

Appreciate the ANS tutorial! Thank you guys.

In wiki:
2: decode-step-constraint: During the expand_state we repeatedly perform the state expansion operation:

start -> x_0

expand_op -> x_i = x_{i-1} + bit

It should be

expand_op -> x_i = 2*x_{i-1} + bit

right?

[kedartatwawadi]

Yes that is right! Thanks for informing about the typo.
I fixed this in the wiki. Let us know in case you find other typos :).

Also, the rANS and tANS implementations are now merged to the main branch:

1. https://github.com/kedartatwawadi/stanford_compression_library/blob/main/compressors/rANS.py
2. https://github.com/kedartatwawadi/stanford_compression_library/blob/main/compressors/tANS.py

[erickaoshoulin]

Hello Kedar,
I think it's another typo In wiki tANS encode part:

Now, lets say, freq[s] <= 2^y < (2*freq[s] - 1). Then we know the following:

For any x_shrunk in [2^y, 22^y - 1], we need to output r+1-e bits.
For any x_shrunk in [2^{y-1}, 22^{y-1} - 1], we need to output r+2-e bits.

It should be y bits instead of e bits.

For any x_shrunk in [2^y, 22^y - 1], we need to output r+1-y bits.
For any x_shrunk in [2^{y-1}, 22^{y-1} - 1], we need to output r+2-y bits.

[kedartatwawadi]

Thanks again @erickaoshoulin, the typo is now fixed