C DNP 10
C ..................................................................DNP 20
C DNP 30
C SUBROUTINE DCNP DNP 40
C DNP 50
C PURPOSE DNP 60
C COMPUTE THE VALUES OF THE CHEBYSHEV POLYNOMIALS T(N,X) DNP 70
C FOR ARGUMENT VALUE X AND ORDERS 0 UP TO N. DNP 80
C DNP 90
C USAGE DNP 100
C CALL DCNP,Y,X,N) DNP 110
C DNP 120
C DESCRIPTION OF PARAMETERS DNP 130
C Y - RESULT VECTOR OF DIMENSION N+1 CONTAINING THE VALUESDNP 140
C OF CHEBYSHEV POLYNOMIALS OF ORDER 0 UP TO N DNP 150
C FOR GIVEN ARGUMENT X. DNP 160
C DOUBLE PRECISION VECTOR. DNP 170
C VALUES ARE ORDERED FROM LOW TO HIGH ORDER DNP 180
C Y - RESULT VALUE DNP 190
C DOUBLE PRECISION VARIABLE. DNP 200
C X - ARGUMENT OF CHEBYSHEV POLYNOMIAL DNP 210
C N - ORDER OF CHEBYSHEV POLYNOMIAL DNP 220
C DNP 230
C REMARKS DNP 240
C N LESS THAN 0 IS TREATED AS IF N WERE 0 DNP 250
C DNP 260
C SUBROUTINES AND FUNCTION SUBPROGRAMS REQUIRED DNP 270
C NONE DNP 280
C DNP 290
C METHOD DNP 300
C EVALUATION IS BASED ON THE RECURRENCE EQUATION FOR DNP 310
C CHEBYSHEV POLYNOMIALS T(N,X) DNP 320
C T(N+1,X)=2*X*T(N,X)-T(N-1,X), DNP 330
C WHERE THE FIRST TERM IN BRACKETS IS THE ORDER, DNP 340
C THE SECOND IS THE ARGUMENT. DNP 350
C STARTING VALUES ARE T(0,X)=1, T(1,X)=X. DNP 360
C DNP 370
C ..................................................................DNP 380
C DNP 390
SUBROUTINE DCNP(Y,X,N) DNP 400
C DNP 410
DIMENSION Y(1) DNP 420
DOUBLE PRECISION Y,X,F DNP 430
C DNP 440
Y(1)=1.D0 DNP 450
IF(N)1,1,2 DNP 460
1 RETURN DNP 470
C DNP 480
2 Y(2)=X DNP 490
IF(N-1)1,1,3 DNP 500
C DNP 510
C INITIALIZATION DNP 520
3 F=X+X DNP 530
C DNP 540
DO 4 I=2,N DNP 550
4 Y(I+1)=F*Y(I)-Y(I-1) DNP 560
RETURN DNP 570
END DNP 580