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## Re: [Help-gsl] Exponential calculation

**From**: |
Kevin Channon |

**Subject**: |
Re: [Help-gsl] Exponential calculation |

**Date**: |
Wed, 11 Feb 2009 13:19:00 +0000 |

Hi Ashish,
>* Is there any known mathematical method to calculate : exponential( -*
>* val), when val is too small number like -100*
You don't need gsl for this, just use the standard c library math.h (or
cmath in c++)
printf("%g\n", exp(-100));
returns the correct answer of 3.7e-44
There might be some penalty in terms of speed and accuracy, I don't
know, but it does return a value that should be at least in the ballpark
>
>* If there is any such instance during probability density function*
>* calculation when exp( - x2/ 2) is calculated, How to handle such events?*
You might need to clarify this a bit more, I'm not sure that I understand
what you're asking
Cheers,
Kevin
--
Kevin Channon
School of Chemistry
University of Bristol
UK