Re: [Ql-Users] Bevaiour of DIV with negative numbers in SBASIC (QPC2)

[George Gwilt]

> On 5 Jan 2017, at 15:27, Martyn Hill  wrote:
> 
> Hi everyone
> 
> Can anyone tell me the expected behaviour for the integer-divide operator 
> 'DIV' in SBASIC, when provided with a negative dividend/numerator?
> 
> My number-theory is a bit rusty, but I would have thought that, say, -1 DIV 
> 10 should result in 0 (with remainder/MOD of -1).
> 
> Instead, on QPC2/SBASIC, I get the result -1 for that example - and (almost) 
> always 1 less than expected for negative dividends, thus:
> 
> 12 DIV 10 = 1
> 11 DIV 10 = 1
> 10 DIV 10 = 1
>   9 DIV 10 = 0
> ...
>   2 DIV 10 = 0
>   1 DIV 10 = 0
>   0 DIV 10 = 0
> * -1 DIV 10 = -1 - expected '0'**
> ** -2 DIV 10 = -1**
> **...**
> **  -9 DIV 10 = -1*
> *-10 DIV 10 = -1 - as expected*
> *-11 DIV 10 = -2 - expected '-1'
> -12 DIV 10 = -2
> 
> *etc...
> 
> Thanks in advance!
> 
> Martyn.

n DIV m = INT(n/m)

INT(a) gives the “integer part”  of a. There are three possibilities.

1. a is rounded up
2. a is rounded down
3. a is rounded to nearest

In S*BASIC a is rounded down. Thus -11 DIV 10 = INT(-11/10) = -2

George



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[Ql-Users] Bevaiour of DIV with negative numbers in SBASIC (QPC2)

[Martyn Hill]

Hi everyone

Can anyone tell me the expected behaviour for the integer-divide 
operator 'DIV' in SBASIC, when provided with a negative dividend/numerator?


My number-theory is a bit rusty, but I would have thought that, say, -1 
DIV 10 should result in 0 (with remainder/MOD of -1).


Instead, on QPC2/SBASIC, I get the result -1 for that example - and 
(almost) always 1 less than expected for negative dividends, thus:


 12 DIV 10 = 1
 11 DIV 10 = 1
 10 DIV 10 = 1
   9 DIV 10 = 0
...
   2 DIV 10 = 0
   1 DIV 10 = 0
   0 DIV 10 = 0
* -1 DIV 10 = -1 - expected '0'**
** -2 DIV 10 = -1**
**...**
**  -9 DIV 10 = -1*
*-10 DIV 10 = -1 - as expected*
*-11 DIV 10 = -2 - expected '-1'
-12 DIV 10 = -2

*etc...

Thanks in advance!

Martyn.
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