def invert_legendre_polynomial(wavemin,
wavemax,
ycoef,
xcoef,
sigmacoef,
fiber,
npix_y,
wave_of_y,
width=7):
# Wavelength array used in 'invert_legendre_polynomial'
wave = np.linspace(wavemin, wavemax, 100)
# Determines value of Y, so we can know its coeficient and then its position
y_of_wave = legval(u(wave, wavemin, wavemax), ycoef[fiber])
coef = legfit(u(y_of_wave, 0, npix_y), wave, deg=ycoef[fiber].size)
wave_of_y[fiber] = legval(u(np.arange(npix_y).astype(float), 0, npix_y),
coef)
# Determines wavelength intensity (x) based on Y
x_of_y = legval(u(wave_of_y[fiber], wavemin, wavemax), xcoef[fiber])
sigma_of_y = legval(u(wave_of_y[fiber], wavemin, wavemax),
sigmacoef[fiber])
# Ascertain X by using low and high uncertainty
x1_of_y = np.floor(x_of_y).astype(int) - width / 2
x2_of_y = np.floor(x_of_y).astype(int) + width / 2 + 2
return (x1_of_y, x_of_y, x2_of_y, sigma_of_y)
def leggauss(n, x0=None):
"""
Abscissa and weights for Gauss-Legendre quadrature.
Parameters
----------
n : int
Returns
-------
x : ndarray
weights : ndarray
"""
J = legjacobi(n)
if x0 is None:
x, vec = np.linalg.eigh(J)
return x, vec[0]**2 * 2
else:
from numpy.polynomial.legendre import legval
J[-1,
-1] = x0 - J[-1, -2]**2 * legval(x0, [0] * (n - 2) + [1]) / legval(
x0, [0] * (n - 1) + [1])
x, vec = np.linalg.eigh(J)
return x, vec[0]**2 * 2
def hamiltonian_matrix(BASIS_SIZE=BASIS_SIZE,
BASIS_FUNC=BASIS_FUNC,
DOMAIN=DOMAIN,
C=C,
V=V):
'''Calculates the hamiltonian matrix <psi|H|psi>'''
if BASIS_FUNC == 'legendre':
hmat = np.zeros((BASIS_SIZE, BASIS_SIZE))
for i in range(BASIS_SIZE):
for j in range(BASIS_SIZE):
coefs_i = [0] * (i) + [1]
coefs_j = [0] * (j) + [1]
inside = L.legmul(coefs_i, list(hamiltonian(coefs_j)))
integ = L.legint(inside)
val = L.legval(DOMAIN[1], integ) - L.legval(DOMAIN[0], integ)
hmat[i, j] = val
if BASIS_FUNC == 'fourier':
a = DOMAIN[
1] #restrict the domain to be symmetric about origin for simplicity
hmat = np.zeros((BASIS_SIZE, BASIS_SIZE))
for i in range(BASIS_SIZE):
for j in range(BASIS_SIZE):
p1 = 2 * V * np.sin(a * j) / j #cos V0 term
p2 = 0 #cos cos term cancels due to parity if i != j
if i == j:
p2 = C * (j**2) * (a + np.sin(2 * a * j) / (2 * j))
hmat[i, j] = p1 + p2
return hmat
def evaluate_basis_gauss(self):
"""Evaluate the basis at the Gaussian quadrature nodes.
phi will be used to transform Legendre solution coefficients
to the solution evaluated at the Gaussian quadrature nodes.
dphi_w will be used for the interior flux integral
"""
phi = np.zeros((len(self.x), self.N_s))
dphi_w = np.zeros((len(self.x), self.N_s))
for n in range(self.N_s):
# Get the Legendre polynomial of order n and its gradient
l = L.basis(n)
dl = l.deriv()
# Evaluate the basis at the Gaussian nodes
phi[:, n] = leg.legval(self.x, l.coef)
# Evaluate the gradient at the Gaussian nodes and multiply by the
# weights
dphi_w[n, :] = leg.legval(self.x, dl.coef) * self.w
return phi, dphi_w
def evaluate_basis_gauss(self):
"""Evaluate the basis at the Gaussian quadrature nodes.
phi will be used to transform Legendre solution coefficients
to the solution evaluated at the Gaussian quadrature nodes.
dphi_w will be used for the interior flux integral
"""
phi = np.zeros((len(self.x), self.N_s))
dphi_w = np.zeros((len(self.x), self.N_s))
for n in range(self.N_s):
# Get the Legendre polynomial of order n and its gradient
l = L.basis(n)
dl = l.deriv()
# Evaluate the basis at the Gaussian nodes
phi[:, n] = leg.legval(self.x, l.coef)
# Evaluate the gradient at the Gaussian nodes and multiply by the
# weights
dphi_w[n, :] = leg.legval(self.x, dl.coef) * self.w
return phi, dphi_w
def fitcont(wave, flux, sigup, fitidx, maxorder=6):
wavepts = wave[fitidx]
fluxpts = flux[fitidx]
sigpts = sigup[fitidx]
### Cycle through fits of several orders and decide the appropriate order by F-test
coeffs = []
covmtxs = []
fits = []
chisqs = []
dfs = []
fprob = 0.
i = 0
order = 1
while (fprob <= 0.95) & (order <= maxorder):
order = i + 1
coeff, covmtx = fitlegendre(wavepts, fluxpts, sigpts, order)
coeffs.append(coeff)
covmtxs.append(covmtx)
fit = L.legval(wavepts, coeff, order)
fits.append(fit)
chisq, df = redchisq(fluxpts, fit, sigpts, order)
chisqs.append(chisq), dfs.append(df)
if i > 0:
fval = chisqs[i] / chisqs[i - 1]
fprob = stats.f.cdf(fval, dfs[i], dfs[i - 1])
i += 1
### Choose fit of order just prior to where F-test indicates no improvement
fitcoeff = coeffs[i - 2]
fitcovmtx = covmtxs[i - 2]
wrange = range(fitidx[0], fitidx[-1])
cont = L.legval(wave[wrange], fitcoeff)
return fitcoeff, fitcovmtx
def term_ijk(self, index):
i, j, k = index
ci = np.zeros(i + 1)
cj = np.zeros(j + 1)
ck = np.zeros(k + 1)
ci[-1] = cj[-1] = ck[-1] = 1
return legval(self.r[0], ci) * legval(self.r[1], cj) * legval(
self.r[2], ck)
def genericLegVal(locations, coeffs):
if len(locations.shape)==1:
return leg.legval(locations,coeffs)
else: # assume dim 0 is points, dim 1 is dimensions
c=leg.legval(locations[:,0], coeffs)
for i in range(1, locations.shape[1]):
c=leg.legval(locations[:,i],c, tensor=False)
return c
def gaussian_latitudes(n):
"""Construct latitudes and latitude bounds for a Gaussian grid.
Args:
* n:
The Gaussian grid number (half the number of latitudes in the
grid.
