3 thoughts on - Problem With REMAINDER? 957%60 Be 15 Remainder 57 Not 15 Remainder -3 ?

• All I can tell you is where -3 comes from. From http://www.voip-info.org/wiki/view/Asterisk+Expressions :
  REMAINDER(x,y) computes the remainder of dividing x by y. The return value is x – n*y, where n is the value x/y, rounded to the nearest integer. If this quotient is 1/2, it is rounded to the nearest even number.

  -3 comes from:
  n = x/y = 957/60 = 15.95 which rounds to 16
  n*y = 16*60 = 960
  x – 960 = 957-960 = -3

  I’m not mathematically gifted either but I think the n is the problem. it shouldn’t be the rounded result it should be the integer part of x/y (n)

  Can you just use modulo instead: ${MATH(${myNum}%60,int)}

• Yes! That’s the one. Thank you. That’s a good workaround.

  The following test dialplan shows the bug (feature?)

  exten => 7,1,Verbose(Context: ${CONTEXT} Exten:${EXTEN})
  same => n,Set(secondsW)
  same => n,While($[${seconds} <= 400]); same => n,Set(minutes=$[FLOOR(${seconds} / 60)])
  same => n,Set(myRemainderSec=$[REMAINDER(${seconds},60)])
  same => n,SET(myModSec=${MATH(${seconds}%60,int)})
  same => n,Verbose(1,Seconds:${seconds} = Minutes:${minutes}
  Remainder Seconds:${myRemainderSec} modulo seconds:${myModSec})
  same => n,Set(seconds=$[${seconds}+3])
  same => n,EndWhile()

  This is the output:

  Seconds:57 = Minutes:0 Remainder Seconds:-3 modulo seconds:57
  Seconds:60 = Minutes:1 Remainder Seconds:0 modulo seconds:0
  Seconds:63 = Minutes:1 Remainder Seconds:3 modulo seconds:3
  Seconds:66 = Minutes:1 Remainder Seconds:6 modulo seconds:6
  Seconds:69 = Minutes:1 Remainder Seconds:9 modulo seconds:9
  Seconds:72 = Minutes:1 Remainder Seconds:12 modulo seconds:12
  Seconds:75 = Minutes:1 Remainder Seconds:15 modulo seconds:15
  Seconds:78 = Minutes:1 Remainder Seconds:18 modulo seconds:18
  Seconds:81 = Minutes:1 Remainder Seconds:21 modulo seconds:21
  Seconds:84 = Minutes:1 Remainder Seconds:24 modulo seconds:24
  Seconds:87 = Minutes:1 Remainder Seconds:27 modulo seconds:27
  Seconds:90 = Minutes:1 Remainder Seconds:-30 modulo seconds:30
  Seconds:93 = Minutes:1 Remainder Seconds:-27 modulo seconds:33
  Seconds:96 = Minutes:1 Remainder Seconds:-24 modulo seconds:36
  Seconds:99 = Minutes:1 Remainder Seconds:-21 modulo seconds:39
  Seconds:102 = Minutes:1 Remainder Seconds:-18 modulo seconds:42
  Seconds:105 = Minutes:1 Remainder Seconds:-15 modulo seconds:45
  Seconds:108 = Minutes:1 Remainder Seconds:-12 modulo seconds:48
  Seconds:111 = Minutes:1 Remainder Seconds:-9 modulo seconds:51
  Seconds:114 = Minutes:1 Remainder Seconds:-6 modulo seconds:54
  Seconds:117 = Minutes:1 Remainder Seconds:-3 modulo seconds:57
  Seconds:120 = Minutes:2 Remainder Seconds:0 modulo seconds:0

  Issue filed at https://issues.asterisk.org/jira/browse/ASTERISK-26493

• I saw this on the bug list first and sent a reply, but for the archives I’ll copy it here, too.

  REMAINDER() calls libm’s remainder(3) or remainderl(3), infix % calls fmod(3) or fmodl(3).

  remainder(3) is defined to round the quotient to the nearest int (always using round-to-even, notsithstanding the rounding mode), fmod(3) is defined to trunc(3)ate the quotient.

  So the result of x%y will always be in the range [0,x] and the results of remainder(x,y) will be in the range (-y/2,y/2].

  -JimC