Manuals/calci/BETAINV

BETAINV(prob,alpha,beta,a,b)

$prob$ is the probability value associated with the beta distribution.
$alpha$ & $beta$ are the values of the shape parameter.
$a$ & $b$ the lower and upper limit to the interval of $x$ .

Description

This function gives the inverse value of Cumulative Beta Probability Distribution.
It is called Inverted Beta Function or Beta Prime.
In $BETAINV(prob,alpha,beta,a,b)$ , $prob$ is the probability value associated with Beta Distribution, $alpha$ and $beta$ are the values of two positive shape parameters and $a$ and $b$ are the lower and upper limit.
Normally the limit values are optional, i.e. when we are giving the values of $a$ & $b$ then the result value is from $a$ and $b$ .
When we are omitting the values $a$ and $b$ , by default it will consider $a=0$ and $b=1$ , so the result value is from $0$ and $1$ .
If $BETADIST(x,alpha,beta,a,b)=prob$ , then $BETAINV(prob,alpha,beta,a,b)=x$ .
$BETAINV$ use the iterating method to find the value of $x$ .suppose the iteration has not converged after 100 searches, then the function gives the error result.
This function will give the error result when

1.Any one of the arguments are non-numeric
2. $\alpha$  or  $\beta \leq 0$ 
3. $x<a,x>b$  or  $a=b$ 
4.we are not mentioning the limit values  for  $a$ & $b$ , 
  by default it will consider the Standard Cumulative Beta Distribution,  $a=0$  and b = 1