B100: Binomial Coefficient

Author(s): K.S. Kölbig	Library: MATHLIB
Submitter:	Submitted: 15.02.1989
Language: Fortran	Revised: 15.11.1995

Function subprograms RBINOM and DBINOM calculate the binomial coefficient

for real x and integer k. Function subprogram KBINOM calculates the binomial coefficient only for integer x=n.

On CDC and Cray computers, the double-precision version DBINOM is not available.

Structure:

FUNCTION subprograms
User Entry Names: RBINOM, DBINOM, KBINOM
Obsolete User Entry Names: BINOM RBINOM
Files Referenced: Unit 6

Usage:

In any arithmetic expression,

RBINOM(X,K), DBINOM(X,K) or KBINOM(N,K)

has the value of the binomial coefficient. RBINOM is of type REAL, DBINOM is of type DOUBLE PRECISION and X has the same type as the function name. KBINOM, N and K are of type INTEGER.

Restrictions:

Function subprogram KBINOM can compute only binomial coefficients which lie in the integer range of the machine.

Accuracy:

Full machine accuracy.

Error handling:

If the result of KBINOM would lie outside the integer range of the machine, KBINOM is set equal to zero and an error message is printed.