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Re: rounding errors [message #24917 is a reply to message #24915]

Fri, 27 April 2001 07:21

Liam E. Gumley
Messages: 378
Registered: January 2000

Senior Member

Randall Skelton wrote:
> For the record, I had no idea that IDL requires you to explicitly state
> 'a=2.348339d0' instead of a=double(2.348339).

This is a subtle but important point. DOUBLE() is a type conversion
function, and

a = double(2.348339)

shows a FLOAT argument being converted to a DOUBLE. The safest way to
'cast' a double variable is

a = 2.348339d

or use an array creation function such as DBLARR, DINDGEN, REPLICATE, or
MAKE_ARRAY, e.g.,

b = dblarr(10)
c = dindgen(10)
d = replicate(1.0d, 10)
e = make_array(10, /double)

Cheers,
Liam.
http://cimss.ssec.wisc.edu/~gumley

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[Message index]

		Re: rounding errors By: thompson on Fri, 27 April 2001 11:34
		Re: rounding errors By: Liam E. Gumley on Fri, 27 April 2001 10:01
		Re: rounding errors By: Karl Schultz on Fri, 27 April 2001 09:07
		Re: rounding errors By: Paul van Delst on Fri, 27 April 2001 08:47
		Re: rounding errors By: Craig Markwardt on Fri, 27 April 2001 08:52
		Re: rounding errors By: John-David T. Smith on Fri, 27 April 2001 08:39
		Re: rounding errors By: thompson on Fri, 27 April 2001 08:23
		Re: rounding errors By: Dominic R. Scales on Fri, 27 April 2001 07:41
		Re: rounding errors By: Randall Skelton on Fri, 27 April 2001 07:51
		Re: rounding errors By: Liam E. Gumley on Fri, 27 April 2001 07:21
		Re: rounding errors By: Craig Markwardt on Fri, 27 April 2001 06:44
		Re: rounding errors By: Randall Skelton on Fri, 27 April 2001 06:17
		Re: rounding errors By: Dominic R. Scales on Fri, 27 April 2001 04:38
		Re: rounding errors By: Alex Schuster on Fri, 27 April 2001 03:52
		Re: rounding errors By: James Kuyper on Wed, 02 May 2001 08:06
		Re: rounding errors By: James Kuyper on Wed, 02 May 2001 08:07

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