Function _numRoots

SLiCAP/SLiCAPmath.py:198–232

Returns the roots of the polynomial 'expr' with indeterminate 'var'. This function uses numpy for calculation of numeric roots. :note: See: https://docs.scipy.org/doc/numpy/reference/generated/numpy.polynomial.polynomial.polyroots.html :param expr: Univariate function. :

(expr, var)

    return rts

def _numRoots(expr, var):
    """
    Returns the roots of the polynomial 'expr' with indeterminate 'var'.

    This function uses numpy for calculation of numeric roots.

    :note:

    See: https://docs.scipy.org/doc/numpy/reference/generated/numpy.polynomial.polynomial.polyroots.html

    :param expr: Univariate function.
    :type expr: sympy.Expr

    :param var: Indeterminate of 'expr'.
    :type var: sympy.Symbol
    """
    rts = []
    try:
        pol = sp.Poly(expr, var)
        coeffs = pol.all_coeffs()
        coeffs = [float(sp.N(coeffs[i]/sp.Poly.LC(pol))) for i in range(len(coeffs))]
    except sp.PolynomialError:
        print('ERROR: could not write expression as polynomial:\n\n')
        print('Try different setting for setting: ini.numer and/or ini.denom;')
        print('current settings: ', ini.numer, ini.denom, 'respectively.')
        coeffs = []
    coeffs = np.array(coeffs[::-1], dtype=float) # Reversed list to array
    try:
        p = Polynomial(coeffs)
        rts = np.flip(p.roots())
    except BaseException:
        exc_type, value, exc_traceback = sys.exc_info()
        print('\n', value)
        print("Error: cannot determine the roots of:", str(p))
    return rts

def coeffsTransfer(rational, var=ini.laplace, method='lowest'):
    """