Re: [Bug-apl] Numerical error

[Juergen Sauermann]

Hi Brian,

thanks, fixed in SVN 644.

Please note that things like that can still happen - powers of negative numbers can give
complex numbers and rounding up or down of complex numbers is somewhat different
from rounding up or down of real numbers. In your example T←¯1⋆2 gave a complex number close
to 1 which was then multiplied and rounded as a complex number. For ⌊ and ⌈ small rounding errors
can give differences of 1, ¯1, 0J1, or 0J¯1 in the "expected" result.

/// Jürgen

On 07/07/2015 07:13 PM, McGuinness, Brian wrote:

The Toronto APL Toolkit function RNDE
generates unexpected complex numbers in
GNU APL 1.5.1.

For example:

T{<-}{neg}1*{ceiling}2|X
T{times}{floor}0.5+X{times}T

for X = 11.5 gives me 12J{neg}1 instead of 12.

--- Brian