use determinant

Base/Spin/SpinMatrix.h

@@ -57,7 +57,7 @@ public:
     complex_t operator()(int, int) const;
 
     complex_t trace() const;
-    complex_t determinant() const; // TODO use
+    complex_t determinant() const;
 
     bool allFinite() const;
 

Resample/Specular/ComputeFluxMagnetic.cpp

@@ -82,7 +82,7 @@ void calculateUpwards(std::vector<MatrixFlux>& coeff, const SliceStack& slices,
         // compute the rotation matrix
         SpinMatrix Si = mp + mm * coeff[i].m_R;
         SpinMatrix S = MakeSpinMatrix(Si(1, 1), -Si(0, 1), -Si(1, 0), Si(0, 0));
-        const complex_t norm = S(0, 0) * S(1, 1) - S(0, 1) * S(1, 0);
+        const complex_t norm = S.determinant();
         S = S * delta;
 
         // store the rotation matrix and normalization constant in order to rotate
@@ -231,7 +231,7 @@ SpinMatrix Compute::SpecularMagnetic::topLayerR(const SliceStack& slices,
         // compute the rotation matrix
         SpinMatrix Si = mp + mm * c_i1.m_R;
         SpinMatrix S = MakeSpinMatrix(Si(1, 1), -Si(0, 1), -Si(1, 0), Si(0, 0));
-        const complex_t norm = S(0, 0) * S(1, 1) - S(0, 1) * S(1, 0);
+        const complex_t norm = S.determinant();
         S = S * delta;
         S /= norm;