I've added form_compiler_parameters to project so I can set the
quadrature degree (passed on to the two assemble calls).
This code, using "lu", still shows some problems:
def test2(qd):
ffc_opt = { 'representation': 'quadrature', 'quadrature_degree': qd }
mesh = UnitSquare(50, 50)
V = FunctionSpace(mesh, "DG", 1)
u = project(triangle.x[0], V, solver_type="lu",
form_compiler_parameters=ffc_opt)
a = u.dx(0)*dx
M = assemble(u.dx(0)*dx, form_compiler_parameters=ffc_opt)
uv = u.vector()[:]
print uv.min(), uv.max(), M
test2(1)
test2(2)
test2(3)
test2('auto')
Output:
nan nan nan
-1.11173074327e-17 1.0 1.0
-9.52912065661e-18 1.0 1.0
0.00666666666667 0.993333333333 8.77744057992e-16
with qd = 2, 3, it looks good, with 1 or 'auto' we have nan or zero.
--
You received this bug notification because you are a member of DOLFIN
Team, which is subscribed to DOLFIN.
https://bugs.launchpad.net/bugs/785874
Title:
Projection of x is not accurate
Status in DOLFIN:
New
Bug description:
I've tested that projecting x works without the scaling bug that was
just fixed, using dimensions 1,2,3 and both DG and CG from 0 to 3
degrees. I print the max and min values of the vector of the
projection function, and the values are _close_ to 0 and 1 but not to
machine precision. The script is below.
There's up to 2.7% error in the 3D case. Is the projection form
integrated accurately enough? All but the DG0 function space should be
capable of representing x exactly. Not sure if this is a dolfin or ffc
bug.
from dolfin import *
def mcx(dim):
if dim == 1:
mesh = UnitInterval(20)
cell = interval
x = cell.x
if dim == 2:
mesh = UnitSquare(20, 20)
cell = triangle
x = cell.x[0]
if dim == 3:
mesh = UnitCube(20, 20, 20)
cell = tetrahedron
x = cell.x[0]
return mesh, cell, x
for dim in range(1, 4):
mesh, cell, x = mcx(dim)
minval, maxval = 1.0, 0.0
#print dim, "DG"
for degree in range(3):
V = FunctionSpace(mesh, "DG", degree)
u = project(x, V)
#print dim, degree, u.vector().min(), u.vector().max()
minval = min(minval, u.vector().min())
maxval = max(maxval, u.vector().max())
#print dim, "CG"
for degree in range(1, 4):
V = FunctionSpace(mesh, "CG", degree)
u = project(x, V)
#print dim, degree, u.vector().min(), u.vector().max()
minval = min(minval, u.vector().min())
maxval = max(maxval, u.vector().max())
print minval, maxval
_______________________________________________
Mailing list: https://launchpad.net/~dolfin
Post to : dolfin@lists.launchpad.net
Unsubscribe : https://launchpad.net/~dolfin
More help : https://help.launchpad.net/ListHelp
