add checks

scripts/run_experiments.jl

@@ -73,6 +73,9 @@ end
 
 function L1L2TVState(mesh, m; T, tdata, S,
 	alpha1, alpha2, beta, lambda, gamma1, gamma2)
+    alpha2 > 0 || beta > 0 ||
+        throw(ArgumentError("operator B is singular with these parameters"))
+
     d = ndims_domain(mesh)
 
     Vest = FeSpace(mesh, DP0(), (1,))
@@ -106,6 +109,9 @@ end
 
 function OptFlowState(mesh;
 	alpha1, alpha2, beta, lambda, gamma1, gamma2)
+    alpha2 > 0 || beta > 0 ||
+        throw(ArgumentError("operator B is singular with these parameters"))
+
     d = ndims_domain(mesh)
     m = 2