I'm actually on vacation this week, but last night I showed a friend how to write software in Scala. He's familiar with recursion, so we jumped right into a simple factorial recursion example:
Still reading Calculus Made Easy, they note that 'e' (the natural logarithm, or natural log) is the limit of the following series:
1 + 1/1! + 1/2! + 1/3! ...
To test this I created the following Ruby natural log program.