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