Returns:
A 2-tuple where the first element is a length `n` array of
latitudes (in degrees) and the second element is an `(n, 2)`
array of bounds.
"""
if abs(int(n)) != n:
raise ValueError('n must be a non-negative integer')
nlat = 2 * n
# Create the coefficients of the Legendre polynomial and construct the
# companion matrix:
cs = np.array([0] * nlat + [1], dtype=np.int)
cm = legcompanion(cs)
# Compute the eigenvalues of the companion matrix (the roots of the
# Legendre polynomial) taking advantage of the fact that the matrix is
# symmetric:
roots = la.eigvalsh(cm)
roots.sort()
# Improve the roots by one application of Newton's method, using the
# solved root as the initial guess:
fx = legval(roots, cs)
fpx = legval(roots, legder(cs))
roots -= fx / fpx
# The roots should exhibit symmetry, but with a sign change, so make sure
# this is the case:
roots = (roots - roots[::-1]) / 2.
# Compute the Gaussian weights for each interval:
fm = legval(roots, cs[1:])
fm /= np.abs(fm).max()
fpx /= np.abs(fpx).max()
weights = 1. / (fm * fpx)
# Weights should be symmetric and sum to two (unit weighting over the
# interval [-1, 1]):
weights = (weights + weights[::-1]) / 2.
weights *= 2. / weights.sum()
# Calculate the bounds from the weights, still on the interval [-1, 1]:
bounds1d = np.empty([nlat + 1])
bounds1d[0] = -1
bounds1d[1:-1] = -1 + weights[:-1].cumsum()
bounds1d[-1] = 1
# Convert the bounds to degrees of latitude on [-90, 90]:
bounds1d = np.rad2deg(np.arcsin(bounds1d))
bounds2d = np.empty([nlat, 2])
bounds2d[:, 0] = bounds1d[:-1]
bounds2d[:, 1] = bounds1d[1:]
# Convert the roots from the interval [-1, 1] to latitude values on the
# interval [-90, 90] degrees:
latitudes = np.rad2deg(np.arcsin(roots))
return latitudes, bounds2d
def gaussian_latitudes(n):
"""Construct latitudes and latitude bounds for a Gaussian grid.
Args:
* n:
The Gaussian grid number (half the number of latitudes in the
grid.
Returns:
A 2-tuple where the first element is a length `n` array of
latitudes (in degrees) and the second element is an `(n, 2)`
array of bounds.
"""
if abs(int(n)) != n:
raise ValueError('n must be a non-negative integer')
nlat = 2 * n
# Create the coefficients of the Legendre polynomial and construct the
# companion matrix:
cs = np.array([0] * nlat + [1], dtype=np.int)
cm = legcompanion(cs)
# Compute the eigenvalues of the companion matrix (the roots of the
# Legendre polynomial) taking advantage of the fact that the matrix is
# symmetric:
roots = la.eigvalsh(cm)
roots.sort()
# Improve the roots by one application of Newton's method, using the
# solved root as the initial guess:
fx = legval(roots, cs)
fpx = legval(roots, legder(cs))
roots -= fx / fpx
# The roots should exhibit symmetry, but with a sign change, so make sure
# this is the case:
roots = (roots - roots[::-1]) / 2.
# Compute the Gaussian weights for each interval:
fm = legval(roots, cs[1:])
fm /= np.abs(fm).max()
fpx /= np.abs(fpx).max()
weights = 1. / (fm * fpx)
# Weights should be symmetric and sum to two (unit weighting over the
# interval [-1, 1]):
weights = (weights + weights[::-1]) / 2.
weights *= 2. / weights.sum()
# Calculate the bounds from the weights, still on the interval [-1, 1]:
bounds1d = np.empty([nlat + 1])
bounds1d[0] = -1
bounds1d[1:-1] = -1 + weights[:-1].cumsum()
bounds1d[-1] = 1
# Convert the bounds to degrees of latitude on [-90, 90]:
bounds1d = np.rad2deg(np.arcsin(bounds1d))
bounds2d = np.empty([nlat, 2])
bounds2d[:, 0] = bounds1d[:-1]
bounds2d[:, 1] = bounds1d[1:]
# Convert the roots from the interval [-1, 1] to latitude values on the
# interval [-90, 90] degrees:
latitudes = np.rad2deg(np.arcsin(roots))
return latitudes, bounds2d
def eval(self, x, u, output_array=None):
if output_array is None:
output_array = np.zeros(x.shape)
x = self.map_reference_domain(x)
w_hat = work[(u, 0, True)]
self.set_factor_array(u)
output_array[:] = leg.legval(x, u[:-2])
w_hat[2:] = self._factor * u[:-2]
output_array -= leg.legval(x, w_hat)
return output_array
def parallels_transitions(turbine,
joints_parallel,
joints_vel_parallel,
joints_acc_parallel,
times_parallel,
step=.1,
number_of_points=8.):
""" Given all parallels solutions, i.e., joints solutions for all waypoints split in parallels (lists),
this method computes cubic polynomials to interpolate the two points: end of a parallel - begin of the next
parallel, in joint space, considering velocities. It will return the parallels and the computed transition
paths between them.
Obs.: This is taking too long. No improvements are being made since plates can be used on the transition part.
Args:
turbine: (@ref Turbine) turbine object
joints_parallel: (float[m][n<SUB>i</SUB>][nDOF]) list of joints for all parallels
times_parallel: (float[m][n<SUB>i</SUB>]) list of deltatimes for all parallels
step: distance (meters) between points
number_of_points: minimal number of points
max_acc: maximum permitted acceleration (percentage)
Returns:
Modifies the current joints_parallel and times_parallel with the computed transitions.
"""
robot = turbine.robot
for i in range(len(joints_parallel) - 1):
joint_0 = joints_parallel[2 * i][-1]
vel_0 = joints_vel_parallel[2 * i][-1]
joint_1 = joints_parallel[2 * i + 1][0]
vel_1 = joints_vel_parallel[2 * i + 1][0]
c = mathtools.legn_path(3, [joint_0, joint_1], [vel_0, vel_1])
joints = []
joints_vel = []
joints_acc = []
times = []
dt = min([step, 1. / number_of_points])
for t in linspace(0, 1., max([1. / step, number_of_points])):
joints.append(legendre.legval(t, c))
joints_vel.append(legendre.legval(t, legendre.legder(c, 1)))
joints_acc.append(legendre.legval(t, legendre.legder(c, 2)))
times.append(dt)
joints = joints[1:-1]
joints_vel = joints_vel[1:-1]
joints_acc = joints_acc[1:-1]
times_parallel[2 * i + 1][0] = times[-1]
times = times[1:-1]
joints_parallel.insert(2 * i + 1, joints)
joints_vel_parallel.insert(2 * i + 1, joints_vel)
joints_acc_parallel.insert(2 * i + 1, joints_acc)
times_parallel.insert(2 * i + 1, times)
return joints_parallel, joints_vel_parallel, joints_acc_parallel, times_parallel
def eval(self, ispec, x):
xx = self._xnorm(x)
if isinstance(ispec, int):
return legval(xx, self._coeff[ispec])
else:
if ispec is None:
ispec = range(self._coeff.shape[0])
y = [legval(xx, self._coeff[i]) for i in ispec]
return np.array(y)
def inner_product(): #do I even need this?
