| Author(s): T. Pomentale | Library: MATHLIB |
| Submitter: K.S. Kölbig | Submitted: 07.06.1992 |
| Language: Fortran | Revised: |
Subroutine subprograms CPOLYZ and WPOLYZ compute the zeros of the polynominal
of degree n with complex coefficients 
and 
.
On computers other than CDC or Cray, only the double-precision version WPOLYZ is available. On CDC and Cray computers, only the single-precision version CPOLYZ is available.
Structure:
SUBROUTINE subprograms
User Entry Names: CPOLYZ, WPOLYZ
Files Referenced: Unit 6
External References: MTLMTR, ABEND
Usage:
For 
(type COMPLEX), 
(type
COMPLEX*16),
CALL tPOLYZ(C,N,MAXIT,Z,R)
, containing the
coefficients 
.
. On entry, 
must contain
starting approximations for the zeros 
. If no starting
approximations are available, the 
should be set
to zero. On exit, 
contains an approximation to the zero
.
, DOUBLE PRECISION for
) One-dimensional array of dimension 
.
On exit, 
contain an estimated radius 
of a circle centered at 
within which the true zero
is expected to lie.
Notes:
Note that, because of accumulation of rounding errors, unreliable results can be obtained for large n even for well-conditioned polynomials.
Error handling:
Error C209.1: 
.
Error C209.2: The number of iterations exceeds MAXIT.
Error C209.3: An estimated radius 
cannot be computed for a
certain value of i.
In all cases, a message is written on Unit 6,
unless subroutine MTLSET (N002) has been called.
References:
