# Python numpy.poly() 使用实例

The following are code examples for showing how to use . They are extracted from open source Python projects. You can vote up the examples you like or vote down the exmaples you don’t like. You can also save this page to your account.

Example 1

```def estimate_time_constant(y, p=2, sn=None, lags=5, fudge_factor=1.):
"""
Estimate AR model parameters through the autocovariance function

Parameters
----------
y : array, shape (T,)
One dimensional array containing the fluorescence intensities with
one entry per time-bin.
p : positive integer
order of AR system
sn : float
sn standard deviation, estimated if not provided.
lags : positive integer
number of additional lags where he autocovariance is computed
fudge_factor : float (0< fudge_factor <= 1)
shrinkage factor to reduce bias

Returns
-------
g : estimated coefficients of the AR process
"""

if sn is None:
sn = GetSn(y)

lags += p
xc = axcov(y, lags)
xc = xc[:, np.newaxis]

A = scipy.linalg.toeplitz(xc[lags + np.arange(lags)],
xc[lags + np.arange(p)]) - sn**2 * np.eye(lags, p)
g = np.linalg.lstsq(A, xc[lags + 1:])[0]
gr = np.roots(np.concatenate([np.array([1]), -g.flatten()]))
gr = (gr + gr.conjugate()) / 2.
gr[gr > 1] = 0.95 + np.random.normal(0, 0.01, np.sum(gr > 1))
gr[gr < 0] = 0.15 + np.random.normal(0, 0.01, np.sum(gr < 0))
g = np.poly(fudge_factor * gr)
g = -g[1:]

return g.flatten() ```

Example 2

```def test_poly(self):
assert_array_almost_equal(np.poly([3, -np.sqrt(2), np.sqrt(2)]),
[1, -3, -2, 6])

# From matlab docs
A = [[1, 2, 3], [4, 5, 6], [7, 8, 0]]
assert_array_almost_equal(np.poly(A), [1, -6, -72, -27])

# Should produce real output for perfect conjugates
assert_(np.isrealobj(np.poly([+1.082j, +2.613j, -2.613j, -1.082j])))
assert_(np.isrealobj(np.poly([0+1j, -0+-1j, 1+2j,
1-2j, 1.+3.5j, 1-3.5j])))
assert_(np.isrealobj(np.poly([1j, -1j, 1+2j, 1-2j, 1+3j, 1-3.j])))
assert_(np.isrealobj(np.poly([1j, -1j, 1+2j, 1-2j])))
assert_(np.isrealobj(np.poly([1j, -1j, 2j, -2j])))
assert_(np.isrealobj(np.poly([1j, -1j])))
assert_(np.isrealobj(np.poly([1, -1])))

assert_(np.iscomplexobj(np.poly([1j, -1.0000001j])))

np.random.seed(42)
a = np.random.randn(100) + 1j*np.random.randn(100)
assert_(np.isrealobj(np.poly(np.concatenate((a, np.conjugate(a)))))) ```

Example 3

```def test_objects(self):
from decimal import Decimal
p = np.poly1d([Decimal('4.0'), Decimal('3.0'), Decimal('2.0')])
p2 = p * Decimal('1.333333333333333')
assert_(p2[1] == Decimal("3.9999999999999990"))
p2 = p.deriv()
assert_(p2[1] == Decimal('8.0'))
p2 = p.integ()
assert_(p2[3] == Decimal("1.333333333333333333333333333"))
assert_(p2[2] == Decimal('1.5'))
assert_(np.issubdtype(p2.coeffs.dtype, np.object_))
p = np.poly([Decimal(1), Decimal(2)])
assert_equal(np.poly([Decimal(1), Decimal(2)]),
[1, Decimal(-3), Decimal(2)]) ```

Example 4

```def test_zero_dims(self):
try:
np.poly(np.zeros((0, 0)))
except ValueError:
pass ```

Example 5

```def test_poly_int_overflow(self):
"""
Regression test for gh-5096.
"""
v = np.arange(1, 21)
assert_almost_equal(np.poly(v), np.poly(np.diag(v))) ```

Example 6

