numpy.polynomial.chebyshev.chebtrim — NumPy v1.15 Manual (original) (raw)
numpy.polynomial.chebyshev. chebtrim(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: | c : array_like 1-d array of coefficients, ordered from lowest order to highest. tol : number, optional Trailing (i.e., highest order) elements with absolute value less than or equal to tol (default value is zero) are removed. |
|---|---|
| Returns: | trimmed : ndarray 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 |
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 , 0.0010-0.001j])