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Re: Help needed!! [message #70503 is a reply to message #70502]

Fri, 16 April 2010 10:48

R.G.Stockwell
Messages: 163
Registered: October 2004

Senior Member

"bala murugan" <bala2305@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.

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[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

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