On 13 June 2011 16:07, Neilen Marais <nmar...@gmail.com> wrote: > Hi, > > Has the calculation of auto quadrature order changed recently?
Yes, UFL revno: 1088. This changeset updated the estimate_total_polynomial_degree() function to take into account spatial coordinates when computing the degree. Try something like this in your code: from ufl.algorithms import estimate_total_polynomial_degree ... print "L degree: ", estimate_total_polynomial_degree(L) to see if the degree is conservative enough for your application, then you can decide if you want to leave the default degree at 'auto' or specify it yourself. Kristian > I've set up the electromagnetic near-to-farfield transform based on > the integral of tangential electric and magnetic fields around the > boundary of the problem. I got incorrect results on a canonical test > problem and wasn't sure of the source of the error. I'm evaluating > complex integrals like: > > L = surface_integral_over_Gamma( (-n x E(r_prime) ) > e^(j*k0*dot(r_prime, r_hat))ds(r_prime) ) > > where E is the E-field vector, r_hat is a unit vector pointing in the > far-field observation direction and r_prime is the integration > coordinate and Gamma is the closed near-to-farfield transform surface. > Since the integrals are complex, I had to split them up into several > real integrals making the whole thing quite complicated. In real > components, the complex exponential is of course broken into sin/cos > terms. Since E is a vector quantity, I also needed to take the dot > product with unit vectors, so the final forms looked like: > > from dolfin import * > V = FunctionSpace(mesh, "Nedelec 1st kind H(curl)", 2) > E_r = Function(V) # real part > E_i = Function(V) # imaginary part > .... > phase = k0*dot(r_prime, rhat) > n = V.cell().n > rprime = V.cell().x > > # theta and phi are the far-field observation angles > import math > rhat_ = math.sin(theta)*math.cos(phi), math.sin(theta)*math.sin(phi), > math.cos(theta)]) > theta_hat_ = math.cos(theta)*N.cos(phi), > math.cos(theta)*math.sin(phi), -math.sin(theta)] > rhat = Constant(rhat_) > theta_hat = Constant(theta_hat_) > > M_r = -cross(n, E_r) > M_i = -cross(n, E_i) > L_r_theta = dot(theta_hat, M_r*cos(phase) - M_i*sin(phase))*ds # real > part of Theta component of L > > After some experimentation I manually specified the integration order, > and suddenlty the results seemed quite good! What is strange is that I > could not replecate the bad 'auto' order results, even by specifying > zero or first order integration. Today I upgraded my fenics > installation to the latest development version, and now the auto > results are also looking good. I realise that the inclusion of the > cos/sin terms complicate matters somewhat, but I would just like to > have a feeling for what is going on with the auto quadrature. Would it > be sensible to leave the quadrature order default at 'auto' going > forward, or should I rather be setting it explicitly? > > Thanks > Neilen > > _______________________________________________ > Mailing list: https://launchpad.net/~dolfin > Post to : dolfin@lists.launchpad.net > Unsubscribe : https://launchpad.net/~dolfin > More help : https://help.launchpad.net/ListHelp > _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : dolfin@lists.launchpad.net Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