```def lsf_to_lpc(all_lsf):
if len(all_lsf.shape) < 2:
all_lsf = all_lsf[None]
order = all_lsf.shape[1]
all_lpc = np.zeros((len(all_lsf), order + 1))
for i in range(len(all_lsf)):
lsf = all_lsf[i]
zeros = np.exp(1j * lsf)
sum_zeros = zeros[::2]
diff_zeros = zeros[1::2]
sum_zeros = np.hstack((sum_zeros, np.conj(sum_zeros)))
diff_zeros = np.hstack((diff_zeros, np.conj(diff_zeros)))
sum_filt = np.poly(sum_zeros)
diff_filt = np.poly(diff_zeros)

if order % 2 != 0:
deconv_diff = sg.convolve(diff_filt, [1, 0, -1])
deconv_sum = sum_filt
else:
deconv_diff = sg.convolve(diff_filt, [1, -1])
deconv_sum = sg.convolve(sum_filt, [1, 1])

lpc = .5 * (deconv_sum + deconv_diff)
# Last coefficient is 0 and not returned
all_lpc[i] = lpc[:-1]
return np.squeeze(all_lpc) ```

Example 7

```def lsf_to_lpc(all_lsf):
if len(all_lsf.shape) < 2:
all_lsf = all_lsf[None]
order = all_lsf.shape[1]
all_lpc = np.zeros((len(all_lsf), order + 1))
for i in range(len(all_lsf)):
lsf = all_lsf[i]
zeros = np.exp(1j * lsf)
sum_zeros = zeros[::2]
diff_zeros = zeros[1::2]
sum_zeros = np.hstack((sum_zeros, np.conj(sum_zeros)))
diff_zeros = np.hstack((diff_zeros, np.conj(diff_zeros)))
sum_filt = np.poly(sum_zeros)
diff_filt = np.poly(diff_zeros)

if order % 2 != 0:
deconv_diff = sg.convolve(diff_filt, [1, 0, -1])
deconv_sum = sum_filt
else:
deconv_diff = sg.convolve(diff_filt, [1, -1])
deconv_sum = sg.convolve(sum_filt, [1, 1])

lpc = .5 * (deconv_sum + deconv_diff)
# Last coefficient is 0 and not returned
all_lpc[i] = lpc[:-1]
return np.squeeze(all_lpc) ```

Example 8

```def test_objects(self):
from decimal import Decimal
p = np.poly1d([Decimal('4.0'), Decimal('3.0'), Decimal('2.0')])
p2 = p * Decimal('1.333333333333333')
assert_(p2[1] == Decimal("3.9999999999999990"))
p2 = p.deriv()
assert_(p2[1] == Decimal('8.0'))
p2 = p.integ()
assert_(p2[3] == Decimal("1.333333333333333333333333333"))
assert_(p2[2] == Decimal('1.5'))
assert_(np.issubdtype(p2.coeffs.dtype, np.object_))
p = np.poly([Decimal(1), Decimal(2)])
assert_equal(np.poly([Decimal(1), Decimal(2)]),
[1, Decimal(-3), Decimal(2)]) ```

Example 9

```def test_zero_dims(self):
try:
np.poly(np.zeros((0, 0)))
except ValueError:
pass ```

Example 10

```def test_poly_int_overflow(self):
"""
Regression test for gh-5096.
"""
v = np.arange(1, 21)
assert_almost_equal(np.poly(v), np.poly(np.diag(v))) ```

Example 11

```def estimate_time_constant(fluor, p = 2, sn = None, lags = 5, fudge_factor = 1.):
"""
Estimate AR model parameters through the autocovariance function
Inputs
----------
fluor        : nparray
One dimensional array containing the fluorescence intensities with
one entry per time-bin.
p            : positive integer
order of AR system
sn           : float
noise standard deviation, estimated if not provided.
lags         : positive integer
number of additional lags where he autocovariance is computed
fudge_factor : float (0< fudge_factor <= 1)
shrinkage factor to reduce bias

Return
-----------
g       : estimated coefficients of the AR process
"""

if sn is None:
sn = GetSn(fluor)

lags += p
xc = axcov(fluor,lags)
xc = xc[:,np.newaxis]

A = scipy.linalg.toeplitz(xc[lags+np.arange(lags)],xc[lags+np.arange(p)]) - sn**2*np.eye(lags,p)
g = np.linalg.lstsq(A,xc[lags+1:])[0]
gr = np.roots(np.concatenate([np.array([1]),-g.flatten()]))
gr = (gr+gr.conjugate())/2.
gr[gr>1] = 0.95 + np.random.normal(0,0.01,np.sum(gr>1))
gr[gr<0] = 0.15 + np.random.normal(0,0.01,np.sum(gr<0))
g = np.poly(fudge_factor*gr)
g = -g[1:]

return g.flatten() ```

Example 12

