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Absolute value of negative number is negative [message #92691]

Mon, 08 February 2016 11:00

wlandsman
Messages: 743
Registered: June 2000

Senior Member

I was surprised to find that taking the absolute value of a 16 bit integer vector was yielding negative numbers.
While this is non-intuitive, I think it is unavoidable. --Wayne

IDL> tab= -32768S ;IDL won't let us define -32768 as a short integer

tab= -32768
^
% Integer constant must be less than 32768.

IDL> tab = intarr(1) ;but we can assign a short integer to -32768
IDL> tab[0] = -32768
IDL> help,tab ;Still a short integer
TAB INT = Array[1]
IDL> print,tab[0] ;Still a value of -32768
-32768
IDL> print,abs(tab[0]) ;Absolute value is negative!
-32768

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[Message index]

		Absolute value of negative number is negative By: wlandsman on Mon, 08 February 2016 11:00
		Re: Absolute value of negative number is negative By: Dick Jackson on Tue, 09 February 2016 13:26

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