IMSL_LNBETA

The IMSL_LNBETA function evaluates the logarithm of the real beta function ln β(x, y).

This routine requires an IDL Advanced Math and Stats license. For more information, contact your sales or technical support representative.

The beta function, β(x, y), is defined as:

and IMSL_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, IMSL_LNBETA(.5, .2)

1.83556

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.

Result = IMSL_LNBETA(x, y [, /DOUBLE])

The value of the logarithm of the beta function β(x, y).

First argument of the beta function. It must be positive.

Second argument of the beta function. It must be positive.

If present and nonzero, double precision is used.

6.4	Introduced