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IMSL_LNBETA

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

Errors


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.

Syntax


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

Return Value


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

Arguments


X

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

Y

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

Keywords


DOUBLE (optional)

If present and nonzero, double precision is used.

Version History


6.4

Introduced



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