◆ rpzero2()

Roots of a polynomial (real coefficients) (Simultaneous iteration for all roots) (Complex type is not used)

Purpose: rpzero2 computes all roots of a polynomial p(z) with real coefficients by the iterative method finding all roots simultaneously.
p(z) = a0*z^n + a1*z^(n-1) + ... + an

The obtained zeros are output to the separate real type variables for real and imaginary parts.

Parameters

[in]	n	Degree of polynomial. (n >= 1)
[in]	a[]	Array a[la] (la >= n + 1) Real coefficient vector of p(z) (a0 to an).
[in,out]	rr[]	Array rr[lrr] (lrr >= n) [in] Real parts of initial estimates for zeros. If these are unknown, set iflag = 0 and it is not necessary to set estimates in rr[]. Note - Initial estimates must be separated, that is, distinct or not repeated. [out] Real part of the obtained zeros.
[in,out]	ri[]	Array ri[lri] (lri >= n) [in] Imaginary parts of initial estimates for zeros. If these are unknown, set iflag = 0 and it is not necessary to set estimates in ri[]. Note - Initial estimates must be separated, that is, distinct or not repeated. [out] Imaginary part of the obtained zeros.
[in]	iflag	Flag to indicate if initial estimates of zeros are input. = 0: No estimates are input. != 0: rr[] and ri[] contain estimates of zeros.
[in]	maxiter	Maximum number of iterations. (maxitr >= 1)
[out]	iter	Number of iterations required to converge.
[out]	s[]	Array s[ls] (ls >= n) Error bound for the obtained zeros.
[out]	work[]	Array work[lwork] (lwork >= 8*n + 6) Work array.
[out]	info	= 0: Successful exit = -1: The argument n had an illegal value (n < 1) = -2: The argument a had an illegal value (a[0] = 0) = -6: The argument maxiter had an illegal value (maxiter <= 0) = 1: Failed to converge after maxiter iterations. Best current estimates of the zeros are in rr[] and ri[]. Error bounds in s[] are not calculated.