costmi

NAME

SYNOPSIS

 SUBROUTINE COSTMI (N, WSAVE, LENSAV, IER)
 INTEGER    N, LENSAV, IER
 REAL       WSAVE(LENSAV)
 

DESCRIPTION

 FFTPACK 5.0 subroutine COSTMI initializes array WSAVE for use
 in its companion routines COSTMF and COSTMB.  The prime factor-
 ization of N together with a tabulation of the trigonometric
 functions are computed and stored in array WSAVE.  Separate
 WSAVE arrays are required for different values of N.
 
 Input Arguments
 
 N       Integer length of each sequence to be transformed.  The 
         transform is most efficient when N is a product of 
         small primes.
 
 LENSAV  Integer dimension of WSAVE array.  LENSAV must be at least 
         2*N + INT(LOG (REAL(N))) +4


 Output Arguments
 
 WSAVE   Real work array with dimension LENSAV, containing the
         prime factors of N and also containing certain trigonometric 
         values which will be used in routines COSTMB or COSTMF.


 IER     Integer error return
         =  0 successful exit
         =  2 input parameter LENSAV not big enough
         = 20 input error returned by lower level routine