if BASIS_FUNC == 'legendre':
pmat = np.zeros((BASIS_SIZE, BASIS_SIZE))
for i in range(BASIS_SIZE):
for j in range(BASIS_SIZE):
coefs_i = [0] * (i) + [1]
coefs_j = [0] * (j) + [1]
inside = L.legmul(coefs_i, coefs_j)
integ = L.legint(inside)
val = L.legval(DOMAIN[1], integ) - L.legval(DOMAIN[0], integ)
pmat[i, j] = val
def eval(self, x, u, output_array=None):
if output_array is None:
output_array = np.zeros(x.shape)
x = self.map_reference_domain(x)
w_hat = work[(u, 0, True)]
self.set_factor_array(u)
output_array[:] = leg.legval(x, u[:-2]*self._factor)
w_hat[2:] = u[:-2]*self._factor
output_array -= leg.legval(x, w_hat)
output_array += 0.5*(u[-1]*(1-x)+u[-2]*(1+x))
return output_array
def term_ijk(self, index):
if len(index) == 2:
i, j = index
ci = np.diag(np.ones(i + 1))[i]
cj = np.diag(np.ones(j + 1))[j]
return legval(self.r[2], ci) * legval(self.r[1], cj)
elif len(index) == 1:
k = index[0]
ck = np.diag(np.ones(k + 1))[k]
return legval(self.r[0], ck)
def diffxsec_legendre_eval(sig, mu, coeff):
c = coeff.T
ans = np.zeros_like(mu)
if (len(mu.shape) == 1):
ans = sig * legval(mu, c, tensor=False)
elif (len(mu.shape) == 2):
ans = sig * legval(mu, c[:, None, :], tensor=False)
elif (len(mu.shape) == 3):
ans = sig * legval(mu, c[:, None, None, :], tensor=False)
ans[np.abs(mu) > 1.0] = 0.0
return ans
def eval(self, ispec, x):
xx = self._xnorm(x)
if isinstance(ispec, numbers.Integral):
return legval(xx, self._coeff[ispec])
else:
if ispec is None:
ispec = list(range(self._coeff.shape[0]))
y = [legval(xx, self._coeff[i]) for i in ispec]
return np.array(y)
def weights_roots(order, rules='Gauss-Lobatto'):
c_leg = [1] if order == 0 else [i//order for i in xrange(order+1)]
c_dleg = lgd.legder(c_leg)
if rules == 'Gauss-Lobatto':
xs = np.array( [-1] + list( lgd.legroots(c_dleg) ) + [1] )
ws = 2 / ( order * (order + 1) * (lgd.legval(xs, c_leg)**2) )
elif rules == 'Gauss-Legendre':
xs = lgd.legroots(c_leg)
ws = 2 / ( (1 - xs**2) * (lgd.legval(xs, c_dleg)**2) )
return xs, ws
def test_legmul(self) :
# check values of result
for i in range(5) :
pol1 = [0]*i + [1]
val1 = leg.legval(self.x, pol1)
for j in range(5) :
msg = "At i=%d, j=%d" % (i,j)
pol2 = [0]*j + [1]
val2 = leg.legval(self.x, pol2)
pol3 = leg.legmul(pol1, pol2)
val3 = leg.legval(self.x, pol3)
assert_(len(pol3) == i + j + 1, msg)
assert_almost_equal(val3, val1*val2, err_msg=msg)
def eval(self, x, fk, output_array=None):
if output_array is None:
output_array = np.zeros(x.shape)
x = self.map_reference_domain(x)
w_hat = work[(fk, 0)]
self.set_factor_arrays(fk)
output_array[:] = leg.legval(x, fk[:-4])
w_hat[2:-2] = self._factor1 * fk[:-4]
output_array += leg.legval(x, w_hat[:-2])
w_hat[4:] = self._factor2 * fk[:-4]
w_hat[:4] = 0
output_array += leg.legval(x, w_hat)
return output_array
def test_legmul(self) :
# check values of result
for i in range(5) :
pol1 = [0]*i + [1]
val1 = leg.legval(self.x, pol1)
for j in range(5) :
msg = "At i=%d, j=%d" % (i, j)
pol2 = [0]*j + [1]
val2 = leg.legval(self.x, pol2)
pol3 = leg.legmul(pol1, pol2)
val3 = leg.legval(self.x, pol3)
assert_(len(pol3) == i + j + 1, msg)
assert_almost_equal(val3, val1*val2, err_msg=msg)
def invert_legendre_polynomial(wavemin, wavemax, ycoef, xcoef, fiber, npix_y, wave_of_y) :
# Wavelength array used in 'invert_legendre_polynomial'
wave = np.linspace(wavemin, wavemax, 100)
# Determines value of Y, so we can know its coeficient and then its position
y_of_wave = legval(u(wave, wavemin, wavemax), ycoef[fiber])
coef = legfit(u(y_of_wave, 0, npix_y), wave, deg=ycoef[fiber].size)
wave_of_y[fiber] = legval(u(np.arange(npix_y).astype(float), 0, npix_y), coef)
# Determines wavelength intensity (x) based on Y
x_of_y = legval(u(wave_of_y[fiber], wavemin, wavemax), xcoef[fiber])
# Ascertain X by using low and high uncertainty
x1_of_y = np.floor(x_of_y).astype(int) - 3
x2_of_y = np.floor(x_of_y).astype(int) + 4
return (x1_of_y, x2_of_y)
def vizualize(self, x_left, x_right, points, coefs):
y_interp = legndr.legval(points[0], coefs)
self.q_residual.setText(str(np.linalg.norm(points[1] - y_interp)))
x_interp = np.linspace(-1, 1, len(points[0])*20)
x_interp = np.concatenate((x_interp, points[0]))
x_interp = np.sort(x_interp)
y_interp = legndr.legval(x_interp, coefs)
x_interp = (x_left + x_right) / 2 + (x_right - x_left) / 2 * x_interp
points[0] = (x_left + x_right) / 2 + (x_right - x_left) / 2 * points[0]
plt.plot(points[0], points[1], 'ro')
plt.plot(x_interp, y_interp)
plt.show()
def build_spatial_flux(self):
""" Calculates the flux across all nodes.
Uses current flux_coefficients values.
