The IMSL_ELK function evaluates the complete elliptic integral of the kind K(x).

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

The complete elliptic integral of the first kind is defined to be:

The argument x must satisfy 0 ≤ x < 1; otherwise, IMSL_ELK returns the largest representable floating-point number.

The function K(x) is computed using IMSL_ELRF and the relation K(x) = RF(0, 1 − x, 1).

Example

The integral K(0) is evaluated.

PRINT, IMSL_ELK(0.0)
  1.57080

Syntax

Result = IMSL_ELK(X [, /DOUBLE]

Return Value

The complete elliptic integral K(x).

Arguments

X

Argument for which the function value is desired.

Keywords

DOUBLE (optional)

If present and nonzero, double precision is used.

Version History

6.4

Introduced

See Also

IMSL_ELRF