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Re: [Q]: ID analog to FORTRAN "sign" function [message #21929]

Mon, 09 October 2000 00:00

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

Alex Schuster <alex@pet.mpin-koeln.mpg.de> writes:
>> Results:
>> =========
>> The result type is the same as a.
>> The value of the result is
>> | a | if b >= zero
>> and -| a | if b < zero.
>
> No, but you can easily write it:
>
> function sign, a, b
> if ( b ge 0 ) then $
> return, abs( a ) $
> else $
> return, -abs( a )
> end

And, after the vector elf is done with it:

function sign, a, b
s = 2*(b GE 0) - 1 ;; +1 or -1
return, s*abs(a)
end

This function works with B as a scalar or a vector. If it's a vector
then it must have the same dimensions as A.

Craig

P.S. Recovering from pneumonia, Ugh.
--
------------------------------------------------------------ --------------
Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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		Re: [Q]: ID analog to FORTRAN "sign" function By: Craig Markwardt on Mon, 09 October 2000 00:00
		Re: [Q]: ID analog to FORTRAN "sign" function By: Alex Schuster on Mon, 09 October 2000 00:00

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