"""
for node in xrange(self.nodes):
for index in xrange(self.solution_cells):
normalized_index = self.normalized_index(index)
flux_index = self.solution_cells*node+index
coeff_start = self.order*node
coeff_end = self.order*(node+1)
self.flux[0, 1, flux_index] = legval(normalized_index, self.flux_coefficients[1, coeff_start:coeff_end])
self.flux[0, 0, flux_index] = legval(normalized_index, self.flux_coefficients[0, coeff_start:coeff_end])
def Hamiltonian_Legendre_polynomial(c, potential, domain, N):
#potential is a constant in this case
x = np.linspace(-domain / 2, domain / 2, N)
delta_x = domain / (N - 1)
#here, the normalized legendre polynomical has been used
# for the nth polynomials, normalization constant is sqrt(2/(2n + 1))
#kinetic term
K = np.zeros((N, N))
for ii in range(N):
legen_left = np.zeros(N)
legen_left[ii] = mt.sqrt((2 * ii + 1) / 2)
for jj in range(N):
deriva_array = np.zeros(N + 2)
deriva_array[jj] = mt.sqrt((2 * jj + 1) / 2)
legen_right_deriva = legen.legder(deriva_array, 2)
#multiply them
legen_multiply = legen.legmul(legen_left, legen_right_deriva)
#integral
legen_integral = legen.legint(legen_multiply)
#calculate the matrix elements
K[ii][jj] = legen.legval(domain / 2, legen_integral) - \
legen.legval(-domain / 2, legen_integral)
#the S matrix, inside the [-1, 1] domain, the legendre ploynomial can be treatedas basis and satisfying <xi|xj> = delta ij, thus S matrix is a identity matrix
S = np.zeros((N, N))
for ii in range(N):
legen_left_S = np.zeros(N)
legen_left_S[ii] = mt.sqrt((2 * ii + 1) / 2)
legen_multiply_S = legen.legmul(legen_left_S, legen_left_S)
legen_integral_S = legen.legint(legen_multiply_S)
S[ii][ii] = legen.legval(domain / 2, legen_integral_S) - \
legen.legval(-domain / 2, legen_integral_S)
K = K * -1 * c
#because the potential is just a constant here, we can calculate the V matrix simply by multiply the matrix S a constant potential value
V = potential * S
##divide the obtained Hamiltonian by the S matrix
H = K + V
return H
def icb_interface_flux_matrix(p, K, T):
"""The interface flux matrices for the ICB schemes, we use upwinding
to get the fluxes. Denote T the translation necessary to
evaluate the flux from the other cell.
"""
# Enhanced polynomial degree
phat = p + len(K)
G0 = smp.zeros(p + 1, phat + 1)
G1 = smp.zeros(p + 1, phat + 1)
for i in range(0, p + 1):
for j in range(0, phat + 1):
li = L.basis(i)
lj = L.basis(j)
G0[i, j] = leg.legval(-1, li.coef) * \
leg.legval(1, lj.coef) * (T**-1)
G1[i, j] = leg.legval(1, li.coef) * leg.legval(1, lj.coef)
# Enhancement matrix
A, Ainv, B, Binv = enhance.enhancement_matrices(p, K)
# Using the enhanced function in the flux (see notes 21/4/15)
BL = smp.zeros(phat + 1, phat + 1)
BR = smp.zeros(phat + 1, phat + 1)
for i in range(p + 1):
li = L.basis(i)
BL[i, i] = 1 # basis.integrate_legendre_product(li,li)
BR[i, i] = 1 # BL[i,i]
for i, k in enumerate(K):
lk = L.basis(k)
int_lklk = basis.integrate_legendre_product(lk, lk)
BL[i + p + 1, i + p + 1] = T # * int_lklk
BR[i + p + 1, i + p + 1] = (T**(-1)) # * int_lklk
# reduction matrix
R = smp.zeros(phat + 1, p + 1)
for i in range(p + 1):
R[i, i] = 1
for i, k in enumerate(K):
for j in range(p + 1):
R[i + p + 1, j] = auxf.delta(k, j)
# Convert to sympy matrices
G0 = smp.Matrix(G0) * smp.Matrix(Ainv) * BL * R
G1 = smp.Matrix(G1) * smp.Matrix(Ainv) * BL * R
return G0, G1
def icb_interface_flux_matrix(p, K, T):
"""The interface flux matrices for the ICB schemes, we use upwinding
to get the fluxes. Denote T the translation necessary to
evaluate the flux from the other cell.
"""
# Enhanced polynomial degree
phat = p + len(K)
G0 = smp.zeros(p + 1, phat + 1)
G1 = smp.zeros(p + 1, phat + 1)
for i in range(0, p + 1):
for j in range(0, phat + 1):
li = L.basis(i)
lj = L.basis(j)
G0[i, j] = leg.legval(-1, li.coef) * \
leg.legval(1, lj.coef) * (T**-1)
G1[i, j] = leg.legval(1, li.coef) * leg.legval(1, lj.coef)
# Enhancement matrix
A, Ainv, B, Binv = enhance.enhancement_matrices(p, K)
# Using the enhanced function in the flux (see notes 21/4/15)
BL = smp.zeros(phat + 1, phat + 1)
BR = smp.zeros(phat + 1, phat + 1)
for i in range(p + 1):
li = L.basis(i)
BL[i, i] = 1 # basis.integrate_legendre_product(li,li)
BR[i, i] = 1 # BL[i,i]
for i, k in enumerate(K):
lk = L.basis(k)
int_lklk = basis.integrate_legendre_product(lk, lk)
BL[i + p + 1, i + p + 1] = T # * int_lklk
BR[i + p + 1, i + p + 1] = (T**(-1)) # * int_lklk
# reduction matrix
R = smp.zeros(phat + 1, p + 1)
for i in range(p + 1):
R[i, i] = 1
for i, k in enumerate(K):
for j in range(p + 1):
R[i + p + 1, j] = auxf.delta(k, j)
# Convert to sympy matrices
G0 = smp.Matrix(G0) * smp.Matrix(Ainv) * BL * R
G1 = smp.Matrix(G1) * smp.Matrix(Ainv) * BL * R
return G0, G1
def legplot(nterms=6):
"""
Purpose:
calculate (2l+1)/4pi * Pl and plot
Procedure:
Inputs:
nterms: the number of Pl to plot, starting from 0
Returns:
theta values and scaled legendre polynomials
"""
coefs = np.zeros([nterms, nterms])
for coef in range(nterms):
coefs[coef, coef] = ((2 * coef) + 1) / (4 * np.pi)
npoints = 1801
thetavals = np.linspace(0, 180, npoints)
xvals = np.cos(thetavals * np.pi / 180.)
print 'x vals: ', xvals
Pl = np.empty([nterms, npoints])
for ell in range(nterms):
Pl[ell] = legval(xvals, coefs[ell])
#print 'l = ',ell,', scaled Pl = ',Pl[ell]
plt.plot(thetavals, Pl[ell], label='l = ' + str(ell))
plt.xlabel('angle (degrees)')
plt.ylabel('P_l * (2*l+1)/4pi')
plt.title('scaled legendre polynomials')
#plt.legend()
plt.show()
return thetavals, Pl
def get_chi(blorder_max, ydata, xdata, blindex, noise):
"""
Returns the best-fit Legendre polynomial to an input spectra,
based on a comparison of the reduced chi-squared values for each order
of the polynomial.
