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