C DAPS 10
C ..................................................................DAPS 20
C DAPS 30
C SUBROUTINE DLAPS DAPS 40
C DAPS 50
C PURPOSE DAPS 60
C COMPUTES THE VALUE OF AN N-TERM EXPANSION IN LAGUERRE DAPS 70
C POLYNOMIALS WITH COEFFICIENT VECTOR C FOR ARGUMENT VALUE X. DAPS 80
C DAPS 90
C USAGE DAPS 100
C CALL DLAPS(Y,X,C,N) DAPS 110
C DAPS 120
C DESCRIPTION OF PARAMETERS DAPS 130
C Y - RESULT VALUE DAPS 140
C DOUBLE PRECISION VARIABLE DAPS 150
C X - ARGUMENT VALUE DAPS 160
C DOUBLE PRECISION VARIABLE DAPS 170
C C - COEFFICIENT VECTOR OF GIVEN EXPANSION DAPS 180
C COEFFICIENTS ARE ORDERED FROM LOW TO HIGH DAPS 190
C DOUBLE PRECISION VECTOR DAPS 200
C N - DIMENSION OF COEFFICIENT VECTOR C DAPS 210
C DAPS 220
C REMARKS DAPS 230
C OPERATION IS BYPASSED IN CASE N LESS THAN 1 DAPS 240
C DAPS 250
C SUBROUTINES AND FUNCTION SUBPROGRAMS REQUIRED DAPS 260
C NONE DAPS 270
C DAPS 280
C METHOD DAPS 290
C DEFINITION DAPS 300
C Y=SUM(C(I)*L(I-1,X), SUMMED OVER I FROM 1 TO N). DAPS 310
C EVALUATION IS DONE BY MEANS OF UPWARD RECURSION DAPS 320
C USING THE RECURRENCE EQUATION FOR LAGUERRE POLYNOMIALS DAPS 330
C L(N+1,X)=2*L(N,X)-L(N-1,X)-((1+X)*L(N,X)-L(N-1,X))/(N+1). DAPS 340
C DAPS 350
C ..................................................................DAPS 360
C DAPS 370
SUBROUTINE DLAPS(Y,X,C,N) DAPS 380
C DAPS 390
DIMENSION C(1) DAPS 400
DOUBLE PRECISION C,Y,X,H0,H1,H2,T DAPS 410
C DAPS 420
C TEST OF DIMENSION DAPS 430
IF(N)1,1,2 DAPS 440
1 RETURN DAPS 450
C DAPS 460
2 Y=C(1) DAPS 470
IF(N-2)1,3,3 DAPS 480
C DAPS 490
C INITIALIZATION DAPS 500
3 H0=1.D0 DAPS 510
H1=1.D0-X DAPS 520
T=1.D0+X DAPS 530
DO 4 I=2,N DAPS 540
H2=H1-H0+H1-(T*H1-H0)/DFLOAT(I) DAPS 550
H0=H1 DAPS 560
H1=H2 DAPS 570
4 Y=Y+C(I)*H0 DAPS 580
RETURN DAPS 590
END DAPS 600