C CNPS 10
C ..................................................................CNPS 20
C CNPS 30
C SUBROUTINE CNPS CNPS 40
C CNPS 50
C PURPOSE CNPS 60
C COMPUTES THE VALUE OF AN N-TERM EXPANSION IN CHEBYSHEV CNPS 70
C POLYNOMIALS WITH COEFFICIENT VECTOR C FOR ARGUMENT VALUE X. CNPS 80
C CNPS 90
C USAGE CNPS 100
C CALL CNPS(Y,X,C,N) CNPS 110
C CNPS 120
C DESCRIPTION OF PARAMETERS CNPS 130
C Y - RESULT VALUE CNPS 140
C X - ARGUMENT VALUE CNPS 150
C C - COEFFICIENT VECTOR OF GIVEN EXPANSION CNPS 160
C COEFFICIENTS ARE ORDERED FROM LOW TO HIGH CNPS 170
C N - DIMENSION OF COEFFICIENT VECTOR C CNPS 180
C CNPS 190
C REMARKS CNPS 200
C OPERATION IS BYPASSED IN CASE N LESS THAN 1 CNPS 210
C CNPS 220
C SUBROUTINES AND FUNCTION SUBPROGRAMS REQUIRED CNPS 230
C NONE CNPS 240
C CNPS 250
C METHOD CNPS 260
C DEFINITION CNPS 270
C Y=SUM(C(I)*T(I-1,X), SUMMED OVER I FROM 1 TO N). CNPS 280
C EVALUATION IS DONE BY MEANS OF BACKWARD RECURSION CNPS 290
C USING THE RECURRENCE EQUATION FOR CHEBYSHEV POLYNOMIALS CNPS 300
C T(N+1,X)=2*X*T(N,X)-T(N-1,X). CNPS 310
C CNPS 320
C ..................................................................CNPS 330
C CNPS 340
SUBROUTINE CNPS(Y,X,C,N) CNPS 350
C CNPS 360
DIMENSION C(1) CNPS 370
C CNPS 380
C TEST OF DIMENSION CNPS 390
IF(N)1,1,2 CNPS 400
1 RETURN CNPS 410
C CNPS 420
2 IF(N-2)3,4,4 CNPS 430
3 Y=C(1) CNPS 440
RETURN CNPS 450
C CNPS 460
C INITIALIZATION CNPS 470
4 ARG=X+X CNPS 480
H1=0. CNPS 490
H0=0. CNPS 500
C CNPS 510
DO 5 I=1,N CNPS 520
K=N-I CNPS 530
H2=H1 CNPS 540
H1=H0 CNPS 550
5 H0=ARG*H1-H2+C(K+1) CNPS 560
Y=0.5*(C(1)-H2+H0) CNPS 570
RETURN CNPS 580
END CNPS 590