SUBROUTINE LAP

PURPOSE
   COMPUTE THE VALUES OF THE LAGUERRE POLYNOMIALS L(N,X)
   FOR ARGUMENT VALUE X AND ORDERS 0 UP TO N.

USAGE
   CALL LAP(Y,X,N)

DESCRIPTION OF PARAMETERS
   Y	 - RESULT VECTOR OF DIMENSION N+1 CONTAINING THE VALUES
	   OF LAGUERRE POLYNOMIALS OF ORDER 0 UP TO N
	   FOR GIVEN ARGUMENT X.
	   VALUES ARE ORDERED FROM LOW TO HIGH ORDER
   X	 - ARGUMENT OF LAGUERRE POLYNOMIAL
   N	 - ORDER OF LAGUERRE POLYNOMIAL

REMARKS
   N LESS THAN 0 IS TREATED AS IF N WERE 0

SUBROUTINES AND FUNCTION SUBPROGRAMS REQUIRED
   NONE

METHOD
   EVALUATION IS BASED ON THE RECURRENCE EQUATION FOR
   LAGUERRE POLYNOMIALS L(N,X)
   L(N+1,X)=2*L(N,X)-L(N-1,X)-((1+X)*L(N,X)-L(N-1,X))/(N+1),
   WHERE THE FIRST TERM IN BRACKETS IS THE ORDER,
   THE SECOND IS THE ARGUMENT.
   STARTING VALUES ARE L(0,X)=1, L(1,X)=1.-X.