share/fftpack5/fortran/sinq1f.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 SINQ1F ( N, INC, X, LENX, WSAVE, LENSAV,
  12      1                   WORK, LENWRK, IER)
  13       INTEGER    N, INC, LENX, LENSAV, LENWRK, IER
  14       REAL       X(INC,*), WSAVE(LENSAV), WORK(LENWRK)
  15 C
  16       IER = 0
  17 C
  18       IF (LENX .LT. INC*(N-1) + 1) THEN
  19         IER = 1
  20         CALL XERFFT ('SINQ1F', 6)
  21         GO TO 300
  22       ELSEIF (LENSAV .LT. 2*N + INT(LOG(REAL(N))/LOG(2.)) +4) THEN
  23         IER = 2
  24         CALL XERFFT ('SINQ1F', 8)
  25         GO TO 300
  26       ELSEIF (LENWRK .LT. N) THEN
  27         IER = 3
  28         CALL XERFFT ('SINQ1F', 10)
  29         GO TO 300
  30       ENDIF
  31 C
  32       IF (N .EQ. 1) RETURN
  33       NS2 = N/2
  34       DO 101 K=1,NS2
  35          KC = N-K
  36          XHOLD = X(1,K)
  37          X(1,K) = X(1,KC+1)
  38          X(1,KC+1) = XHOLD
  39   101 CONTINUE
  40       CALL COSQ1F (N,INC,X,LENX,WSAVE,LENSAV,WORK,LENWRK,IER1)
  41       IF (IER1 .NE. 0) THEN
  42         IER = 20
  43         CALL XERFFT ('SINQ1F',-5)
  44         GO TO 300
  45       ENDIF
  46       DO 102 K=2,N,2
  47          X(1,K) = -X(1,K)
  48   102 CONTINUE
  49   300 RETURN
  50       END