Re: [Bug-apl] Boolean Packing

[Blake McBride]

Big trade-off.  Packing and unpacking with a lot of operations has got to be CPU expensive.  Not packing is memory expensive.  If I am correct, then I have a slight leaning towards the way GNU APL did it.  If I am wrong and the expense of packing / unpacking over many operations is not expensive, then I'd lean towards IBM.

Blake

On Thu, Aug 20, 2015 at 3:16 PM, Mike Duvos <address@hidden> wrote:

[IBM APL2]

      WA←⎕WA ⋄ A←1000 1000⍴1=1 ⋄ WA-⎕WA
125056
      

[GNU APL]

      WA←⎕WA ⋄ A←1000 1000⍴1=1 ⋄ WA-⎕WA
48046080

APL2 obviously packs boolean ravels 8 bits per byte.  How does GNU APL store its booleans?

I use large bitmaps a lot in my code, so having them stored packed in the workspace is a huge issue for me.