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IMSL_BETA

IMSL_BETA

The IMSL_BETA function evaluates the real beta function 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:

requiring that X > 0 and Y > 0. It underflows for large parameters.

Example


Plot the beta function over [ε, 1/4 + ε] x [ε, 1/4 + ε] for ε = 0.01. The results are shown in the Real Beta Function Plot after the code example.

x = 1e-2 + .25 * FINDGEN(25)/24 y = x
b = FLTARR(25, 25)
FOR i = 0, 24 DO b(i, *) = IMSL_BETA(x(i), y)
; Compute values of the beta function.
SURFACE, b, x, y, XTitle = 'X', YTitle = 'Y', Az = 320, ZAxis = 2
; Plot the computed values as a surface and rotate the plot.

Errors


Alert Errors

MATH_BETA_UNDERFLOW: Parameters must not be so large that the result underflows.

Fatal Errors

MATH_ZERO_ARG_OVERFLOW: One of the parameters is so close to zero that the result overflows.

Syntax


Result = IMSL_BETA(X, Y [, /DOUBLE])

Return Value


The value of the beta function β(x, y). If no result can be computed, then NaN (Not a Number) is returned.

Arguments


X

First beta parameter. It must be positive.

Y

Second beta parameter. It must be positive.

Keywords


DOUBLE (optional)

If present and nonzero, double precision is used.

Version History


6.4

Introduced

See Also


IMSL_BETACDF, IMSL_BETAI



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