def __nonzero__(self):  
return not bool(<EOL>np.all(<EOL>np.isclose(<EOL>self._dep_vector, np.zeros(len(self._dep_vector)), FP_RTOL, FP_ATOL<EOL>)<EOL>)<EOL>)<EOL>
Test if the waveform dependent vector is zero for all its elements.

For example:

    >>> import numpy as np
    >>> import peng
    >>> indep_vector = np.array([1, 2, 3])
    >>> dep_vector = np.array([4, 5, 6])
    >>> obj = peng.Waveform(indep_vector, dep_vector, 'obj_a')
    >>> if obj:
    ...     print('Boolean test returned: True')
    ... else:
    ...     print('Boolean test returned: False')
    Boolean test returned: True
    >>> dep_vector = np.zeros(3)
    >>> obj = peng.Waveform(indep_vector, dep_vector, 'obj_a')
    >>> if obj:
    ...     print('Boolean test returned: True')
    ... else:
    ...     print('Boolean test returned: False')
    Boolean test returned: False