MATLAB Function Reference

betaln

Logarithm of beta function

Syntax

• L = betaln(Z,W)
  

Description

L = betaln(Z,W) computes the natural logarithm of the beta function log(beta(Z,W)), for corresponding elements of arrays Z and W, without computing beta(Z,W). Since the beta function can range over very large or very small values, its logarithm is sometimes more useful.

Z and W must be real and nonnegative. They must be the same size, or either can be scalar.

Examples

• x = 510
  betaln(x,x)
  
  ans = 
        -708.8616
  

-708.8616 is slightly less than log(realmin). Computing beta(x,x) directly would underflow (or be denormal).

Algorithm

• betaln(z,w) = gammaln(z)+gammaln(w)-gammaln(z+w)
  

See Also

beta, betainc, gammaln

betainc

bicg