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### IMSL_BETA

IMSL_BETA

The IMSL_BETA function evaluates the real beta function b(x, y).]

## Syntax

Result = IMSL_BETA(x, y [, /DOUBLE])

## Return Value

The value of the beta function b(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

If present and nonzero, double precision is used.

## Discussion

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

requiring that x > 0 and y > 0. It underflows for large parameters.

## Example

Plot the beta function over [e, 1/4 + e] x [e, 1/4 + e] for e = 0.01. The results are shown in Figure 12-5.

`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.  `

Figure 12-5: Real Beta Function Plot

## 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.

## Version History

 6.4 Introduced

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