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