blorder_max = maximum order of polynomial to fit
ydata = spectrum y values
xdata = spectrum x values
blindex = the indices of the spectra to include in baseline fitting
noise = rms noise of spectrum"""
opts = lsq(legendreLoss, np.zeros(blorder_max + 1), args=(ydata[blindex],
xdata[blindex],
noise), loss='arctan')
chis = [] # first entry is order=1, second is order=2, ..., up to order=blorder
ymods = []
# Loop through each order of polynomial and create model baseline
# and calculate that model's chi-squared values
for i in np.arange(blorder_max)+1:
# i is the polynomial order
ymod = legendre.legval(xdata, np.array(opts.x)[0:i+1]) #+1 to get last term
ymods.append(ymod)
chi = redchisqg(ydata,ymod,deg=i+1)
chis.append(chi)
# Find the model with the lowest chi-squared value
find_low = np.where(np.array(chis)==min(chis))
low_model = np.array(ymods)[find_low]
return ymod
def test_legvander(self) :
# check for 1d x
x = np.arange(3)
v = leg.legvander(x, 3)
assert_(v.shape == (3, 4))
for i in range(4) :
coef = [0]*i + [1]
assert_almost_equal(v[..., i], leg.legval(x, coef))
# check for 2d x
x = np.array([[1, 2], [3, 4], [5, 6]])
v = leg.legvander(x, 3)
assert_(v.shape == (3, 2, 4))
for i in range(4) :
coef = [0]*i + [1]
assert_almost_equal(v[..., i], leg.legval(x, coef))
def leg_l(l_index, numgrid): leg_access = np.zeros(l_index + 1) leg_access[l_index] = 1 #print leg_access x = np.linspace(0,1,numgrid) y = LG.legval(x, leg_access) return x,y
def cheb_fitcurve(x, y, order):
x = cheb.chebpts2(len(x))
order = 64
coef = legend.legfit(x, y, order)
assert_equal(len(coef), order + 1)
y1 = legend.legval(x, coef)
err_1 = np.linalg.norm(y1 - y) / np.linalg.norm(y)
coef = cheb.chebfit(x, y, order)
assert_equal(len(coef), order + 1)
thrsh = abs(coef[0] / 1000)
for i in range(len(coef)):
if abs(coef[i]) < thrsh:
coef = coef[0:i + 1]
break
y2 = cheb.chebval(x, coef)
err_2 = np.linalg.norm(y2 - y) / np.linalg.norm(y)
plt.plot(x, y2, '.')
plt.plot(x, y, '-')
plt.title("nPt={} order={} err_cheby={:.6g} err_legend={:.6g}".format(
len(x), order, err_2, err_1))
plt.show()
assert_almost_equal(cheb.chebval(x, coef), y)
#
return coef
def _sph_coefs_to_corr( self ):
"""
computes correlation from legendre polynomial coefficients computed from spherical
harmonic coefficients
sets coefficients of order-l polynomials to zero
"""
self.corr = np.zeros( (self.n_q, self.n_q, self.n_psi) )
self.cospsi = np.linspace(-1,1, self.n_psi, endpoint=True)
# Cl = Cl[:(Lmax+1),:,:]
for i in range(self.n_q):
for j in range(i, self.n_q):
coefs = self.cl[:,i,j]
# even_coefs = Cl[:int(Lmax/2),i,j]
# even_coefs= self.cl[::2,i,j]
# for idx in range(even_coefs.size * 2):
# if idx%2 ==0:
# coefs.append(even_coefs[idx/2])
# else:
# coefs.append(0)
# coefs = np.array(coefs)
self.corr[i,j,:] = legval( self.cospsi, coefs )
self.corr[j,i,:] = self.corr[i,j,:] # copy it to the lower triangle too
def test_legvander(self) :
# check for 1d x
x = np.arange(3)
v = leg.legvander(x, 3)
assert_(v.shape == (3, 4))
for i in range(4) :
coef = [0]*i + [1]
assert_almost_equal(v[..., i], leg.legval(x, coef))
# check for 2d x
x = np.array([[1, 2], [3, 4], [5, 6]])
v = leg.legvander(x, 3)
assert_(v.shape == (3, 2, 4))
for i in range(4) :
coef = [0]*i + [1]
assert_almost_equal(v[..., i], leg.legval(x, coef))
def _get_weights(num_points, inner_nodes):
from numpy.polynomial import legendre
base_weight = 2.0 / (num_points * (num_points - 1))
p_n_minus1 = [0] * (num_points - 1) + [1]
p_n_minus1_at_nodes = legendre.legval(inner_nodes, p_n_minus1)
return base_weight / p_n_minus1_at_nodes**2
def baselineWithAmmonia(y,
v,
baselineIndex,
freqthrow=4.11 * u.MHz,
v0=8.5,
sigmav=1.0 * u.km / u.s,
line='oneone',
blorder=5,
noiserms=None):
x = np.linspace(-1, 1, len(y))
chthrow = (freqthrow.to(u.Hz).value / acons.freq_dict[line] * 299792.458 /
np.abs(v[0] - v[1]))
chthrow = (np.round(chthrow)).astype(np.int)
if noiserms is None:
noiserms = mad1d((y - np.roll(y, -2))[baselineIndex])
opts = lsq(
ammoniaLoss,
np.r_[[
np.nanmax(y[baselineIndex]), v[np.nanargmax(y[baselineIndex])], 1.0
],
np.zeros(blorder + 1)],
args=(y[baselineIndex], x[baselineIndex], v[baselineIndex], noiserms),
kwargs={'chthrow': chthrow},
loss='soft_l1')
return y - legendre.legval(x, opts.x[3:])
def chisq_leg(p, x, y, w, flag_call): ind = np.where(flag_call==1)[0] y_c = y[ind] x_c = x[ind] w_c = w[ind] chisq = np.sum( (1/(w_c)**2)*(leg.legval(x_c, p) - y_c)**2 ) / np.sum(1/w_c**2) return chisq
def basisMatrixLegendre(x,order):
'''
Builds (order+1,x) 2-d array of Legendre polynomials evaluated at x
Parameters
----------
x: numpy 1-d array
Points at which to evaluate basis functions
order:
Maximum order of polynomial set
Returns
-------
legmtx: numpy 2d array of shape (order+1,x)
Legendre polynomials evaluated at x
'''
### Construct matrix of Legendre polynomials
legmtx = np.zeros((order+1,len(x)))
### Prepare matrix of Leg. poly. basis functions evaluated at x
for i in range(order+1):
coeffs=np.zeros(i+1)
coeffs[i]=1.
legmtx[i,:]=L.legval(x, coeffs)
return legmtx
def Likelihood_Sph(vertex, *args):
coeff, PMT_pos, event_pe, cut = args
y = event_pe
# fixed axis
z = np.sqrt(np.sum(vertex[1:4]**2)) / shell
if (np.abs(z) > 1):
z = np.sign(z)
cos_theta = np.sum(vertex[1:4]*PMT_pos,axis=1)\
/np.sqrt(np.sum(vertex[1:4]**2)*np.sum(PMT_pos**2,axis=1))
# accurancy and nan value
cos_theta = np.nan_to_num(cos_theta)
cos_theta[cos_theta > 1] = 1
cos_theta[cos_theta < -1] = -1
size = np.size(PMT_pos[:, 0])
x = np.zeros((size, cut))
# legendre coeff
for i in np.arange(0, cut):
c = np.zeros(cut)
c[i] = 1
x[:, i] = LG.legval(cos_theta, c)
k = np.zeros(cut)
for i in np.arange(cut):
# cubic interp
k[i] = np.sum(np.polynomial.legendre.legval(z, coeff[i, :]))
#k[0] = k[0] + np.log(vertex[0])
k[0] = vertex[0]
expect = np.exp(np.dot(x, k))
L = -np.sum(np.sum(np.log((expect**y) * np.exp(-expect))))
return L
def baselineSpectrum(spectrum,order=1,baselineIndex=()):
x=np.arange(len(spectrum))
coeffs = legendre.legfit(x[baselineIndex],spectrum[baselineIndex],order)
# pdb.set_trace()
spectrum -= legendre.legval(x,coeffs)
return(spectrum)
def baselineSpectrum(spectrum,order=1,baselineIndex=()):
x=np.arange(len(spectrum))
coeffs = legendre.legfit(x[baselineIndex],spectrum[baselineIndex],order)
# pdb.set_trace()
spectrum -= legendre.legval(x,coeffs)
return(spectrum)
def work(j):
i, order = annotation[j]
c = numpy.zeros(5)
c[order] = 1
# watch out the eigenmode is wikipedia
# no negative phase on 2nd order pole!
eigenmode = eigenmodes[j]
eigenmode[i].xi[...] = \
powerspec.pole(eigenmode[i].r, order=order)[:, None] \
* legval(eigenmode[i].mu, c)[None, :]
def robustBaseline(y, baselineIndex, blorder=1, noiserms=None):
x = np.linspace(-1, 1, len(y))
if noiserms is None:
noiserms = mad1d((y - np.roll(y, -2))[baselineIndex])
opts = lsq(legendreLoss, np.zeros(blorder + 1), args=(y[baselineIndex],
x[baselineIndex],
noiserms),
loss='arctan')
return y - legendre.legval(x, opts.x)
def test_legfit(self) :
def f(x) :
return x*(x - 1)*(x - 2)
# Test exceptions
assert_raises(ValueError, leg.legfit, [1], [1], -1)
assert_raises(TypeError, leg.legfit, [[1]], [1], 0)
assert_raises(TypeError, leg.legfit, [], [1], 0)
assert_raises(TypeError, leg.legfit, [1], [[[1]]], 0)
assert_raises(TypeError, leg.legfit, [1, 2], [1], 0)
assert_raises(TypeError, leg.legfit, [1], [1, 2], 0)
assert_raises(TypeError, leg.legfit, [1], [1], 0, w=[[1]])
assert_raises(TypeError, leg.legfit, [1], [1], 0, w=[1, 1])
# Test fit
x = np.linspace(0, 2)
y = f(x)
#
coef3 = leg.legfit(x, y, 3)
assert_equal(len(coef3), 4)
assert_almost_equal(leg.legval(x, coef3), y)
#
coef4 = leg.legfit(x, y, 4)
assert_equal(len(coef4), 5)
assert_almost_equal(leg.legval(x, coef4), y)
#
coef2d = leg.legfit(x, np.array([y, y]).T, 3)
assert_almost_equal(coef2d, np.array([coef3, coef3]).T)
# test weighting
w = np.zeros_like(x)
yw = y.copy()
w[1::2] = 1
y[0::2] = 0
wcoef3 = leg.legfit(x, yw, 3, w=w)
assert_almost_equal(wcoef3, coef3)
#
wcoef2d = leg.legfit(x, np.array([yw, yw]).T, 3, w=w)
assert_almost_equal(wcoef2d, np.array([coef3, coef3]).T)
# test scaling with complex values x points whose square
# is zero when summed.
x = [1, 1j, -1, -1j]
assert_almost_equal(leg.legfit(x, x, 1), [0, 1])
def test_legfromroots(self) :
res = leg.legfromroots([])
assert_almost_equal(trim(res), [1])
for i in range(1,5) :
roots = np.cos(np.linspace(-np.pi, 0, 2*i + 1)[1::2])
pol = leg.legfromroots(roots)
res = leg.legval(roots, pol)
tgt = 0
assert_(len(pol) == i + 1)
assert_almost_equal(leg.leg2poly(pol)[-1], 1)
assert_almost_equal(res, tgt)
def test_legval(self):
#check empty input
assert_equal(leg.legval([], [1]).size, 0)
#check normal input)
x = np.linspace(-1, 1)
y = [polyval(x, c) for c in Llist]
for i in range(10):
msg = "At i=%d" % i
tgt = y[i]
res = leg.legval(x, [0]*i + [1])
assert_almost_equal(res, tgt, err_msg=msg)
#check that shape is preserved
for i in range(3):
dims = [2]*i
x = np.zeros(dims)
assert_equal(leg.legval(x, [1]).shape, dims)
assert_equal(leg.legval(x, [1, 0]).shape, dims)
assert_equal(leg.legval(x, [1, 0, 0]).shape, dims)
def dg_interface_flux_matrix(p, T):
"""The interface flux matrices, we use upwinding to get the fluxes
Denote T the translation necessary to evaluate the flux from the
other cell.
There are also analytical expressions for these. See my thesis page 73.
"""
G0 = smp.zeros(p + 1)
G1 = smp.zeros(p + 1)
for i in range(0, p + 1):
for j in range(0, p + 1):
li = L.basis(i)
lj = L.basis(j)
G0[i, j] = leg.legval(-1, li.coef) * \
leg.legval(1, lj.coef) * (T**-1)
G1[i, j] = leg.legval(1, li.coef) * leg.legval(1, lj.coef)
return G0, G1
def __worker(rbin):
rr = r[rbin]
# Axis distribution beta parameters
beta_axis = beta_coeffs_point(
rr, self.coef, self.kmax, self.rkstep,
self.sigma, self.lmax, oddl, truncate)
# Detection function beta parameters in the detection frame
beta_df = beta_coeffs_point(
rr, df.coef, df.kmax, df.rkstep,
df.sigma, df.lmax, df_oddl, truncate)
