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Message #23591
Re: [Bug 785874] Re: Projection of x is not accurate
On Mon, May 30, 2011 at 09:53:42PM -0000, Martin Sandve Alnæs wrote:
> There's two, don't remember what they do:
> def estimate_max_polynomial_degree(e, default_degree=1):
> def estimate_total_polynomial_degree(e, default_degree=1):
> in algorithms/transformations.py (should rather be in analysis.py I guess).
>
> ** Changed in: dolfin
> Status: New => Invalid
And those include spatial coordinates?
--
Anders
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https://bugs.launchpad.net/bugs/785874
Title:
Projection of x is not accurate
Status in DOLFIN:
Invalid
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
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