C DAP 10
C ..................................................................DAP 20
C DAP 30
C SUBROUTINE DLAP DAP 40
C DAP 50
C PURPOSE DAP 60
C COMPUTE THE VALUES OF THE LAGUERRE POLYNOMIALS L(N,X) DAP 70
C FOR ARGUMENT VALUE X AND ORDERS 0 UP TO N. DAP 80
C DAP 90
C USAGE DAP 100
C CALL DLAP(Y,X,N) DAP 110
C DAP 120
C DESCRIPTION OF PARAMETERS DAP 130
C Y - RESULT VECTOR OF DIMENSION N+1 CONTAINING THE VALUESDAP 140
C OF LAGUERRE POLYNOMIALS OF ORDER 0 UP TO N DAP 150
C FOR GIVEN ARGUMENT X. DAP 160
C DOUBLE PRECISION VECTOR. DAP 170
C VALUES ARE ORDERED FROM LOW TO HIGH ORDER DAP 180
C X - ARGUMENT OF LAGUERRE POLYNOMIAL DAP 190
C DOUBLE PRECISION VARIABLE. DAP 200
C N - ORDER OF LAGUERRE POLYNOMIAL DAP 210
C DAP 220
C REMARKS DAP 230
C N LESS THAN 0 IS TREATED AS IF N WERE 0 DAP 240
C DAP 250
C SUBROUTINES AND FUNCTION SUBPROGRAMS REQUIRED DAP 260
C NONE DAP 270
C DAP 280
C METHOD DAP 290
C EVALUATION IS BASED ON THE RECURRENCE EQUATION FOR DAP 300
C LAGUERRE POLYNOMIALS L(N,X) DAP 310
C L(N+1,X)=2*L(N,X)-L(N-1,X)-((1+X)*L(N,X)-L(N-1,X))/(N+1), DAP 320
C WHERE THE FIRST TERM IN BRACKETS IS THE ORDER, DAP 330
C THE SECOND IS THE ARGUMENT. DAP 340
C STARTING VALUES ARE L(0,X)=1, L(1,X)=1.-X. DAP 350
C DAP 360
C ..................................................................DAP 370
C DAP 380
SUBROUTINE DLAP(Y,X,N) DAP 390
C DAP 400
DIMENSION Y(1) DAP 410
DOUBLE PRECISION Y,X,T DAP 420
C DAP 430
C TEST OF ORDER DAP 440
Y(1)=1.D0 DAP 450
IF(N)1,1,2 DAP 460
1 RETURN DAP 470
C DAP 480
2 Y(2)=1.D0-X DAP 490
IF(N-1)1,1,3 DAP 500
C DAP 510
C INITIALIZATION DAP 520
3 T=1.D0+X DAP 530
C DAP 540
DO 4 I=2,N DAP 550
4 Y(I+1)=Y(I)-Y(I-1)+Y(I)-(T*Y(I)-Y(I-1))/DFLOAT(I) DAP 560
RETURN DAP 570
END DAP 580