# Detection function beta parameters in the lab frame
beta_df = beta_df[0:lmax + 1] * plbeta
# The following is too slow
# res = scipy.optimize.basinhopping(
# lambda x: -legendre.legval(x, beta_df),
# [0.0], stepsize = 1.0/lmax, T=1.0,
# minimizer_kwargs=dict(method='TNC', bounds=((-1.0,1.0),))
# )
# Find approximate position of maxmimum. Note that there
# are lmax maxima/minima between -1..1, so this value of
# Ns should suffice.
res = scipy.optimize.brute(
lambda x, *args: -legendre.legval(x, beta_df),
((-1.0, 1.0),), Ns=5.0 * lmax,
)
# Refine position of maximum - note that the 'finish'
# option of optimize.brute doesn't work with fmin_tnc etc
respolish = scipy.optimize.minimize(lambda x: -legendre.legval(x, beta_df),
[res[0]], bounds=((-1.0,1.0),), method='TNC')
maxval = -respolish.fun
beta = beta_axis[0:lmax + 1] * beta_df[0:lmax + 1] * wt
overlap[rbin] = beta.sum() / maxval
def get_basis(deg, dofset=None):
# Legendre polynomials are used as the basis of polynomials. In the basis of
# Legendre polynomials is row of eye
polyset = np.eye(deg+1)
if dofset is None: dofset = np.linspace(-1, 1, deg+1)
# Reatange dofs to have external first
dofset = np.r_[dofset[0], dofset[-1], dofset[1:-1]]
# Compute the nodal matrix
A = np.array([legval(dofset, base) for base in polyset])
# New coefficients
B = np.linalg.inv(A)
# Combine the basis according to new weights
basis = [lambda x, c=c: legval(x, c) for c in B]
# Check that the basis is nodal
assert np.allclose(np.array([f(dofset) for f in basis]), polyset)
# First deriv
dbasis = [lambda x, c=legder(c): legval(x, c) for c in B]
return basis, dbasis
def test_legval(self) :
def f(x) :
return x*(x**2 - 1)
#check empty input
assert_equal(leg.legval([], [1]).size, 0)
#check normal input)
for i in range(10) :
msg = "At i=%d" % i
ser = np.zeros
tgt = self.y[i]
res = leg.legval(self.x, [0]*i + [1])
assert_almost_equal(res, tgt, err_msg=msg)
#check that shape is preserved
for i in range(3) :
dims = [2]*i
x = np.zeros(dims)
assert_equal(leg.legval(x, [1]).shape, dims)
assert_equal(leg.legval(x, [1,0]).shape, dims)
assert_equal(leg.legval(x, [1,0,0]).shape, dims)
def leg_proj_legguass(x, signal, weights,lmax):
"""projection into legendre polynomial using gauss-legendre polynomial
"""
coefs = np.zeros(lmax + 1)
weights_sum = np.sum(weights)
for l in range(lmax + 1):
if l%2==0:
cc = np.zeros(l+1)
cc[l] = 1
coefs[l] = np.sum( weights*legval(x,cc)*signal) / weights_sum*(2*l+1)
return coefs
def eval(pname,fiber,wavelength,verbose=False) :
legdeg=hdulist[1].header["LEGDEG"]
table=hdulist[1].data
paramindex=numpy.where(table["PARAM"]==pname)[0][0]
wavemin=table["WAVEMIN"][paramindex]
wavemax=table["WAVEMAX"][paramindex]
fiber_coeffs=table["COEFF"][paramindex][fiber]
wr=2*(wavelength-(wavemin+wavemax)/2)/(wavemax-wavemin)
val=legval(wr,fiber_coeffs)
if verbose :
print pname,"fiber=",fiber,"wave=",wavelength,"wrange=",wavemin,wavemax,"coefs=",fiber_coeffs,"val=",val
return val
def coeff_fig():
"""Plots a sorted degree sequence and its polynomial fit (used in lifting/restriction diagram). Also plots evolution of coefficients over time for both a cpi routine and a direct simulation (currently not included in manuscript).
**To generate data:**::
mpirun -n 50 ./pref_attach -n 100 -m 50000 -nms 1000000 -omw 100000 -ci 10000 -pStep 500000
mpirun -n 50 ./pref_attach -n 100 -m 50000 -nms 1000000 -omw 100000 -ci 10000 -pStep 500000 -noinit
cp ./paper-data/other-runs/withinitfitted_coeffs0.csv ./manuscript-materials/data
cp ./paper-data/other-runs/withinitpre_proj_degs0.csv ./manuscript-materials/data
cp ./paper-data/other-runs/withinittimes0.csv ./manuscript-materials/data
cp ./paper-data/other-runs/noinittimes0.csv ./manuscript-materials/data
cp ./paper-data/other-runs/noinitfitted_coeffs0.csv ./manuscript-materials/data
cp ./paper-data/other-runs/noinitpre_proj_degs0.csv ./manuscript-materials/data
"""
init = "noinit"
times = np.genfromtxt(data_directory + init + 'times0.csv', delimiter=',', skip_header=True)
degs = np.genfromtxt(data_directory + init + 'pre_proj_degs0.csv', delimiter=',', skip_header=True)
fitted_coeffs = np.genfromtxt(data_directory + init + 'fitted_coeffs0.csv', delimiter=',', skip_header=True)
init = "withinit"
times_cpi = np.genfromtxt(data_directory + init + 'times0.csv', delimiter=',', skip_header=True)
degs_cpi = np.genfromtxt(data_directory + init + 'pre_proj_degs0.csv', delimiter=',', skip_header=True)
fitted_coeffs_cpi = np.genfromtxt(data_directory + init + 'fitted_coeffs0.csv', delimiter=',', skip_header=True)
gsize = degs.shape[1]
fig = plt.figure()
ax = fig.add_subplot(111)
index = 50 # arbitrary index, should show some curvature
ax.scatter(np.arange(gsize), degs[index], label='Sorted degree sequence')
ax.plot(np.arange(gsize), npl.legval(np.arange(gsize), fitted_coeffs[index]), c='r', label='Polynomial fit')
ax.set_xlim((0,gsize))
ax.set_xlabel('Vertex')
ax.set_ylabel('Degree')
ax.legend(loc=4, fontsize=42)
fig.subplots_adjust(left=0.1, bottom=0.11)
ncoeffs = fitted_coeffs.shape[1]
for i in range(ncoeffs):
fig = plt.figure()
ax = fig.add_subplot(111)
ax.scatter(times, fitted_coeffs[:,i], label='Direct simulation')
ax.scatter(times_cpi, fitted_coeffs_cpi[:,i], label='CPI')
ax.set_xlabel('Step')
ax.set_ylabel(r'$c_' + str(i) + '$')
ax.legend()
plt.show()
def test_legendre_val():
"""Test Legendre polynomial (derivative) equivalence
"""
rng = np.random.RandomState(0)
# check table equiv
xs = np.linspace(-1., 1., 1000)
n_terms = 100
# True, numpy
vals_np = legendre.legvander(xs, n_terms - 1)
# Table approximation
for fun, nc in zip([_get_legen_lut_fast, _get_legen_lut_accurate],
[100, 50]):
lut, n_fact = _get_legen_table('eeg', n_coeff=nc, force_calc=True)
vals_i = fun(xs, lut)
