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

I’m not mathematically gifted, but shouldn’t 957%60 be 15 remainder 57?

Google and my desktop calculator certainly think so.

So where am I going wrong here? The following code

exten => 7,1,Verbose(Context: ${CONTEXT} Exten:${EXTEN})

same => n,Set(myNum

## 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