Modify default ncc and entry cutoffs to more performant values

hg hash: 1e1bc32f41bc325d47e92f576c18efa1ad2a4057

dedalus/core/problems.py

@@ -72,9 +72,11 @@ class ProblemBase:
     variables : list of str
         List of variable names, e.g. ['u', 'v', 'w']
     ncc_cutoff : float, optional
-        Mode amplitude cutoff for LHS NCC expansions (default: 1e-10)
+        Mode amplitude cutoff for LHS NCC expansions (default: 1e-6)
     max_ncc_terms : int, optional
         Maximum terms to include in LHS NCC expansions (default: None (no limit))
+    entry_cutoff : float, optional
+        Matrix entry cutoff to avoid fill-in from cancellation errors (default: 1e-12)
 
     Attributes
     ----------
@@ -100,7 +102,7 @@ class ProblemBase:
 
     """
 
-    def __init__(self, domain, variables, ncc_cutoff=1e-10, max_ncc_terms=None, entry_cutoff=0):
+    def __init__(self, domain, variables, ncc_cutoff=1e-6, max_ncc_terms=None, entry_cutoff=1e-12):
         self.domain = domain
         self.variables = variables
         self.nvars = len(variables)

examples/bvp/1d_lane_emden/lane_emden.py

@@ -42,9 +42,9 @@
 
 # Parameters
 Nx = 128
-n = 3.25
-ncc_cutoff = 1e-4
-tolerance = 1e-8
+n = 3.0
+ncc_cutoff = 1e-6
+tolerance = 1e-12
 
 # Build domain
 x_basis = de.Chebyshev('x', Nx, interval=(0, 1), dealias=2)