Merge pull request #60 from scientificcomputing/finsberg/solver-tolerance

Set default tolerance to 1e-6 rather than 1e-10

Author: finsberg

src/scifem/solvers.py

@@ -99,7 +99,7 @@ def set_post_solve_callback(self, callback: Callable[["NewtonSolver"], None]):
         """Set a callback function that is called after each Newton iteration."""
         self._post_solve_callback = callback
 
-    def solve(self, atol=1e-10, rtol=1e-10, beta=1.0) -> int:
+    def solve(self, atol=1e-6, rtol=1e-6, beta=1.0) -> int:
         """Solve the nonlinear problem using Newton's method.
 
         Args:
@@ -208,7 +208,7 @@ def solve(self, atol=1e-10, rtol=1e-10, beta=1.0) -> int:
             residual = self.dx.norm(petsc4py.typing.NormType.NORM_2)
             if i == 1:
                 self.residual_0 = residual
-            relative_residual = residual / self.residual_0
+            relative_residual = residual / max(self.residual_0, atol)
 
             logger.info(
                 f"Newton iteration {i}"