comp.lang.idl-pvwave archive: archive

Home » Public Forums » archive » Re: Help needed!!

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: Help needed!! [message #70497 is a reply to message #70496]

Fri, 16 April 2010 12:19

bala murugan
Messages: 23
Registered: April 2010

Junior Member

On Apr 16, 1:13 pm, Gray <grayliketheco...@gmail.com> wrote:
> On Apr 16, 2:06 pm, bala murugan <bala2...@gmail.com> wrote:
>
>
>
>
>
>> On Apr 16, 11:48 am, "R.G. Stockwell" <noem...@please.com> wrote:
>
>>> "bala murugan" <bala2...@gmail.com> wrote in message
>
>>> news:29ee4ec6-4803-44fd-aa5c-00fc0d2c9376@u21g2000yqc.google groups.com...
>
>>>> Hi people,
>
>>>> I am new to IDL. This is my first program in IDL. Can somebody point
>>>> out the errors in my code. I have been struggling to get it right.
>
>>>> CODE:
>
>>>> FUNCTION poissondist,fLambda,N
>>>> r = RANDOMU(SEED,1)
>>>> FOR j=1,N,1 DO BEGIN
>
>>> arrays are indexed from 0... N-1
>
>>>> x=poisson(j,fLambda)
>>>> if (x EQ r) THEN a[i]=j
>
>>> floating point numbers may never be exactly equal.
>>> Use a "if abs(x-r) lt 0.0001 then" type of statement
>
>>> as others have pointed out, 'a' and 'i' do not exist here.
>>> i have no idea what you think "i" should be.
>>> For a you will need to allocate an array inside that function, like so:
>>> FUNCTION poissondist,fLambda,N
>>> a = fltarr(N)
>>> r = RANDOMU(SEED,1)
>>> FOR j=0,N-1 DO BEGIN
>>> .... etc....
>
>>>> ENDFOR
>>>> RETURN,a
>>>> END
>
>>>> In the above code, the function "poisson" was written by me. It is as
>>>> follows,
>
>>>> CODE:
>
>>>> FUNCTION poisson,a,b
>>>> x = (b^a)/(exp(b)*factorial(a))
>>>> RETURN,x
>>>> END
>
>>> in the future, you may want to make sure a and b are passed in
>>> before executing that statement. for example:
>
>>> if n_elements(a) eq 0 then message,'missing a'
>>> if n_elements(b) eq 0 then message,'missing b'
>
>>> cheers,
>>> bob
>
>>> PS bonus info.
>
>>> Make sure that the code for
>>> FUNCTION poissondist,fLambda,N
>>> is in a file called poissondist.pro, and that it is in your IDL path.
>
>>> Also, make sure your function:
>>> FUNCTION poisson,a,b
>>> is in a file called poisson.pro, and that it is in your IDL path.
>
>> Guys, thanks a lot for the info.
>
>> Sorry, I made a mistake while copying the code and pasting it:
>
>> CODE:
>
>> FUNCTION poissondist,fLambda,N
>> FOR i=1,N,1 DO BEGIN
>> a = FLTARR(N)
>> r = RANDOMU(SEED,1)
>> FOR j=1,N,1 DO BEGIN
>> x=poisson(j,fLambda)
>> if abs(x-r) lt 0.0001 THEN a[i]=j
>> ENDFOR
>> ENDFOR
>> RETURN,a
>> END
>
>> I also came across another method. But am not sure if it does the same
>> thing as mentioned in the summary that I made.
>
>> The thing that I came across is as follows,
>
>> FUNCTION poissondist, fLambda, N
>> data = RANDOMU(SEED,N,POISSON=fLambda)
>> RETURN,data
>> END
>
>> Can you please clarify if the second method does the same thing as the
>> first?
>
>> Thanks,
>> B
>
> The second method does what you're looking for, the first may or may
> not but is overly complicated.

Thanks Gray....

But I would be glad if I can make the first method work....

If you have any suggestions of doing the first method in a different
way, please let me know...

By the way, thanks a lot!!!

Report message to a moderator

[Message index]

		Re: Help needed!! By: R.G.Stockwell on Sat, 17 April 2010 10:07
		Re: Help needed!! By: R.G.Stockwell on Sat, 17 April 2010 10:04
		Re: Help needed!! By: jeanh on Sat, 17 April 2010 07:57
		Re: Help needed!! By: Craig Markwardt on Fri, 16 April 2010 20:59
		Re: Help needed!! By: bala murugan on Fri, 16 April 2010 12:46
		Re: Help needed!! By: bala murugan on Fri, 16 April 2010 12:19
		Re: Help needed!! By: Gray on Fri, 16 April 2010 12:13
		Re: Help needed!! By: bala murugan on Fri, 16 April 2010 12:11
		Re: Help needed!! By: R.G.Stockwell on Fri, 16 April 2010 11:59
		Re: Help needed!! By: bala murugan on Fri, 16 April 2010 11:06
		Re: Help needed!! By: Gray on Fri, 16 April 2010 10:53
		Re: Help needed!! By: R.G.Stockwell on Fri, 16 April 2010 10:48
		Re: Help needed!! By: Gray on Fri, 16 April 2010 10:47
		Re: Help needed!! By: bala murugan on Fri, 16 April 2010 09:40
		Re: Help needed!! By: bala murugan on Fri, 16 April 2010 09:39
		Re: Help needed!! By: penteado on Fri, 16 April 2010 09:33
		Re: Help needed!! By: Craig Markwardt on Fri, 16 April 2010 09:23
		Re: Help needed!! By: bala murugan on Fri, 16 April 2010 09:18
		Re: Help needed!! By: penteado on Fri, 16 April 2010 09:10
		Re: Help needed!! By: bala murugan on Mon, 19 April 2010 10:16

Previous Topic:	Re: GridData Conundrum
Next Topic:	Comparison operators and floating-point errors

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Wed Oct 08 20:10:52 PDT 2025

Total time taken to generate the page: 0.00364 seconds