fixed stochastic laplace 1d

mlmc/src/problem/StochasticEllipticProblem.hpp

@@ -32,10 +32,10 @@ class StochasticLaplace1D : public StochasticEllipticProblem {
 public:
     StochasticLaplace1D() = default;
 
-    Scalar Solution(const Point &x) const override { return -x[0]; }
+    Scalar Solution(const Point &x) const override { return 1 - x[0]; }
 
     VectorField Flux(int, const Point &x) const override {
-        return VectorField(-1.0, 0.0);
+        return VectorField(1.0, 0.0);
     }
 
     Scalar Load(int, const Point &x) const override { return 0.0; }