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