Add commentary to a test case.

diff --git a/tests/sundials/kinsol_01.cc b/tests/sundials/kinsol_01.cc
index 6e16c5ce8175b4a46b123506f41eef54aa6e479f..d51db8620c7e3ca3ba5066f21634b15553623681 100644 (file)
--- a/tests/sundials/kinsol_01.cc
+++ b/tests/sundials/kinsol_01.cc
@@ -22,7 +22,10 @@
 
 #include "../tests.h"
 
-// provide only residual function, use internal solver.
+// Solve a nonlinear system but provide only residual function. KINSOL
+// then uses its internal solvers which are based on a
+// finite-difference approximation to the Jacobian and a direct
+// solver.
 
 /**
  * Solve the non linear problem