RPZERO(3)

SYNOPSIS
SUBROUTINE RPZERO (N, A, R, T, IFLG, S)

NAME
rpzero - Find the zeros of a polynomial with real coefficients.

LIBRARY
SLATEC

CATEGORY
F1A1A

TYPE
SINGLE PRECISION (RPZERO-S, CPZERO-C)

KEYWORDS
POLYNOMIAL ROOTS, POLYNOMIAL ZEROS, REAL ROOTS

AUTHOR
Kahaner, D. K., (NBS)

DESCRIPTION
Find the zeros of the real polynomial P(X)= A(1)*X**N + A(2)*X**(N-1) +...+ A(N+1) Input... N = degree of P(X) A = real vector containing coefficients of P(X), A(I) = coefficient of X**(N+1-I) R = N word complex vector containing initial estimates for zeros if these are known. T = 6(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
CPZERO

REVISION HISTORY (YYMMDD)
810223 DATE WRITTEN
890206 REVISION DATE from Version 3.2
891214 Prologue converted to Version 4.0 format. (BAB)