```def test_objects(self):
from decimal import Decimal
p = np.poly1d([Decimal('4.0'), Decimal('3.0'), Decimal('2.0')])
p2 = p * Decimal('1.333333333333333')
assert_(p2[1] == Decimal("3.9999999999999990"))
p2 = p.deriv()
assert_(p2[1] == Decimal('8.0'))
p2 = p.integ()
assert_(p2[3] == Decimal("1.333333333333333333333333333"))
assert_(p2[2] == Decimal('1.5'))
assert_(np.issubdtype(p2.coeffs.dtype, np.object_))
p = np.poly([Decimal(1), Decimal(2)])
assert_equal(np.poly([Decimal(1), Decimal(2)]),
[1, Decimal(-3), Decimal(2)]) ```

Example 13

```def test_zero_dims(self):
try:
np.poly(np.zeros((0, 0)))
except ValueError:
pass ```

Example 14

```def test_poly_int_overflow(self):
"""
Regression test for gh-5096.
"""
v = np.arange(1, 21)
assert_almost_equal(np.poly(v), np.poly(np.diag(v))) ```

Example 15

```def z_coeff(Poles,Zeros,fs,g,fg,fo = 'none'):
if fg == np.inf:
fg = fs/2
if fo == 'none':
beta = 1.0
else:
beta = f_warp(fo,fs)/fo
a = np.poly(z_from_f(beta*np.array(Poles),fs))
b = np.poly(z_from_f(beta*np.array(Zeros),fs))
gain = 10.**(g/20.)/abs(Fz_at_f(beta*np.array(Poles),beta*np.array(Zeros),fg,fs))

return (a,b*gain) ```

Example 16

```def test_objects(self):
from decimal import Decimal
p = np.poly1d([Decimal('4.0'), Decimal('3.0'), Decimal('2.0')])
p2 = p * Decimal('1.333333333333333')
assert_(p2[1] == Decimal("3.9999999999999990"))
p2 = p.deriv()
assert_(p2[1] == Decimal('8.0'))
p2 = p.integ()
assert_(p2[3] == Decimal("1.333333333333333333333333333"))
assert_(p2[2] == Decimal('1.5'))
assert_(np.issubdtype(p2.coeffs.dtype, np.object_))
p = np.poly([Decimal(1), Decimal(2)])
assert_equal(np.poly([Decimal(1), Decimal(2)]),
[1, Decimal(-3), Decimal(2)]) ```

Example 17

```def test_zero_dims(self):
try:
np.poly(np.zeros((0, 0)))
except ValueError:
pass ```

Example 18

```def test_poly_int_overflow(self):
"""
Regression test for gh-5096.
"""
v = np.arange(1, 21)
assert_almost_equal(np.poly(v), np.poly(np.diag(v))) ```

Example 19

```def test_objects(self):
from decimal import Decimal
p = np.poly1d([Decimal('4.0'), Decimal('3.0'), Decimal('2.0')])
p2 = p * Decimal('1.333333333333333')
assert_(p2[1] == Decimal("3.9999999999999990"))
p2 = p.deriv()
assert_(p2[1] == Decimal('8.0'))
p2 = p.integ()
assert_(p2[3] == Decimal("1.333333333333333333333333333"))
assert_(p2[2] == Decimal('1.5'))
assert_(np.issubdtype(p2.coeffs.dtype, np.object_))
p = np.poly([Decimal(1), Decimal(2)])
assert_equal(np.poly([Decimal(1), Decimal(2)]),
[1, Decimal(-3), Decimal(2)]) ```

Example 20

```def test_zero_dims(self):
try:
np.poly(np.zeros((0, 0)))
except ValueError:
pass ```

Example 21

```def test_poly_int_overflow(self):
"""
Regression test for gh-5096.
"""
v = np.arange(1, 21)
assert_almost_equal(np.poly(v), np.poly(np.diag(v))) ```

Example 22

