numpy.RankWarning
- 
exception numpy.RankWarning[source]
- 
Issued by polyfitwhen the Vandermonde matrix is rank deficient.For more information, a way to suppress the warning, and an example of RankWarningbeing issued, seepolyfit.
    © 2005–2019 NumPy Developers
Licensed under the 3-clause BSD License.
    https://docs.scipy.org/doc/numpy-1.16.1/reference/generated/numpy.RankWarning.html