BetaDist  - script and chart function
                    BetaDist() returns the accumulated probability of the Beta distribution.
Syntax:
BetaDist(value, alpha, beta)
Return data type: number
| Argument | Description | 
|---|---|
| value | The value at which you want to evaluate the distribution. The value must be between 0 and 1. | 
| alpha | A positive number defining the first shape parameter. It is the exponent of the random variable | 
| beta | A positive number defining the second shape parameter. It is the exponent that controls the shape of the distribution. | 
This function is related 
			to the BetaInv function in the following way: 
If prob = BetaDist(value, alpha, beta), then BetaInv(prob, alpha, beta) = value