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Correlate function (bug?) [message #11103]

Fri, 13 March 1998 00:00

Theo Brauers
Messages: 58
Registered: November 1997

Member

Hi

I was facing a problem with the correlate function
which is demonstrated by the following IDL procedure:

pro testc
x=[1.D-5, 1.D-6, 0.0]
y=[1.D-5, 1.1D-6, 0.0]
f=[1.D0, 1.D1, 1.D2, 1.D3, 1.D4, 1.D5, 1.D6]
for i=0,6 do begin
print, i, correlate(x,y, /double) $
, correlate(x,y*f[i], /double) $
, correlate(x*f[i],y, /double) $
, correlate(x*f[i],y*f[i], /double)
endfor
END

giving the following result:

0 1.#QNAN00 1.#QNAN00 1.#QNAN00 1.#QNAN00
1 1.#QNAN00 1.#QNAN00 1.#QNAN00 1.#QNAN00
2 1.#QNAN00 1.#QNAN00 1.#QNAN00 1.#QNAN00
3 1.#QNAN00 1.#QNAN00 1.#QNAN00 0.99995432
4 1.#QNAN00 1.#QNAN00 1.#QNAN00 0.99995432
5 1.#QNAN00 0.99995432 0.99995432 0.99995432
6 1.#QNAN00 0.99995432 0.99995432 0.99995432

In my opinion there is no reason for an underflow or whatever causes
correlate to return NAN.

Best Theo

----------------------------------------------
Dr. Theo Brauers
Institut fuer Atmosphaerische Chemie (ICG-3)
Forschungszentrum Juelich
52425 JUELICH, Germany
Tel. +49-2461-61-6646 Fax. +49-2461-61-5346

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[Message index]

		Correlate function (bug?) By: Theo Brauers on Fri, 13 March 1998 00:00
		Re: Correlate function (bug?) By: John Smith on Tue, 17 March 1998 00:00
		Re: Correlate function (bug?) By: thompson on Mon, 16 March 1998 00:00

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