Qestion about round up

[bilekflo]

May be a silly question but why does

⌈⍬ or ⌈⍳0 (numeric empty vector) delivers
¯1.797693135E308 and not an numeric empty vector?

BR Florian

[petermsiegel]

For ⌈⍬, the result is ⍬.

Do you mean ⌈/⍬? The result is based on the definition of reduce / for null elements in the argument; reduce uses the identity element when the operand is the maximum function ⌈, here the biggest negative number defined (for the current ⎕FR), or a special value for , and ⍪, else a DOMAIN ERROR.

See page 162 of the Dyalog APL Language Reference Guide for the formal definition, which isn't easy to parse.

Cheers.

For amusement:

      ⌈/2 3 0⍴0
¯1.797693135E308 ¯1.797693135E308 ¯1.797693135E308
¯1.797693135E308 ¯1.797693135E308 ¯1.797693135E308

[bilekflo]

Thank you for explanation. I wasn't aware of this.

BR Florian