cpqr79 cpzero dka rpqr79 rpzero rpzero2

rpzero() void rpzero ( int  n, double  a[], doublecomplex  r[], int  iflag, int  maxiter, int *  iter, double  s[], doublecomplex  work[], int *  info  ) Roots of a polynomial (real coefficients) (Simultaneous iteration for all roots) Purpose rpzero 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 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] r[] Array r[lr] (lr >= n) [in] Initial estimates for zeros. If these are unknown, set iflag = 0 and it is not necessary to set estimates in r[].   Note - Initial estimates must be separated, that is, distinct or not repeated. [out] The obtained zeros. [in] iflag Flag to indicate if initial estimates of zeros are input. = 0: No estimates are input. != 0: r[] contains 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 >= 3*(n + 1)) 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) = -5: The argument maxiter had an illegal value (maxiter <= 0) = 1: Failed to converge after maxiter iterations. Best current estimates of the zeros are in r[]. Error bounds in s[] are not calculated. Reference SLATEC