comp.lang.idl-pvwave archive: archive » Negative array indices

Home » Public Forums » archive » Negative array indices

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: Negative array indices [message #73902 is a reply to message #73811]

Thu, 02 December 2010 17:40

penteado
Messages: 866
Registered: February 2018

Senior Member
Administrator

On Dec 2, 7:54 pm, b_gom <b_...@hotmail.com> wrote:
> I guess this leads to this behaviour:
> IDL> x=findgen(10)
> IDL> print,x[-4:0]
> % Illegal subscript range: X.
>
> because this gets translated to:
> IDL> print,x[6,0]
> which isn't allowed.

Not allowed just because you are trying to decrease the index with a
positive stride (it will never get to 0 starting from 5 and adding
increments of 1). This does work:

IDL> x=findgen(10)
IDL> print,x[-4:0:-1]
6.00000 5.00000 4.00000 3.00000 2.00000
1.00000 0.00000
IDL> print,x[6:0:-1]
6.00000 5.00000 4.00000 3.00000 2.00000
1.00000 0.00000

Report message to a moderator

[Message index]

		Negative array indices By: b_gom on Thu, 02 December 2010 13:54
		Re: Negative array indices By: penteado on Thu, 02 December 2010 17:40
		Re: Negative array indices By: penteado on Thu, 02 December 2010 17:28
		Re: Negative array indices By: b_gom on Thu, 02 December 2010 16:35
		Re: Negative array indices By: David Fanning on Thu, 02 December 2010 14:50

Previous Topic:	New Graphics Challange
Next Topic:	Convolution Kernel

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Tue Dec 02 05:17:49 PST 2025

Total time taken to generate the page: 1.44493 seconds