SUBROUTINE CHEBY (CH,DC,M,N,X,XP)                                SUBR3123
C                                                                       SUBR3124
C                                                                       SUBR3125
C             WRITTEN  BY  P. LAWNIKANIS         MARCH 1974.            SUBR3126
C                                                                       SUBR3127
C                                                                       SUBR3128
C   ›CHEBY› COMPUTES N-1ST CHEBYSHEV POLYNOMIALS                        SUBR3129
C           FOR ARGUEMENT ›X› IN VECTOR ›CH›.                           SUBR3130
C           DERIVATIVE POLYNOMIALS IN ›DC› FOR                          SUBR3131
C           ›X› DERIVATIVE ›XP› IF ›J› = 1.                             SUBR3132
C                                                                       SUBR3133
C                                                                       SUBR3134
      IMPLICIT REAL*8(A-H,O-Z)                                                  
       DIMENSION DC(N),CH(N)                                            SUBR3135
       IF (N) 10,10,20                                                  SUBR3136
   10  RETURN                                                           SUBR3137
C                                                                       SUBR3138
   20  CH(1) = 1.                                                       SUBR3139
       CH(2) = X                                                        SUBR3140
       IF (N.LT.3) RETURN                                               SUBR3141
       TX = X + X                                                       SUBR3142
           DO 100 I = 3,N                                               SUBR3143
               CH(I) = CH(I-1) * TX - CH(I-2)                           SUBR3144
  100      CONTINUE                                                     SUBR3145
       IF (M.NE.1) RETURN                                               SUBR3146
C                                                                       SUBR3147
       DC(1) = 0.                                                       SUBR3148
       DC(2) = XP                                                       SUBR3149
       DC(3) = (TX + TX) * XP                                           SUBR3150
       IF (N.LT.4) RETURN                                               SUBR3151
           DO 200 I = 4,N                                               SUBR3152
               J = I - 1                                                SUBR3153
               K = I - 2                                                SUBR3154
               DC(I) = DC(J) * FLOAT(J) / FLOAT(K) * TX                 SUBR3155
     !               - DC(K) * FLOAT(J) / FLOAT(K-1)                    SUBR3156
  200      CONTINUE                                                     SUBR3157
       RETURN                                                           SUBR3158
C                                                                       SUBR3159
       END                                                              SUBR3160