| WRONG RESULTS WITH IDL [message #11714] |
Tue, 05 May 1998 00:00  |
loewenthal
Messages: 1
Registered: May 1998
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Junior Member |
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Hi Folks
For calculation of beam-propagation I use IDL. But now I realize that
for large arguments, even with double-precision, IDL gives wrong
results:
For example:
sin(12345678901.12345678901) = -03727 9004 9960 8007
where IDL get:
IDL> x = double(12345678901.12345678901)
IDL> print, sin(x)
0.098761418
Can somebody confirm this result, and does anybody know the solution
to overcome this problem?
Best regards
Frank
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| Re: WRONG RESULTS WITH IDL [message #11765 is a reply to message #11714] |
Thu, 14 May 1998 00:00  |
Anders Johannesson
Messages: 3
Registered: May 1998
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Junior Member |
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Frank Loewenthal wrote in message <354ef5cc.356842983@news>...
> Hi Folks
>
> For calculation of beam-propagation I use IDL. But now I realize that
> for large arguments, even with double-precision, IDL gives wrong
> results:
> For example:
>
> sin(12345678901.12345678901) = -03727 9004 9960 8007
>
> where IDL get:
>
> IDL> x = double(12345678901.12345678901)
> IDL> print, sin(x)
> 0.098761418
>
> Can somebody confirm this result, and does anybody know the solution
> to overcome this problem?
################################################
You are not using double. Try it this way: (Note the d for double)
print,sin(12345678901.12345678901d)
Anders Johannesson
#################################################
>
> Best regards
>
> Frank
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