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Re: assignment inside boolean expression [message #20710 is a reply to message #20613]

Tue, 18 July 2000 00:00

Martin Schultz
Messages: 515
Registered: August 1997

Senior Member

Ben Tupper wrote:
>
> Craig Markwardt wrote:
>
>> Not to undercut you, but will (X AND 1) do the trick?
>>
>
> Thanks to Ken and Craig. I think for my purposes the following should suffice (I
> guess as long as I make sure that I'm working with an integer/long/byte type.)
>
> X = Indgen(6) - 2
>
> For i = 0, N_elements(X)-1 Do $
> If X then Print, X[i], ': Odd' Else print, X[i], ': Even'
>
> -2: Even
> -1: Odd
> 0: Even
> 1: Odd
> 2: Even
> 3: Odd
>
> Thanks again,
>
> Ben

but if you start increasing the number of elements of X to say 1000000,
you are
certainly better off with:
answer=['even','odd']
print,answer[ (x and 1) ]

no loop ;-)

Example:
IDL> x=lindgen(20)-5
IDL> answer=['even','odd']
IDL> print,answer[x and 1]
odd even odd even odd even odd even odd even odd even odd even odd even
odd even odd even

BTW: X MOD 2 does not work for negative numbers !!!
IDL> print,answer[x mod 2]
even even even even even even odd even odd even odd even odd even odd
even odd even odd even

Cheers,
Martin
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[Message index]

		assignment inside boolean expression By: Patrick Broos on Mon, 10 July 2000 00:00
		Re: assignment inside boolean expression By: Martin Schultz on Tue, 18 July 2000 00:00
		Re: assignment inside boolean expression By: Martin Schultz on Tue, 18 July 2000 00:00

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