Merge branch '210-offset_add-is-not-behaving-as-expected-2' into 'master'

Resolve "offset_add is not behaving as expected"

Closes #210

See merge request !1

src/unitTests/tensor.cxx

@@ -287,5 +287,22 @@ static misc::UnitTest tensor_sparse_dense("Tensor", "Sparse_Dense_Conversions",
 	TEST(R.representation == Tensor::Representation::Dense);
 });
 
+static misc::UnitTest tensor_offset_add("Tensor", "Check_Offset_Add", [](){
+	auto first  = xerus::Tensor::dirac({1,1,1,1},0);
+	auto second  = xerus::Tensor::dirac({2,2,1,1},0);
+	second[3] = 4;
+	second[1] = 2;
+	second[2] = 3;
+	std::unique_ptr<Tensor> comb(new Tensor({3,3,2,2}));
+	comb->offset_add(first, std::vector<size_t>({0,0,0,0}));
+	comb->offset_add(second, std::vector<size_t>({1,1,1,1}));
+	TEST(((*comb)[0] - 1) * ((*comb)[0] - 1) <= 0.01);
+	TEST(((*comb)[19] - 1) * ((*comb)[19] - 1) <= 0.01);
+	TEST(((*comb)[23] - 2) * ((*comb)[23] - 2) <= 0.01);
+	TEST(((*comb)[31] - 3) * ((*comb)[31] - 3) <= 0.01);
+	TEST(((*comb)[35] - 4) * ((*comb)[35] - 4) <= 0.01);
+	TEST(((*comb)[1]) * ((*comb)[1]) <= 0.01);
+	TEST(((*comb)[2]) * ((*comb)[2]) <= 0.01);
 
+});
 

src/xerus/tensor.cpp

@@ -998,10 +998,10 @@ namespace xerus {
 				inPosition += blockSize;
 				outPosition += stepSizes[index];
 				while(i%multStep == 0) {
-					outPosition -= dimensions[index]*stepSizes[index]; // "reset" current index to 0
+					outPosition -= _other.dimensions[index]*stepSizes[index]; // "reset" current index to 0
 					--index;							// Advance to next index
 					outPosition += stepSizes[index];	// increase next index
-					multStep *= dimensions[index];		// next stepSize
+					multStep *= _other.dimensions[index];		// next stepSize
 				}
 				
 				misc::add_scaled(outPosition, _other.factor, inPosition, blockSize);