share/fftpack5/fortran/cosq1i.f

   1 CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
   2 C
   3 C   FFTPACK 5.0
   4 C
   5 C   Authors:  Paul N. Swarztrauber and Richard A. Valent
   6 C
   7 C   $Id$
   8 C
   9 CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
  10
  11       SUBROUTINE COSQ1I (N, WSAVE, LENSAV, IER)
  12       INTEGER    N, LENSAV, IER
  13       REAL       WSAVE(LENSAV)
  14 C
  15       IER = 0
  16       IF (LENSAV .LT. 2*N + INT(LOG(REAL(N))/LOG(2.)) +4) THEN
  17         IER = 2
  18         CALL XERFFT ('COSQ1I', 3)
  19         GO TO 300
  20       ENDIF
  21 C
  22       PIH = 2.*ATAN(1.)
  23       DT = PIH/FLOAT(N)
  24       FK = 0.
  25       DO 101 K=1,N
  26          FK = FK+1.
  27          WSAVE(K) = COS(FK*DT)
  28   101 CONTINUE
  29       LNSV = N + INT(LOG(REAL(N))/LOG(2.)) +4
  30       CALL RFFT1I (N, WSAVE(N+1), LNSV, IER1)
  31       IF (IER1 .NE. 0) THEN
  32         IER = 20
  33         CALL XERFFT ('COSQ1I',-5)
  34       ENDIF
  35   300 CONTINUE
  36       RETURN
  37       END