Remove small leading coefficients

Remove leading coefficients until a coefficient is reached whose absolute value greater than tol or the beginning of the series is reached. If all the coefficients would be removed the series is set to [0]. A new Polynomial instance is returned with the new coefficients. The current instance remains unchanged.

Parameters :

tol : non-negative number.

All trailing coefficients less than tol will be removed.

Returns :

new_instance : Polynomial

Contains the new set of coefficients.