**Public Function RD( _
ByVal vX As Variant _
, ByVal vY As Variant _
, ByVal vZ As Variant _
) As Variant**

**Compute the incomplete or complete elliptic integral of the 2nd kind. **

**Examples:** RD(1, 1, 3) = 0.349720080430692
RD(1, 2, 3) = 0.290460281028991
RD(2, 1, 3) = 0.290460281028991
RD(2, 2, 3) = 0.243386037818348

**See also:** RC Function
RF Function
RJ Function
DRD Function

**vX:** Function returns Null if vX is Null or cannot be fixed up to a Double precision floating point number.

**vY:** Function returns Null if vY is Null or cannot be fixed up to a Double precision floating point number.

**vZ:** Function returns Null if vZ is Null or cannot be fixed up to a Double precision floating point number. For X and Y nonnegative, X+Y and Z positive, RD(X,Y,Z) = Integral from zero to infinity of (3/2)(t+X)^(-1/2)(t+Y)^(-1/2)(t+Z)^(-3/2) dt. If X or Y is zero, the integral is complete.

Evaluate an INCOMPLETE (or COMPLETE) ELLIPTIC INTEGRAL of the second kind.

The routine calculates an approximation result to RD(X,Y,Z) = Integral from zero to infinity of

-1/2 -1/2 -3/2
(3/2)(t+X) (t+Y) (t+Z) dt,

where X and Y are nonnegative, X + Y is positive, and Z is positive. If X or Y is zero, the integral is COMPLETE. The duplication theorem is iterated until the variables are nearly equal, and the function is then expanded in Taylor series to fifth order. Copyright 1996-1999 Entisoft

Entisoft Tools is a trademark of Entisoft.