What does "comma bar" mean?

Question

Please pardon my ignorance. I'm translating some APL to another format, and can't find anywhere what the function/meaning of a "comma bar" is. Not sure if this will come through, but it looks like this "⍪", and is encoded by U+236A.

It appears to combine 2 matrices, but while I've found a few mentions of the symbol itself, Google has not yet been able to tell me what it does.

For extra gratitude, please point me to a source where I can find information about what all the other symbols do.

Thanks!

Answer 1

The dyadic form of comma-bar is called a first-axis catenate.

With matrices and other multi-dimensional arrays, catenate expects the dimension at which the join is made to be specified. (See [], 'axis'.) If no dimension is specified, the last dimension is assumed. ⍪ (comma-bar) behaves in exactly the same manner as , except that the default dimension is the first. Again, if an axis is specified ⍪ will use that axis.

This microapl site has a good reference of basic symbols as well.

Search that site and wikipedia and you should have enough to go on. See the comments below for an implementation specific monadic version.