| random integers between 0 and 1,000,000 [message #45972] |
Sat, 22 October 2005 19:29  |
mxd1007
Messages: 3
Registered: October 2005
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Junior Member |
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Hello,
I'm trying to generate 30 random integer numbers between 0 and
1,000,000 but I keep getting negative values. This is my IDL
statements:
FOR i = 0, 29 DO BEGIN
weights[i] = ULONG(1000000 * RANDOMU( seed, 1 ))
ENDFOR
the result when I print out the array weights:
17925 28066 15706 -4558 7450 9892 5340 -1674 -29667
-15997
-27046 -27854 -24859 29529 -31310 -7807 21139 8014 -14189
-24471
-16476 -6624 -23456 3042 30319 -20737 10945 -19432 3206
-11725
I would think if you cast ULONG onto the calculation, you would get
postitive values.
thanks in advance.
-Mike
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| Re: random integers between 0 and 1,000,000 [message #46038 is a reply to message #45972] |
Tue, 25 October 2005 02:17  |
Norbert Hahn
Messages: 46
Registered: May 2003
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Member |
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"James Kuyper" <kuyper@wizard.net> wrote:
> Norbert Hahn wrote:
>> "James Kuyper" <kuyper@wizard.net> wrote:
>>
>>> takes a 32 bit unsigned long with a value somewhere in the range from 0
>>> to 1000000, and converts it into a 16 bit signed int, with a range from
>>> -32768 to 32767.
>>
>> I took a closer look on what might have gone on. I ran the following
>> program:
>>
>> z = randomu(seed,30)
>> a = long (z*1000000) & print, a
>> b = ulong (z*1000000) & print, b
>> i = fix(a)
>> print, a
>>
>> I found that a(1) was negative (-20848). So I printed
Sorry for the typo! The line should read
"I found that i(1) was negative (-20848). So I printed"
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The hex numbers given in my example were correct with leading zeroes
omitted.
Norbert
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