Avoid warnings about comparsion of int/unsigned int

[[Imported from SVN: r12628]]

dune/contact/assemblers/nbodyassembler.cc

@@ -571,14 +571,14 @@ assembleRightHandSide(const std::vector<DiscFuncType>& rhs,
 
     int idx = 0;
 
-    for (int i=0; i<rhs.size(); i++) {
+    for (size_t i=0; i<rhs.size(); i++) {
 
-        for (int j=0; j<rhs[i].size(); j++)
+        for (size_t j=0; j<rhs[i].size(); j++)
             untransformedTotalRhs[idx++] = rhs[i][j];
 
     }
 
-    if (this->BT_.M() != idx)
+    if ((int) this->BT_.M() != idx)
         DUNE_THROW(Dune::Exception, "assembleRightHandSide: vector size and matrix size don't match!");
 
     // Transform the basis of the ansatz space
@@ -738,7 +738,7 @@ computeTransformationMatrix()
     MatrixIndexSet indicesBT(nRows, nCols); 
         
     // BT_ is the identity plus some off-diagonal elements
-    for (int i=0; i<indicesBT.rows(); i++)
+    for (size_t i=0; i<indicesBT.rows(); i++)
         indicesBT.add(i,i);
 
     // Enter all the off-diagonal entries