def polysub(c1, c2):
<EOL>[c1, c2] = pu.as_series([c1, c2])<EOL>if len(c1) > len(c2):<EOL><INDENT>c1[:c2.size] -= c2<EOL>ret = c1<EOL><DEDENT>else:<EOL><INDENT>c2 = -c2<EOL>c2[:c1.size] += c1<EOL>ret = c2<EOL><DEDENT>return pu.trimseq(ret)<EOL>
Subtract one polynomial from another.

Returns the difference of two polynomials `c1` - `c2`.  The arguments
are sequences of coefficients from lowest order term to highest, i.e.,
[1,2,3] represents the polynomial ``1 + 2*x + 3*x**2``.

Parameters
----------
c1, c2 : array_like
    1-D arrays of polynomial coefficients ordered from low to
    high.

Returns
-------
out : ndarray
    Of coefficients representing their difference.

See Also
--------
polyadd, polymul, polydiv, polypow

Examples
--------
>>> from numpy.polynomial import polynomial as P
>>> c1 = (1,2,3)
>>> c2 = (3,2,1)
>>> P.polysub(c1,c2)
array([-2.,  0.,  2.])
>>> P.polysub(c2,c1) # -P.polysub(c1,c2)
array([ 2.,  0., -2.])