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Re: SIGN function: signof(num or array of num) [message #70137 is a reply to message #70136]

Tue, 16 March 2010 08:43

Ding
Messages: 20
Registered: March 2008

Junior Member

On Mar 16, 10:51 am, Ding <gardener_2...@hotmail.com> wrote:
> Dear IDL users,
>
> I cannot find the SIGN function in IDL procedures, but one in
> Solarsoft ssw/maths/ SIGN which occupy the name, but different
> purpose( sign(a)*b). so I wrote the SIGNOF() function which is to get
> the sign of a number or array,
>
> Hopefully I am not repeating someone' work! you are welcome to
> comments!
>
> ; return the sign of the input data in an array of the same size
> ; -1 for negative elements
> ; 1 for positive elements
> ; 0 for 0 and complex number
> ; only works for numerics

return the sign of the input data in an array of the same size
-1 for negative elements
1 for positive elements
0 for 0 and complex number
only works for numerics
>a=[[1,-2],[0,3]]
> print, signof(a)
1 -1
0 1
>
More notes:

although signof(0) cause algorithm error, since 0/0 is defined as 0,
signof(0)=0, signof(Inf)=0. it can be used in an expression
signof(numeric variable or array)*10.0/5. etc.

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[Message index]

		Re: SIGN function: signof(num or array of num) By: Foldy Lajos on Tue, 16 March 2010 09:41
		Re: SIGN function: signof(num or array of num) By: Carsten Lechte on Tue, 16 March 2010 09:36
		Re: SIGN function: signof(num or array of num) By: Carsten Lechte on Tue, 16 March 2010 09:25
		Re: SIGN function: signof(num or array of num) By: Ding on Tue, 16 March 2010 09:17
		Re: SIGN function: signof(num or array of num) By: Carsten Lechte on Tue, 16 March 2010 08:46
		Re: SIGN function: signof(num or array of num) By: Ding on Tue, 16 March 2010 08:43
		Re: SIGN function: signof(num or array of num) By: Carsten Lechte on Tue, 16 March 2010 08:35
		Re: SIGN function: signof(num or array of num) By: Ding on Tue, 16 March 2010 08:32
		Re: SIGN function: signof(num or array of num) By: H. Evans on Tue, 16 March 2010 07:30

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