CPZERO(3)

SYNOPSIS
SUBROUTINE CPZERO (IN, A, R, T, IFLG, S)

NAME
cpzero - Find the zeros of a polynomial with complex coefficients.

LIBRARY
SLATEC

CATEGORY
F1A1B

TYPE
COMPLEX (RPZERO-S, CPZERO-C)

KEYWORDS
POLYNOMIAL ROOTS, POLYNOMIAL ZEROS, REAL ROOTS

AUTHOR
Kahaner, D. K., (NBS)

DESCRIPTION
Find the zeros of the complex polynomial P(Z)= A(1)*Z**N + A(2)*Z**(N-1) +...+ A(N+1) Input... IN = degree of P(Z) A = complex vector containing coefficients of P(Z), A(I) = coefficient of Z**(N+1-i) R = N word complex vector containing initial estimates for zeros if these are known. T = 4(N+1) word array used for temporary storage IFLG = flag to indicate if initial estimates of zeros are input. If IFLG .EQ. 0, no estimates are input. If IFLG .NE. 0, the vector R contains estimates of the zeros ** WARNING ****** If estimates are input, they must be separated, that is, distinct or not repeated. S = an N word array Output... R(I) = Ith zero, S(I) = bound for R(I) . IFLG = error diagnostic Error Diagnostics... If IFLG .EQ. 0 on return, all is well If IFLG .EQ. 1 on return, A(1)=0.0 or N=0 on input If IFLG .EQ. 2 on return, the program failed to converge after 25*N iterations. Best current estimates of the zeros are in R(I). Error bounds are not calculated.

REFERENCES
(NONE)

ROUTINES CALLED
CPEVL

REVISION HISTORY (YYMMDD)
810223 DATE WRITTEN
890531 Changed all specific intrinsics to generic. (WRB)
890531 REVISION DATE from Version 3.2
891214 Prologue converted to Version 4.0 format. (BAB)