This function computes the binomial probability for a given range. The parameters passed are the minimum and maximum for the range (inclusive), the population size, and the success probability.
If you are not familiar with the binomial distribution please visit http://en.wikipedia.org/wiki/Binomial_distribution for more information.

For example if you call binom_range(5,10,15,.5) it will compute the sum of the binomial distribution from 5 to 10 with the total population size of 15 and success probability of .5. Some examples are also run in the file.