Fix source term in nonlinear tests

test/nonlinear/nonlinear.mini

@@ -11,4 +11,4 @@ reference = nonlinear_ref
 extension = vtu
 
 [formcompiler]
-compare_l2errorsquared = 6e-4
\ No newline at end of file
+compare_l2errorsquared = 1e-6
\ No newline at end of file

test/nonlinear/nonlinear.ufl

 cell = "triangle"
 x = SpatialCoordinate(cell)
 
-f = -4.
+mu = 2.
+f = -4. + mu * (x[0]*x[0] + x[1]*x[1])* (x[0]*x[0] + x[1]*x[1])
 g = x[0]*x[0] + x[1]*x[1]
 
 V = FiniteElement("CG", cell, 1)
 u = TrialFunction(V)
 v = TestFunction(V)
 
-r = (inner(grad(u), grad(v)) + u*u*v - f*v)*dx
+r = (inner(grad(u), grad(v)) + mu*u*u*v - f*v)*dx
 
 exact_solution = g
 interpolate_expression = g

test/nonlinear/nonlinear_dg.mini

@@ -11,4 +11,4 @@ reference = nonlinear_dg
 extension = vtu
 
 [formcompiler]
-compare_l2errorsquared = 6e-4
+compare_l2errorsquared = 1e-7

test/nonlinear/nonlinear_dg.ufl

 cell = "triangle"
 degree = 1
 dim = 2
-
 x = SpatialCoordinate(cell)
-f = -4.
+
+mu = 2.
+f = -4. + mu * (x[0]*x[0] + x[1]*x[1])* (x[0]*x[0] + x[1]*x[1])
 g = x[0]*x[0] + x[1]*x[1]
 
 V = FiniteElement("DG", cell, degree)
@@ -14,7 +15,7 @@ v = TestFunction(V)
 n = FacetNormal(cell)('+')
 
 def q(u):
-    return u*u
+    return mu*u*u
 
 # penalty factor
 alpha = 1.0