C DEPS 10
C ..................................................................DEPS 20
C DEPS 30
C SUBROUTINE DLEPS DEPS 40
C DEPS 50
C PURPOSE DEPS 60
C COMPUTES THE VALUE OF AN N-TERM EXPANSION IN LEGENDRE DEPS 70
C POLYNOMIALS WITH COEFFICIENT VECTOR C FOR ARGUMENT VALUE X. DEPS 80
C DEPS 90
C USAGE DEPS 100
C CALL DLEPS(Y,X,C,N) DEPS 110
C DEPS 120
C DESCRIPTION OF PARAMETERS DEPS 130
C Y - RESULT VALUE DEPS 140
C DOUBLE PRECISION VARIABLE DEPS 150
C X - ARGUMENT VALUE DEPS 160
C DOUBLE PRECISION VARIABLE DEPS 170
C C - COEFFICIENT VECTOR OF GIVEN EXPANSION DEPS 180
C COEFFICIENTS ARE ORDERED FROM LOW TO HIGH DEPS 190
C DOUBLE PRECISION VECTOR DEPS 200
C N - DIMENSION OF COEFFICIENT VECTOR C DEPS 210
C DEPS 220
C REMARKS DEPS 230
C OPERATION IS BYPASSED IN CASE N LESS THAN 1 DEPS 240
C DEPS 250
C SUBROUTINES AND FUNCTION SUBPROGRAMS REQUIRED DEPS 260
C NONE DEPS 270
C DEPS 280
C METHOD DEPS 290
C DEFINITION DEPS 300
C Y=SUM(C(I)*P(I-1,X), SUMMED OVER I FROM 1 TO N). DEPS 310
C EVALUATION IS DONE BY MEANS OF UPWARD RECURSION DEPS 320
C USING THE RECURRENCE EQUATION FOR LEGENDRE POLYNOMIALS DEPS 330
C P(N+1,X)=2*X*P(N,X)-P(N-1,X)-(X*P(N,X)-P(N-1,X))/(N+1). DEPS 340
C DEPS 350
C ..................................................................DEPS 360
C DEPS 370
SUBROUTINE DLEPS(Y,X,C,N) DEPS 380
C DEPS 390
DIMENSION C(1) DEPS 400
DOUBLE PRECISION C,Y,X,H0,H1,H2 DEPS 410
C DEPS 420
C TEST OF DIMENSION DEPS 430
IF(N)1,1,2 DEPS 440
1 RETURN DEPS 450
C DEPS 460
2 Y=C(1) DEPS 470
IF(N-2)1,3,3 DEPS 480
C DEPS 490
C INITIALIZATION DEPS 500
3 H0=1.D0 DEPS 510
H1=X DEPS 520
C DEPS 530
DO 4 I=2,N DEPS 540
H2=X*H1 DEPS 550
H2=H2-H0+H2-(H2-H0)/DFLOAT(I) DEPS 560
H0=H1 DEPS 570
H1=H2 DEPS 580
4 Y=Y+C(I)*H0 DEPS 590
RETURN DEPS 600
END DEPS 610