```def lsf_to_lpc(all_lsf):
if len(all_lsf.shape) < 2:
all_lsf = all_lsf[None]
order = all_lsf.shape[1]
all_lpc = np.zeros((len(all_lsf), order + 1))
for i in range(len(all_lsf)):
lsf = all_lsf[i]
zeros = np.exp(1j * lsf)
sum_zeros = zeros[::2]
diff_zeros = zeros[1::2]
sum_zeros = np.hstack((sum_zeros, np.conj(sum_zeros)))
diff_zeros = np.hstack((diff_zeros, np.conj(diff_zeros)))
sum_filt = np.poly(sum_zeros)
diff_filt = np.poly(diff_zeros)

if order % 2 != 0:
deconv_diff = sg.convolve(diff_filt, [1, 0, -1])
deconv_sum = sum_filt
else:
deconv_diff = sg.convolve(diff_filt, [1, -1])
deconv_sum = sg.convolve(sum_filt, [1, 1])

lpc = .5 * (deconv_sum + deconv_diff)
# Last coefficient is 0 and not returned
all_lpc[i] = lpc[:-1]
return np.squeeze(all_lpc) ```

Example 23

```def lsf_to_lpc(all_lsf):
if len(all_lsf.shape) < 2:
all_lsf = all_lsf[None]
order = all_lsf.shape[1]
all_lpc = np.zeros((len(all_lsf), order + 1))
for i in range(len(all_lsf)):
lsf = all_lsf[i]
zeros = np.exp(1j * lsf)
sum_zeros = zeros[::2]
diff_zeros = zeros[1::2]
sum_zeros = np.hstack((sum_zeros, np.conj(sum_zeros)))
diff_zeros = np.hstack((diff_zeros, np.conj(diff_zeros)))
sum_filt = np.poly(sum_zeros)
diff_filt = np.poly(diff_zeros)

if order % 2 != 0:
deconv_diff = sg.convolve(diff_filt, [1, 0, -1])
deconv_sum = sum_filt
else:
deconv_diff = sg.convolve(diff_filt, [1, -1])
deconv_sum = sg.convolve(sum_filt, [1, 1])

lpc = .5 * (deconv_sum + deconv_diff)
# Last coefficient is 0 and not returned
all_lpc[i] = lpc[:-1]
return np.squeeze(all_lpc) ```

Example 24

```def lsf_to_lpc(all_lsf):
if len(all_lsf.shape) < 2:
all_lsf = all_lsf[None]
order = all_lsf.shape[1]
all_lpc = np.zeros((len(all_lsf), order + 1))
for i in range(len(all_lsf)):
lsf = all_lsf[i]
zeros = np.exp(1j * lsf)
sum_zeros = zeros[::2]
diff_zeros = zeros[1::2]
sum_zeros = np.hstack((sum_zeros, np.conj(sum_zeros)))
diff_zeros = np.hstack((diff_zeros, np.conj(diff_zeros)))
sum_filt = np.poly(sum_zeros)
diff_filt = np.poly(diff_zeros)

if order % 2 != 0:
deconv_diff = sg.convolve(diff_filt, [1, 0, -1])
deconv_sum = sum_filt
else:
deconv_diff = sg.convolve(diff_filt, [1, -1])
deconv_sum = sg.convolve(sum_filt, [1, 1])

lpc = .5 * (deconv_sum + deconv_diff)
# Last coefficient is 0 and not returned
all_lpc[i] = lpc[:-1]
return np.squeeze(all_lpc) ```

Example 25

```def lsf_to_lpc(all_lsf):
if len(all_lsf.shape) < 2:
all_lsf = all_lsf[None]
order = all_lsf.shape[1]
all_lpc = np.zeros((len(all_lsf), order + 1))
for i in range(len(all_lsf)):
lsf = all_lsf[i]
zeros = np.exp(1j * lsf)
sum_zeros = zeros[::2]
diff_zeros = zeros[1::2]
sum_zeros = np.hstack((sum_zeros, np.conj(sum_zeros)))
diff_zeros = np.hstack((diff_zeros, np.conj(diff_zeros)))
sum_filt = np.poly(sum_zeros)
diff_filt = np.poly(diff_zeros)

if order % 2 != 0:
deconv_diff = sg.convolve(diff_filt, [1, 0, -1])
deconv_sum = sum_filt
else:
deconv_diff = sg.convolve(diff_filt, [1, -1])
deconv_sum = sg.convolve(sum_filt, [1, 1])

lpc = .5 * (deconv_sum + deconv_diff)
# Last coefficient is 0 and not returned
all_lpc[i] = lpc[:-1]
return np.squeeze(all_lpc) ```

Example 26

