comp.lang.idl-pvwave archive: archive » Re: Exponential of very small numbers

Home » Public Forums » archive » Re: Exponential of very small numbers

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

Re: Exponential of very small numbers [message #84279]

Wed, 08 May 2013 10:40

Jacopo D
Messages: 2
Registered: May 2013

Junior Member

Thank you Wayne, it works!!

Report message to a moderator

Re: Exponential of very small numbers [message #84280 is a reply to message #84279]

Wed, 08 May 2013 09:42

wlandsman
Messages: 743
Registered: June 2000

Senior Member

For x very close to zero I would use the approximation
exp(x) = x

or you could display all the digits (and use double precision)

IDL> print,EXP(1.6671699d-013)-1
1.6675550e-13
IDL> print,EXP(1.6671699d-013),f='(f24.18)'
1.000000000000166755

--Wayne

On Wednesday, May 8, 2013 12:14:19 PM UTC-4, Jacopo D wrote:
> Hello, first post ;)
>
> i need to integrate the planck distribution on IDL, but i have a problem with the exponential.
>
> The error is:
>
> EXP(1.6671699e-013)=1
>
>
>
> What can i do to avoid this problem? Even if it's an exponent very close to zero, it's important for my code.
>
> Thanks!

Report message to a moderator

Previous Topic:	Exponential of very small numbers
Next Topic:	IDL Workbench & jumping back to STOP/breakpoints

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Wed Oct 08 13:33:48 PDT 2025

Total time taken to generate the page: 0.00370 seconds