====== Rounding======

===== Introduction =====

ACSUtils provides a full set of functions to round fixed-point numbers to integers.

<note warning>Current GZDoom provides built-in functions [[zdoom>Floor_(ACS_function)|floor]], [[zdoom>ceil]] and [[zdoom>round]], but these functions aren't available in Zandronum 3.0 and **silently return 0** there, because all unimplemented built-in ACS functions return 0.

Before using ACSUtils, rename either the built-in functions (by editing ''zspecial.acs'') or the ACSUtils functions (by editing ''acsutils.acs'') to something else. Otherwise, ACSUtils won't compile.
</note>

===== Rounding modes =====

There are four rounding modes:

  * ''trunc'' -- zeroes the fractional part of the number
  * ''floor'' -- rounds the number down
  * ''ceil'' -- round the number up
  * ''round'' -- rounds the number to the closest integer

A table that demonstrates the differences between rounding modes:

^  x   ^ round(x) ^ floor(x) ^ ceil(x) ^ trunc(x) ^
^   1.3|         1|         1|        2|         1|
^   1.5|    1 or 2|         1|        2|         1|
^   1.8|         2|         1|        2|         1|
^  -1.3|        -1|        -2|       -1|        -1|
^  -1.5|  -2 or -1|        -2|       -1|        -1|
^  -1.8|        -2|        -2|       -1|        -1|

===== Functions =====

Every rounding mode is available as two functions:
  * Functions without the ''i'' prefix return a fixed, e.g. ''floor(2.3) == 2.0''.
  * Functions with the ''i'' prefix return an int, e.g. ''ifloor(2.3) == 2''.

^ Mode  ^ fixed result ^ int result ^
^ floor | ''fixed floor(fixed x)'' | ''int ifloor(fixed x)'' |
^ ceil  | ''fixed ceil(fixed x)''  | ''int iceil(fixed x)''  |
^ round | ''fixed round(fixed x)'' | ''int iround(fixed x)'' |
^ trunc | ''fixed trunc(fixed x)'' | ''int itrunc(fixed x)'' |