LNBETA Function
Evaluates the logarithm of the real beta function ln β(x, y).
Usage
result = LNBETA(x, y)
Input Parameters
x—First argument of the beta function. It must be positive.
y—Second argument of the beta function. It must be positive.
Returned Value
result—The value of the logarithm of the beta function β(x, y).
Input Keywords
Double—If present and nonzero, double precision is used.
Discussion
The beta function, β(x, y), is defined as:
and LNBETA returns ln β(x, y). The logarithm of the beta function requires that x > 0 and y > 0. It can overflow for very large parameters.
Example
Evaluate the log of the beta function ln β (0.5, 0.2).
PM, LNBETA(.5, .2) ; PV-WAVE prints: 1.83556
Warning Errors
MATH_X_IS_TOO_CLOSE_TO_NEG_1—Result is accurate to less than one precision because the expression –x / (x + y) is too close to –1.
