| Strange Bug with numeric double constants [message #14711] |
Mon, 22 March 1999 00:00  |
Alex Schuster
Messages: 124
Registered: February 1997
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Senior Member |
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Hi!
I just experienced some weird IDL behaviour:
IDL> help, 1.0d+2.0d
help, 1.0d+2.0d
^
% Syntax error.
IDL> help, 1d+2d
help, 1d+2d
^
% Syntax error.
Strange, isn't it? There's no problem with byte constants:
IDL> help, 1b+2b
<Expression> BYTE = 3
An additional blank helps:
IDL> help, 1d +2d
<Expression> DOUBLE = 3.0000000
I didn't try IDL 5.2, but it happened with 4.0 and 5.1 on Unix and
Windows. I guess IDL expects an exponential notation like 1d0, and is
confused by the nonnumeric plus character.
Alex
--
Alex Schuster Wonko@weird.cologne.de PGP Key available
alex@pet.mpin-koeln.mpg.de
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| Re: Strange Bug with numeric double constants [message #14742 is a reply to message #14711] |
Thu, 25 March 1999 00:00  |
badastro
Messages: 7
Registered: August 1998
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Junior Member |
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In comp.lang.idl-pvwave Alex Schuster <alex@rosa.mpin-koeln.mpg.de> wrote:
> Hi!
> I just experienced some weird IDL behaviour:
> IDL> help, 1.0d+2.0d
> help, 1.0d+2.0d
> ^
> % Syntax error.
> IDL> help, 1d+2d
> help, 1d+2d
> ^
> % Syntax error.
> Strange, isn't it?
Nope. ;-) IDL expects that what follows the 'd' is the exponent,
like 100 being 1.d2 or 1.d+2. If you put a 'd' after the 2, it doesn't
recognize it as being part of the exponent, so it barfs. The same
things happens if you use an 'e' instead of 'd'. It doesn't happen
with byte numbers because the 'b' doesn't precede an exponent.
* * * * * The Bad Astronomer * * * *
Phil Plait badastro@badastronomy.com
The Bad Astronomy Web Page: http://www.badastronomy.com
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