numpy.polynomial.polyutils.trimcoef

numpy.polynomial.polyutils.trimcoef(c, tol=0) [source]

Remove “small” “trailing” coefficients from a polynomial.

“Small” means “small in absolute value” and is controlled by the parameter tol; “trailing” means highest order coefficient(s), e.g., in [0, 1, 1, 0, 0] (which represents 0 + x + x**2 + 0*x**3 + 0*x**4) both the 3-rd and 4-th order coefficients would be “trimmed.”

Parameters

carray_like

1-d array of coefficients, ordered from lowest order to highest.

tolnumber, optional

Trailing (i.e., highest order) elements with absolute value less than or equal to tol (default value is zero) are removed.

Returns

trimmedndarray

1-d array with trailing zeros removed. If the resulting series would be empty, a series containing a single zero is returned.

Raises

ValueError

If tol < 0

See also

trimseq

Examples

>>> from numpy.polynomial import polyutils as pu
>>> pu.trimcoef((0,0,3,0,5,0,0))
array([0.,  0.,  3.,  0.,  5.])
>>> pu.trimcoef((0,0,1e-3,0,1e-5,0,0),1e-3) # item == tol is trimmed
array([0.])
>>> i = complex(0,1) # works for complex
>>> pu.trimcoef((3e-4,1e-3*(1-i),5e-4,2e-5*(1+i)), 1e-3)
array([0.0003+0.j   , 0.001 -0.001j])