Expressing Functions as Sums in Mathematica: Sigma Notation Guide

[member 428835]

Does anyone know how to express a given function as a sum in mathematica using sigma notation? For example, I know how to make $e^x = 1 + x^2/2 + x^3/6 + x^4/24...$ but how would I have mathematica write it as $e^x = \Sigma_{n=0}^{\infty} x^n/n!$?

Thanks a ton!

 

[DrClaude]

I'm not sure what you want here. If you want to write the sum yourself, use

Sum[x^n/(n!),{n,0,Infinity}]

Or do you want Mathematica to tell you what the sum is, given $e^x$?

 

[member 428835]

I was trying to have mathematica tell me the sum given $e^x$ (or any other function for that matter.

Thanks for responding!

 

[DrClaude]

The only way I can think of to obtain this is using natural language input:

= e^x series representation

 

[member 428835]

thanks for your help!