def chunk(self, f, a=-1, b=1, n=31, tol=1e-15):
x = self.chebNodes(a, b, n)
fx = f(x)
cfxl = self.chebTransform(fx)
x = np.linspace(a, b, 10000)
fxl = self.chebEval(cfxl, x, a, b)
# print(cfxl)
# plt.loglog(np.abs(cfxl))
# plt.show()
x = self.chebNodes(a, b, n)
fx = f(g(x))
# nn = np.arange(fx.size)
cfxh = self.chebTransform(fx)
x = np.linspace(a, b, 10000)
fxh = self.chebEval(cfxh, x, a, b)
# plt.plot(x, fxh)
# plt.plot(x, fxl)
# plt.show()
print(int)
cf = np_cheb.chebsub(cfxh, cfxl)
# cdf = self.chebDiff(cfxh, 3)
x = np.linspace(a, b, 10000)
df = self.chebEval(cf, x, a, b)
# plt.loglog(np.abs(cf))
# plt.show()
plt.plot(x, df)
plt.show()
roots = self.chebRoots(cdf, a, b)
sf = self.chebEval(cf, roots, a, b)
dp = roots[np.argmax(np.abs(sf))]
# print('root', dp, 'value', np.max(np.abs(fxh - fxl)))
# plt.plot(x, fxh - fxl)
# plt.show()
return dp, np.max(np.abs(sf))
def test_chebsub(self) :
for i in range(5) :
for j in range(5) :
msg = "At i=%d, j=%d" % (i,j)
tgt = np.zeros(max(i,j) + 1)
tgt[i] += 1
tgt[j] -= 1
res = cheb.chebsub([0]*i + [1], [0]*j + [1])
assert_equal(trim(res), trim(tgt), err_msg=msg)
def test_chebsub(self):
for i in range(5):
for j in range(5):
msg = "At i=%d, j=%d" % (i, j)
tgt = np.zeros(max(i, j) + 1)
tgt[i] += 1
tgt[j] -= 1
res = cheb.chebsub([0]*i + [1], [0]*j + [1])
assert_equal(trim(res), trim(tgt), err_msg=msg)
def chebsub(c1, c2):
from numpy.polynomial.chebyshev import chebsub
return chebsub(c1, c2)
def chebsub(c1, c2):
from numpy.polynomial.chebyshev import chebsub
return chebsub(c1, c2)
