# [Commits] [svn:einsteintoolkit] www/about/gallery/ (Rev. 1489)

www-push at einsteintoolkit.org www-push at einsteintoolkit.org
Tue Oct 13 11:48:55 CDT 2015

```User: www-push
Date: 2015/10/13 11:48 AM

Modified:
incoming.php

Log:
Update elliptic solver gallery example text

Text provided by Eloisa Bentivegna (23-Jun-2015).

File Changes:

==========================

File [modified]: incoming.php
Delta lines: +8 -7
===================================================================
--- about/gallery/incoming.php	2015-08-31 14:51:07 UTC (rev 1488)
+++ about/gallery/incoming.php	2015-10-13 16:48:55 UTC (rev 1489)
@@ -12,13 +12,14 @@
Poisson equation with
the <a href="https://bitbucket.org/eloisa/cosmology/src/master/CT_MultiLevel/?at=master">CT_MultiLevel</a>
elliptic solver.  <a href="poisson/doc/CT_MultiLevel/documentation.html">Documentation</a> for CT_MultiLevel is available.
-  <p>This simulation shows how to solve an elliptic equation.  The
-  source term and boundary conditions are specified via grid
-  functions, in this case provided by the CT_Analytic thorn.  Fixed
-  mesh refinement concentrates points in the neighbourhood of the
-  Gaussians, and a multigrid algorithm is used to solve the Poisson
-  equation.  The plots below show the converged solution, and the norm
-  of the solution error as a function of time.</p>
+  <p>This example shows how to solve the Poisson equation with a generic
+  source term. To assess the performance of the algorithm, we start by
+  prescribing a solution phi0 (in this case, a superposition of Gaussian
+  functions), and construct the source term by taking the Laplacian of
+  phi0. The plots show the final solution phi (color plot), the source term
+  (white contour surfaces) and the solution error phi-phi0 as a function
+  of the iteration number.</p>
+
<table>
<tr><th>Parameter file</th><td><a href="poisson/poisson.par">poisson.par</a></td></tr>
<tr><th>Thornlist</th><td><a href="poisson/poisson.th">poisson.th</a></td></tr>

```