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Re: byteoder for float numbers conversion [message #8136 is a reply to message #8071]

Thu, 06 February 1997 00:00

Thomas A. McGlynn
Messages: 23
Registered: March 1996

Junior Member

Peter Suetterlin wrote:
>
> In article <5d8mo8$n98@elaine44.stanford.edu>,
> yafeng@leland.Stanford.EDU (Meili Zhong) writes:
>
>> I want to convert the float numbers from UNIX format(big-edian)
>> to PC format(small-edian). For example, I have a float array
>> data(420)
>
> byteorder, data, /lswap
>
> Or have a look at the /XDR Keyword for opening files.
>
> Peter
>
> Peter "Pit" Suetterlin

I've had lots of problems with the byteorder routine. It's
been broken on a number of versions of IDL on Dec hardware
and some PC versions.

If you actually know that you just want to invert data of
a given type you can do things like:

float x[100];
qinvers = float(rotate(byte(x,0,4,100),5),0,100)

to invert bytes. You can look at the IDL astronomy library
rotines host_to_ieee and ieee_to_host at

http://idlastro.gsfc.nasa.gov/ftp/pro/misc

to see if any machines/IDL versions you're interested in have
errors in their byteorder implementations. There do
seem to be some problems indicated for linux and Windows
versions of IDL. These routines try to take care of these little
gotcha's in a generic way.

Good luck,

Tom McGlynn
tam@silk.gsfc.nasa.gov

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[Message index]

		byteoder for float numbers conversion By: yafeng on Tue, 04 February 1997 00:00
		Re: byteoder for float numbers conversion By: Thomas A. McGlynn on Thu, 06 February 1997 00:00
		Re: byteoder for float numbers conversion By: Liam Gumley on Tue, 18 February 1997 00:00
		Re: byteoder for float numbers conversion By: pit on Tue, 18 February 1997 00:00
		Re: byteoder for float numbers conversion By: wmc on Tue, 18 February 1997 00:00

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