INF and NAN values

• Example

SP4CEBAR 2023-05-12 17:28 (Edited)

These values are some extra tools to your NX toolbox.

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Definitions

• INF = 0^(-1)
• NAN = -(-1)^0.5
• NAN = -(INF-INF)
• -INF = -INF
• -NAN = -NAN

Properties

When "INF" and "NAN" are used below, it is a variable holding the value INF or NAN respectively.

• These values can be assigned to variables
• most calculations with NAN or INF become NAN or INF

INF

• print INF = INF returns -1 which is true
  • the same is true for negative INF
  • this makes inf easily detectable like IF V=INF THEN PRINT "V IS INF"

NAN

• print NAN = NAN returns 0 which is false, the same is true for negative NAN
• NAN can be detected using: if not v=v then print "v is nan"
• if NAN then print "true" else print "false" prints true
• any comparison with NAN or -NAN returns 0
  • except nan<>nan, -nan<>nan, nan<>-nan, -nan<>-nan, which always return -1
• any calculation with NAN or -NAN returns NAN or -NAN
  • expressions that return nan
    • print nan+nan, nan-nan, nan*nan, -1*nan
  • expressions that return -nan
    • print -nan+-nan, -nan+nan, -nan*-nan, -nan*nan

Future Research

• "UNDEFINED" and "NIL" may also be possible to get somehow
• can you differentiate between nan and -nan, as they appear to have identical properties

SP4CEBAR 2023-05-12 18:51

INF is very useful if you need the biggest number available

SP4CEBAR 2026-09-06 15:28 (Edited)

here's a NAN-detector:
if not v=v then print "v is nan"

SP4CEBAR 2026-09-06 16:17

experiments to try to differentiate between nan and -nan (no success, they appear to have identical properties)

NAN = -(-1)^0.5
INF = 0^(-1)

print nan+nan, nan-nan, nan*nan, -1*nan
print -nan+-nan, -nan+nan, -nan*-nan, -nan*nan
print abs(-nan), abs(nan),
if NAN then print "true", else print "false",
if -NAN then print "true" else print "false"
print nan/-nan, nan/nan, -nan/nan, -nan/-nan

print nan=0, nan<0, nan>0,"  ",
print nan<inf, nan>inf, nan=inf
print -nan<inf, -nan>inf, -nan=inf,"  ",
print nan>nan, nan<nan, nan=nan

print nan<>nan, -nan<>nan, nan<>-nan, -nan<>-nan

print nan<-nan, nan>-nan, nan=-nan,"  ",
print sgn(nan), sgn(-nan)
poke $a000, nan
poke $a001, -nan
pokew $a010, nan
pokew $a020, -nan
pokel $a030, nan
pokel $a040, -nan
print peek($a000), peekw($a010), peekl($a030)
print peek($a001), peekw($a020), peekl($a040)
print peek($a010), peek($a011), peek($a012), peek($a013),"  ",
print peek($a020), peek($a021), peek($a022), peek($a023)
print peek($a030), peek($a031), peek($a032), peek($a033)
print peek($a040), peek($a041), peek($a042), peek($a043)