```def lsf_to_lpc(all_lsf):
if len(all_lsf.shape) < 2:
all_lsf = all_lsf[None]
order = all_lsf.shape[1]
all_lpc = np.zeros((len(all_lsf), order + 1))
for i in range(len(all_lsf)):
lsf = all_lsf[i]
zeros = np.exp(1j * lsf)
sum_zeros = zeros[::2]
diff_zeros = zeros[1::2]
sum_zeros = np.hstack((sum_zeros, np.conj(sum_zeros)))
diff_zeros = np.hstack((diff_zeros, np.conj(diff_zeros)))
sum_filt = np.poly(sum_zeros)
diff_filt = np.poly(diff_zeros)

if order % 2 != 0:
deconv_diff = sg.convolve(diff_filt, [1, 0, -1])
deconv_sum = sum_filt
else:
deconv_diff = sg.convolve(diff_filt, [1, -1])
deconv_sum = sg.convolve(sum_filt, [1, 1])

lpc = .5 * (deconv_sum + deconv_diff)
# Last coefficient is 0 and not returned
all_lpc[i] = lpc[:-1]
return np.squeeze(all_lpc) ```

Example 27

```def lsf_to_lpc(all_lsf):
if len(all_lsf.shape) < 2:
all_lsf = all_lsf[None]
order = all_lsf.shape[1]
all_lpc = np.zeros((len(all_lsf), order + 1))
for i in range(len(all_lsf)):
lsf = all_lsf[i]
zeros = np.exp(1j * lsf)
sum_zeros = zeros[::2]
diff_zeros = zeros[1::2]
sum_zeros = np.hstack((sum_zeros, np.conj(sum_zeros)))
diff_zeros = np.hstack((diff_zeros, np.conj(diff_zeros)))
sum_filt = np.poly(sum_zeros)
diff_filt = np.poly(diff_zeros)

if order % 2 != 0:
deconv_diff = sg.convolve(diff_filt, [1, 0, -1])
deconv_sum = sum_filt
else:
deconv_diff = sg.convolve(diff_filt, [1, -1])
deconv_sum = sg.convolve(sum_filt, [1, 1])

lpc = .5 * (deconv_sum + deconv_diff)
# Last coefficient is 0 and not returned
all_lpc[i] = lpc[:-1]
return np.squeeze(all_lpc) ```

Example 28

```def lsf_to_lpc(all_lsf):
if len(all_lsf.shape) < 2:
all_lsf = all_lsf[None]
order = all_lsf.shape[1]
all_lpc = np.zeros((len(all_lsf), order + 1))
for i in range(len(all_lsf)):
lsf = all_lsf[i]
zeros = np.exp(1j * lsf)
sum_zeros = zeros[::2]
diff_zeros = zeros[1::2]
sum_zeros = np.hstack((sum_zeros, np.conj(sum_zeros)))
diff_zeros = np.hstack((diff_zeros, np.conj(diff_zeros)))
sum_filt = np.poly(sum_zeros)
diff_filt = np.poly(diff_zeros)

if order % 2 != 0:
deconv_diff = sg.convolve(diff_filt, [1, 0, -1])
deconv_sum = sum_filt
else:
deconv_diff = sg.convolve(diff_filt, [1, -1])
deconv_sum = sg.convolve(sum_filt, [1, 1])

lpc = .5 * (deconv_sum + deconv_diff)
# Last coefficient is 0 and not returned
all_lpc[i] = lpc[:-1]
return np.squeeze(all_lpc) ```

Example 29

```def lsf_to_lpc(all_lsf):
if len(all_lsf.shape) < 2:
all_lsf = all_lsf[None]
order = all_lsf.shape[1]
all_lpc = np.zeros((len(all_lsf), order + 1))
for i in range(len(all_lsf)):
lsf = all_lsf[i]
zeros = np.exp(1j * lsf)
sum_zeros = zeros[::2]
diff_zeros = zeros[1::2]
sum_zeros = np.hstack((sum_zeros, np.conj(sum_zeros)))
diff_zeros = np.hstack((diff_zeros, np.conj(diff_zeros)))
sum_filt = np.poly(sum_zeros)
diff_filt = np.poly(diff_zeros)

if order % 2 != 0:
deconv_diff = sg.convolve(diff_filt, [1, 0, -1])
deconv_sum = sum_filt
else:
deconv_diff = sg.convolve(diff_filt, [1, -1])
deconv_sum = sg.convolve(sum_filt, [1, 1])

lpc = .5 * (deconv_sum + deconv_diff)
# Last coefficient is 0 and not returned
all_lpc[i] = lpc[:-1]
return np.squeeze(all_lpc) ```

Example 30

