Ger wrote:

> Mike Horvath wrote:
> 
>> How do I calculate a random integer between n and p, inclusively?
>> 
>> 
>> Thanks
> #declare RSeed = seed(1);
> 
#declare RandomNumber = int(n + rand(RSeed) * (p - n));

-- 

Ger

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On 1/31/2016 9:06 PM, Ger wrote:
> Mike Horvath wrote:
>
>> How do I calculate a random integer between n and p, inclusively?
>>
>>
>> Thanks
> #declare RSeed = seed(1);
>
> #declare RandomNumber = n + rand(RSeed) * (p - n);
>

That results in a float, not an integer.


Mike

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Am 01.02.2016 um 02:55 schrieb Mike Horvath:
> How do I calculate a random integer between n and p, inclusively?

floor( rand(R)*((p-n)+1) + 0.5 )

should do the trick

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Mike Horvath wrote:

> On 1/31/2016 9:06 PM, Ger wrote:
>> Mike Horvath wrote:
>>
>>> How do I calculate a random integer between n and p, inclusively?
>>>
>>>
>>> Thanks
>> #declare RSeed = seed(1);
>>
>> #declare RandomNumber = n + rand(RSeed) * (p - n);
>>
> 
> That results in a float, not an integer.
> 
> 
> Mike

I corrected it.
-- 

Ger

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Am 01.02.2016 um 03:10 schrieb clipka:
> Am 01.02.2016 um 02:55 schrieb Mike Horvath:
>> How do I calculate a random integer between n and p, inclusively?
> 
> floor( rand(R)*((p-n)+1) + 0.5 )
> 
> should do the trick

... provided you figure out that you need to add n ;)

Oops.

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Yes, there are two functions to convert a float to a close-by integer:

1. Floor
If the float is, let's say, "11.4676475" (could be a multiplication of a
"rand" random result), floor returns "11" (the next integer BELOW that
float).

2. Ceil(ing)
If the float is, let's say, "11.4676475" (could be a multiplication of a
"rand" random result), floor returns "12" (the next integer ABOVE that
float).

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On 1-2-2016 3:10, clipka wrote:
> Am 01.02.2016 um 02:55 schrieb Mike Horvath:
>> How do I calculate a random integer between n and p, inclusively?
>
> floor( rand(R)*((p-n)+1) + 0.5 )
>
> should do the trick
>

Why not this: int(RRand(n,p,R))

-- 
Thomas

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On 02/01/2016 03:06 AM, Thomas de Groot wrote:
> On 1-2-2016 3:10, clipka wrote:
>> Am 01.02.2016 um 02:55 schrieb Mike Horvath:
>>> How do I calculate a random integer between n and p, inclusively?
>>
>> floor( rand(R)*((p-n)+1) + 0.5 )
>>
>> should do the trick
>>
>
> Why not this: int(RRand(n,p,R))
>
RRand(Min,Max,RandSeededStream) from rand.inc. To get the inclusive part 
of the request I think we need:

int(RRand(n,p+(1-1e-6),R))

or

floor(RRand(n,p+(1-1e-6),R))

Bill P.

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On 1-2-2016 13:19, William F Pokorny wrote:
> On 02/01/2016 03:06 AM, Thomas de Groot wrote:
>> On 1-2-2016 3:10, clipka wrote:
>>> Am 01.02.2016 um 02:55 schrieb Mike Horvath:
>>>> How do I calculate a random integer between n and p, inclusively?
>>>
>>> floor( rand(R)*((p-n)+1) + 0.5 )
>>>
>>> should do the trick
>>>
>>
>> Why not this: int(RRand(n,p,R))
>>
> RRand(Min,Max,RandSeededStream) from rand.inc. To get the inclusive part
> of the request I think we need:
>
> int(RRand(n,p+(1-1e-6),R))
>
> or
>
> floor(RRand(n,p+(1-1e-6),R))
>
> Bill P.

Are the Min and Max not inclusive by default? I always got that impression.

-- 
Thomas

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On 02/01/2016 07:21 AM, Thomas de Groot wrote:
> On 1-2-2016 13:19, William F Pokorny wrote:
>> On 02/01/2016 03:06 AM, Thomas de Groot wrote:
>>> On 1-2-2016 3:10, clipka wrote:
>>>> Am 01.02.2016 um 02:55 schrieb Mike Horvath:
>>>>> How do I calculate a random integer between n and p, inclusively?
>>>>
>>>> floor( rand(R)*((p-n)+1) + 0.5 )
>>>>
>>>> should do the trick
>>>>
>>>
>>> Why not this: int(RRand(n,p,R))
>>>
>> RRand(Min,Max,RandSeededStream) from rand.inc. To get the inclusive part
>> of the request I think we need:
>>
>> int(RRand(n,p+(1-1e-6),R))
>>
>> or
>>
>> floor(RRand(n,p+(1-1e-6),R))
>>
>> Bill P.
>
> Are the Min and Max not inclusive by default? I always got that impression.
>
For floats yes.

Mike wants integers so we are using int() or floor(). Seems to me the 
only way we can get the Max integer value is if the rand() function 
returns exactly 1.0 - which it will pretty much never do, but might.

The +(1-1e-6) makes it so we get the Max integer value only one 
millionth less often than ideally we should.

We could specify a max integer 1 larger than we really want for p, but 
then rand() will be a troublemaker and give us that 1.0 value in our 
scene.

Bill P.

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