diff --git a/lib/Core/Math.cpp b/lib/Core/Math.cpp
index 5278412..16ab66d 100644
--- a/lib/Core/Math.cpp
+++ b/lib/Core/Math.cpp
@@ -18,6 +18,7 @@
  */
 
 #include <LatAnalyze/Core/Math.hpp>
+#include <LatAnalyze/Numerical/GslFFT.hpp>
 #include <LatAnalyze/includes.hpp>
 #include <gsl/gsl_cdf.h>
 
@@ -48,16 +49,42 @@ DMat MATH_NAMESPACE::corrToVar(const DMat &corr, const DVec &varDiag)
     return res;
 }
 
-double MATH_NAMESPACE::svdDynamicRange(const DMat &mat)
+double MATH_NAMESPACE::conditionNumber(const DMat &mat)
 {
     DVec s = mat.singularValues();
 
     return s.maxCoeff()/s.minCoeff();
 }
 
-double MATH_NAMESPACE::svdDynamicRangeDb(const DMat &mat)
+double MATH_NAMESPACE::cdr(const DMat &mat)
 {
-    return 10.*log10(svdDynamicRange(mat));
+    return 10.*log10(conditionNumber(mat));
+}
+
+template <typename FFT>
+double nsdr(const DMat &m)
+{
+    Index  n = m.rows();
+    FFT    fft(n);
+    CMat   buf(n, 1);
+
+    FOR_VEC(buf, i)
+    {
+        buf(i) = 0.;
+        for (Index j = 0; j < n; ++j)
+        {
+            buf(i) += m(j, (i+j) % n);
+        }
+        buf(i) /= n;
+    }
+    fft(buf, FFT::Forward);
+
+    return 10.*log10(buf.real().maxCoeff()/buf.real().minCoeff());
+}
+
+double MATH_NAMESPACE::nsdr(const DMat &mat)
+{
+    return ::nsdr<GslFFT>(mat);
 }
 
 /******************************************************************************
diff --git a/lib/Core/Math.hpp b/lib/Core/Math.hpp
index 0ece91a..7ad4ad1 100644
--- a/lib/Core/Math.hpp
+++ b/lib/Core/Math.hpp
@@ -73,8 +73,9 @@ namespace MATH_NAMESPACE
     DMat corrToVar(const DMat &corr, const DVec &varDiag);
 
     // matrix SVD dynamic range
-    double svdDynamicRange(const DMat &mat);
-    double svdDynamicRangeDb(const DMat &mat);
+    double conditionNumber(const DMat &mat);
+    double cdr(const DMat &mat);
+    double nsdr(const DMat &mat);
     
     // Constants
     constexpr double pi  = 3.1415926535897932384626433832795028841970;
diff --git a/lib/Statistics/XYSampleData.cpp b/lib/Statistics/XYSampleData.cpp
index 0676564..8b5e0d9 100644
--- a/lib/Statistics/XYSampleData.cpp
+++ b/lib/Statistics/XYSampleData.cpp
@@ -343,7 +343,7 @@ SampleFitResult XYSampleData::fit(std::vector<Minimizer *> &minimizer,
     result.nPar_       = sampleResult.getNPar();
     result.nDof_       = sampleResult.nDof_;
     result.parName_    = sampleResult.parName_;
-    result.corrRangeDb_ = Math::svdDynamicRangeDb(getFitCorrMat());
+    result.corrRangeDb_ = Math::cdr(getFitCorrMat());
     
     return result;
 }
diff --git a/lib/Statistics/XYStatData.cpp b/lib/Statistics/XYStatData.cpp
index 690a3a6..b83397f 100644
--- a/lib/Statistics/XYStatData.cpp
+++ b/lib/Statistics/XYStatData.cpp
@@ -358,7 +358,7 @@ FitResult XYStatData::fit(vector<Minimizer *> &minimizer, const DVec &init,
         result    = (*m)(chi2);
         totalInit = result;
     }
-    result.corrRangeDb_ = Math::svdDynamicRangeDb(getFitCorrMat());
+    result.corrRangeDb_ = Math::cdr(getFitCorrMat());
     result.chi2_       = chi2(result);
     result.nPar_       = nPar;
     result.nDof_       = layout.totalYSize - nPar;
diff --git a/utils/sample-plot-corr.cpp b/utils/sample-plot-corr.cpp
index c900dc0..34e4d98 100644
--- a/utils/sample-plot-corr.cpp
+++ b/utils/sample-plot-corr.cpp
@@ -68,7 +68,7 @@ int main(int argc, char *argv[])
     var    = sample.varianceMatrix();
     corr   = sample.correlationMatrix();
 
-    cout << "dynamic range " << Math::svdDynamicRangeDb(corr) << " dB" << endl;
+    cout << "dynamic range " << Math::cdr(corr) << " dB" << endl;
     p << PlotCorrMatrix(corr);
     p.display();
     if (!outVarName.empty())