```def lsf_to_lpc(all_lsf):
if len(all_lsf.shape) < 2:
all_lsf = all_lsf[None]
order = all_lsf.shape[1]
all_lpc = np.zeros((len(all_lsf), order + 1))
for i in range(len(all_lsf)):
lsf = all_lsf[i]
zeros = np.exp(1j * lsf)
sum_zeros = zeros[::2]
diff_zeros = zeros[1::2]
sum_zeros = np.hstack((sum_zeros, np.conj(sum_zeros)))
diff_zeros = np.hstack((diff_zeros, np.conj(diff_zeros)))
sum_filt = np.poly(sum_zeros)
diff_filt = np.poly(diff_zeros)

if order % 2 != 0:
deconv_diff = sg.convolve(diff_filt, [1, 0, -1])
deconv_sum = sum_filt
else:
deconv_diff = sg.convolve(diff_filt, [1, -1])
deconv_sum = sg.convolve(sum_filt, [1, 1])

lpc = .5 * (deconv_sum + deconv_diff)
# Last coefficient is 0 and not returned
all_lpc[i] = lpc[:-1]
return np.squeeze(all_lpc) ```

Example 31

```def lsf_to_lpc(all_lsf):
if len(all_lsf.shape) < 2:
all_lsf = all_lsf[None]
order = all_lsf.shape[1]
all_lpc = np.zeros((len(all_lsf), order + 1))
for i in range(len(all_lsf)):
lsf = all_lsf[i]
zeros = np.exp(1j * lsf)
sum_zeros = zeros[::2]
diff_zeros = zeros[1::2]
sum_zeros = np.hstack((sum_zeros, np.conj(sum_zeros)))
diff_zeros = np.hstack((diff_zeros, np.conj(diff_zeros)))
sum_filt = np.poly(sum_zeros)
diff_filt = np.poly(diff_zeros)

if order % 2 != 0:
deconv_diff = sg.convolve(diff_filt, [1, 0, -1])
deconv_sum = sum_filt
else:
deconv_diff = sg.convolve(diff_filt, [1, -1])
deconv_sum = sg.convolve(sum_filt, [1, 1])

lpc = .5 * (deconv_sum + deconv_diff)
# Last coefficient is 0 and not returned
all_lpc[i] = lpc[:-1]
return np.squeeze(all_lpc) ```

Example 32

```def lsf_to_lpc(all_lsf):
if len(all_lsf.shape) < 2:
all_lsf = all_lsf[None]
order = all_lsf.shape[1]
all_lpc = np.zeros((len(all_lsf), order + 1))
for i in range(len(all_lsf)):
lsf = all_lsf[i]
zeros = np.exp(1j * lsf)
sum_zeros = zeros[::2]
diff_zeros = zeros[1::2]
sum_zeros = np.hstack((sum_zeros, np.conj(sum_zeros)))
diff_zeros = np.hstack((diff_zeros, np.conj(diff_zeros)))
sum_filt = np.poly(sum_zeros)
diff_filt = np.poly(diff_zeros)

if order % 2 != 0:
deconv_diff = sg.convolve(diff_filt, [1, 0, -1])
deconv_sum = sum_filt
else:
deconv_diff = sg.convolve(diff_filt, [1, -1])
deconv_sum = sg.convolve(sum_filt, [1, 1])

lpc = .5 * (deconv_sum + deconv_diff)
# Last coefficient is 0 and not returned
all_lpc[i] = lpc[:-1]
return np.squeeze(all_lpc) ```

Example 33

```def test_objects(self):
from decimal import Decimal
p = np.poly1d([Decimal('4.0'), Decimal('3.0'), Decimal('2.0')])
p2 = p * Decimal('1.333333333333333')
assert_(p2[1] == Decimal("3.9999999999999990"))
p2 = p.deriv()
assert_(p2[1] == Decimal('8.0'))
p2 = p.integ()
assert_(p2[3] == Decimal("1.333333333333333333333333333"))
assert_(p2[2] == Decimal('1.5'))
assert_(np.issubdtype(p2.coeffs.dtype, np.object_))
p = np.poly([Decimal(1), Decimal(2)])
assert_equal(np.poly([Decimal(1), Decimal(2)]),
[1, Decimal(-3), Decimal(2)]) ```

Example 34

```def test_zero_dims(self):
try:
np.poly(np.zeros((0, 0)))
except ValueError:
pass ```

Example 35

```def test_poly_int_overflow(self):
"""
Regression test for gh-5096.
"""
v = np.arange(1, 21)
assert_almost_equal(np.poly(v), np.poly(np.diag(v))) ```