# Need a "1:" here because we omit the first coefficient in our table!
assert_allclose(vals_np[:, 1:vals_i.shape[1] + 1], vals_i,
rtol=1e-2, atol=5e-3)
# Now let's look at our sums
ctheta = rng.rand(20, 30) * 2.0 - 1.0
beta = rng.rand(20, 30) * 0.8
lut_fun = partial(fun, lut=lut)
c1 = _comp_sum_eeg(beta.flatten(), ctheta.flatten(), lut_fun, n_fact)
c1.shape = beta.shape
# compare to numpy
n = np.arange(1, n_terms, dtype=float)[:, np.newaxis, np.newaxis]
coeffs = np.zeros((n_terms,) + beta.shape)
coeffs[1:] = (np.cumprod([beta] * (n_terms - 1), axis=0) *
(2.0 * n + 1.0) * (2.0 * n + 1.0) / n)
# can't use tensor=False here b/c it isn't in old numpy
c2 = np.empty((20, 30))
for ci1 in range(20):
for ci2 in range(30):
c2[ci1, ci2] = legendre.legval(ctheta[ci1, ci2],
coeffs[:, ci1, ci2])
assert_allclose(c1, c2, 1e-2, 1e-3) # close enough...
# compare fast and slow for MEG
ctheta = rng.rand(20 * 30) * 2.0 - 1.0
beta = rng.rand(20 * 30) * 0.8
lut, n_fact = _get_legen_table('meg', n_coeff=10, force_calc=True)
fun = partial(_get_legen_lut_fast, lut=lut)
coeffs = _comp_sums_meg(beta, ctheta, fun, n_fact, False)
lut, n_fact = _get_legen_table('meg', n_coeff=20, force_calc=True)
fun = partial(_get_legen_lut_accurate, lut=lut)
coeffs = _comp_sums_meg(beta, ctheta, fun, n_fact, False)
def recompute_legendre_coefficients(xcoef,ycoef,wavemin,wavemax,degxx,degxy,degyx,degyy,dx_coeff,dy_coeff) :
"""
Modifies legendre coefficients of an input trace set using polynomial coefficents (as defined by the routine monomials)
Args:
xcoef : 2D np.array of shape (nfibers,ncoef) containing Legendre coefficents for each fiber to convert wavelenght to XCCD
ycoef : 2D np.array of shape (nfibers,ncoef) containing Legendre coefficents for each fiber to convert wavelenght to YCCD
wavemin : float
wavemax : float. wavemin and wavemax are used to define a reduced variable legx(wave,wavemin,wavemax)=2*(wave-wavemin)/(wavemax-wavemin)-1
used to compute the traces, xccd=legval(legx(wave,wavemin,wavemax),xtrace[fiber])
degxx : int, degree of polynomial for x shifts as a function of x (x is axis=1 in numpy image array, AXIS=0 in FITS, cross-dispersion axis = fiber number direction)
degxy : int, degree of polynomial for x shifts as a function of y (y is axis=0 in numpy image array, AXIS=1 in FITS, wavelength dispersion axis)
degyx : int, degree of polynomial for y shifts as a function of x
degyy : int, degree of polynomial for y shifts as a function of y
dx_coeff : 1D np.array of polynomial coefficients of size (degxx*degxy) as defined by the routine monomials.
dy_coeff : 1D np.array of polynomial coefficients of size (degyx*degyy) as defined by the routine monomials.
Returns:
xcoef : 2D np.array of shape (nfibers,ncoef) with modified Legendre coefficents
ycoef : 2D np.array of shape (nfibers,ncoef) with modified Legendre coefficents
"""
wave=np.linspace(wavemin,wavemax,100)
nfibers=xcoef.shape[0]
rw=legx(wave,wavemin,wavemax)
for fiber in range(nfibers) :
x = legval(rw,xcoef[fiber])
y = legval(rw,ycoef[fiber])
m=monomials(x,y,degxx,degxy)
dx=m.T.dot(dx_coeff)
xcoef[fiber]=legfit(rw,x+dx,deg=xcoef.shape[1]-1)
m=monomials(x,y,degyx,degyy)
dy=m.T.dot(dy_coeff)
ycoef[fiber]=legfit(rw,y+dy,deg=ycoef.shape[1]-1)
return xcoef,ycoef
def test_evenly_spaced(self):
import numpy as np
from numpy.polynomial import legendre
import six
num_points = 17
points = np.linspace(0, 1, num_points)
result = self._call_func_under_test(points)
self.assertEqual(result.shape, (num_points, num_points))
self.assertTrue(result.flags.f_contiguous)
expected_result = np.zeros((num_points, num_points))
for n in six.moves.xrange(num_points):
leg_coeffs = [0] * n + [1]
expected_result[:, n] = legendre.legval(points, leg_coeffs)
self.assertTrue(np.allclose(result, expected_result))
frob_err = np.linalg.norm(result - expected_result, ord='fro')
self.assertTrue(frob_err < 1e-13)
def _calc_h(cosang, stiffness=4, num_lterms=50):
"""Calculate spherical spline h function between points on a sphere.
Parameters
----------
cosang : array-like of float, shape(n_channels, n_channels)
cosine of angles between pairs of points on a spherical surface. This
is equivalent to the dot product of unit vectors.
stiffness : float
stiffness of the spline. Also referred to as `m`.
num_lterms : int
number of Legendre terms to evaluate.
H : np.ndrarray of float, shape(n_channels, n_channels)
The H matrix.
"""
factors = [(2 * n + 1) /
(n ** (stiffness - 1) * (n + 1) ** (stiffness - 1) * 4 * np.pi)
for n in range(1, num_lterms + 1)]
return legval(cosang, [0] + factors)
def contFitLegendreAboutLine(wave,flux,err,restlam,z,velfitregions,uniform=True,**kwargs):
'''
Fits a continuum over a spectral region using the formalism of Sembach
& Savage 1992, estimating the uncertainty at each point of the continuum.
Parameters
----------
wave
flux
err
restlam
z
velfitregions
uniform
Returns
-------
'''
vels=joebgoodies.veltrans(z,wave,restlam)
### Find indices corresponding to velocities defined in velfitregions
fitidxs=[]
for reg in velfitregions:
thesevels=np.where((vels>=reg[0])&(vels<=reg[1]))[0]
fitidxs.extend(thesevels)
if uniform != True:
fitsol,err,parsol,errmtx,scalefac = fitLegendre(vels[fitidxs],flux[fitidxs],
sig=err[fitidxs],**kwargs)
else:
fitsol,err,parsol,errmtx,scalefac = fitLegendre(vels[fitidxs],flux[fitidxs],**kwargs)
### Normalize x so that domain of fit is -1 to +1
vscale = vels/scalefac # must scale to fitted domain
### Evaluate continuum using all points, not just those in fit regions
continuum = L.legval(vels/scalefac,parsol)
err = errorsLegendre(vscale,errmtx)
return wave,continuum,err
