diff --git a/lib/LatAnalyze/Physics/DataFilter.cpp b/lib/LatAnalyze/Physics/DataFilter.cpp
index acded7a..caffa90 100644
--- a/lib/LatAnalyze/Physics/DataFilter.cpp
+++ b/lib/LatAnalyze/Physics/DataFilter.cpp
@@ -66,18 +66,18 @@ void DataFilter::operator()(DMat &out, const DMat &in)
  ******************************************************************************/
 // constructor ////////////////////////////////////////////////////////////////
 LaplaceDataFilter::LaplaceDataFilter(const bool downsample)
-: DataFilter({1., -2. , 1.}, downsample)
+: DataFilter({-1., 2. , -1.}, downsample)
 {}
 
 // filtering //////////////////////////////////////////////////////////////////
 void LaplaceDataFilter::operator()(DVec &out, const DVec &in, const double lambda)
 {
-    filter_[1] = -2. - lambda;
+    filter_[1] = 2. + Math::pow<2>(lambda);
     DataFilter::operator()(out, in);
 }
 
 void LaplaceDataFilter::operator()(DMat &out, const DMat &in, const double lambda)
 {
-    filter_[1] = -2. - lambda;
+    filter_[1] = 2. + Math::pow<2>(lambda);
     DataFilter::operator()(out, in);
 }
diff --git a/lib/LatAnalyze/Physics/DataFilter.hpp b/lib/LatAnalyze/Physics/DataFilter.hpp
index 85561ad..2195dda 100644
--- a/lib/LatAnalyze/Physics/DataFilter.hpp
+++ b/lib/LatAnalyze/Physics/DataFilter.hpp
@@ -70,7 +70,7 @@ public:
     template <typename MatType, Index o>
     double optimiseFunction(const StatArray<MatType, o> &data, 
                             ObjectiveFunction<MatType, o> &fn,
-                            Minimizer &min, const unsigned int nPass = 3);
+                            Minimizer &min);
 };
 
 /******************************************************************************
@@ -104,8 +104,7 @@ void LaplaceDataFilter::operator()(StatArray<MatType, o> &out,
 template <typename MatType, Index o>
 double LaplaceDataFilter::optimiseFunction(const StatArray<MatType, o> &data, 
                                            ObjectiveFunction<MatType, o> &fn, 
-                                           Minimizer &min,
-                                           const unsigned int nPass)
+                                           Minimizer &min)
 {
     StatArray<MatType, o> fdata(data.size());
     DVec init(1);