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利用C

This test program solves Poisson's equation

    - div grad u = f

on the unit square and on the unit cube with homogeneous Dirichlet
boundary conditions.

In 2D, the right-hand side f is given by

    f(x, y) = 2 pi^2 sin(x) sin(y)

and the exact solution is u(x, y) = sin(x) sin(y).

In 3D, the right-hand side f is given by

    f(x, y) = 3 pi^2 sin(x) sin(y) sin(z)

and the exact solution is u(x, y) = sin(x) sin(y) sin(z).

The solution is computed with Lagrange finite elements of degree 1-5
and the error is computed in the maximum norm (maximum taken only over
the values at vertices).

Here are the results (2005-06-30, DOLFIN version 0.5.7+):

Maximum norm error in 2D:
-------------------------

      | h = 1/2   h = 1/4   h = 1/8
------------------------------------
q = 1 | 3.831e-01 1.375e-01 3.748e-02
q = 2 | 1.067e-02 1.782e-03 1.480e-04
q = 3 | 3.675e-03 5.417e-04 4.243e-05
q = 4 | 1.027e-03 2.644e-05 4.862e-07
q = 5 | 1.639e-05 1.803e-06 3.985e-08

Maximum norm error in 3D:
-------------------------

      | h = 1/2   h = 1/4   h = 1/8
------------------------------------
q = 1 | 5.065e-01 2.129e-01 6.127e-02
q = 2 | 3.890e-02 6.874e-03 5.589e-04
q = 3 | 1.088e-03 1.722e-03 1.535e-04
q = 4 | 6.868e-03 2.154e-04 3.983e-06
q = 5 | 3.821e-04 1.450e-05 3.598e-07