Allowed tensor contraction operation with an empty array of dimension pairs, which performs a tensor product.

1 files changed, 16 insertions, 14 deletions

diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorContraction.h b/unsupported/Eigen/CXX11/src/Tensor/TensorContraction.h
index 59ae4a2d0..85ae9dd6a 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorContraction.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorContraction.h
@@ -66,7 +66,7 @@ class BaseTensorContractionMapper {
     const bool left = (side == Lhs);
     Index nocontract_val = left ? row : col;
     Index linidx = 0;
-    for (int i = array_size<nocontract_t>::value - 1; i > 0; i--) {
+    for (int i = static_cast<int>(array_size<nocontract_t>::value) - 1; i > 0; i--) {
       const Index idx = nocontract_val / m_ij_strides[i];
       linidx += idx * m_nocontract_strides[i];
       nocontract_val -= idx * m_ij_strides[i];
@@ -81,17 +81,19 @@ class BaseTensorContractionMapper {
     }
 
     Index contract_val = left ? col : row;
-    for (int i = array_size<contract_t>::value - 1; i > 0; i--) {
+    for (int i = static_cast<int>(array_size<contract_t>::value) - 1; i > 0; i--) {
       const Index idx = contract_val / m_k_strides[i];
       linidx += idx * m_contract_strides[i];
       contract_val -= idx * m_k_strides[i];
     }
-    EIGEN_STATIC_ASSERT(array_size<contract_t>::value > 0, YOU_MADE_A_PROGRAMMING_MISTAKE);
-    if (side == Rhs && inner_dim_contiguous) {
-      eigen_assert(m_contract_strides[0] == 1);
-      linidx += contract_val;
-    } else {
-      linidx += contract_val * m_contract_strides[0];
+
+    if(array_size<contract_t>::value > 0) {
+        if (side == Rhs && inner_dim_contiguous) {
+            eigen_assert(m_contract_strides[0] == 1);
+            linidx += contract_val;
+        } else {
+            linidx += contract_val * m_contract_strides[0];
+        }
     }
 
     return linidx;
@@ -102,7 +104,7 @@ class BaseTensorContractionMapper {
     const bool left = (side == Lhs);
     Index nocontract_val[2] = {left ? row : col, left ? row + distance : col};
     Index linidx[2] = {0, 0};
-    for (int i = array_size<nocontract_t>::value - 1; i > 0; i--) {
+    for (int i = static_cast<int>(array_size<nocontract_t>::value) - 1; i > 0; i--) {
       const Index idx0 = nocontract_val[0] / m_ij_strides[i];
       const Index idx1 = nocontract_val[1] / m_ij_strides[i];
       linidx[0] += idx0 * m_nocontract_strides[i];
@@ -122,7 +124,7 @@ class BaseTensorContractionMapper {
     }
 
     Index contract_val[2] = {left ? col : row, left ? col : row + distance};
-    for (int i = array_size<contract_t>::value - 1; i > 0; i--) {
+    for (int i = static_cast<int>(array_size<contract_t>::value) - 1; i > 0; i--) {
       const Index idx0 = contract_val[0] / m_k_strides[i];
       const Index idx1 = contract_val[1] / m_k_strides[i];
       linidx[0] += idx0 * m_contract_strides[i];
@@ -130,7 +132,7 @@ class BaseTensorContractionMapper {
       contract_val[0] -= idx0 * m_k_strides[i];
       contract_val[1] -= idx1 * m_k_strides[i];
     }
-    EIGEN_STATIC_ASSERT(array_size<contract_t>::value > 0, YOU_MADE_A_PROGRAMMING_MISTAKE);
+
     if (side == Rhs && inner_dim_contiguous) {
       eigen_assert(m_contract_strides[0] == 1);
       linidx[0] += contract_val[0];
@@ -509,8 +511,6 @@ struct TensorContractionEvaluatorBase
 			   static_cast<int>(TensorEvaluator<RightArgType, Device>::Layout)),
                         YOU_MADE_A_PROGRAMMING_MISTAKE);
 
-    eigen_assert((internal::array_size<contract_t>::value > 0) && "Must contract on some indices");
-
 
     DSizes<Index, LDims> eval_left_dims;
     DSizes<Index, RDims> eval_right_dims;
@@ -558,7 +558,9 @@ struct TensorContractionEvaluatorBase
 
     m_i_strides[0] = 1;
     m_j_strides[0] = 1;
-    m_k_strides[0] = 1;
+    if(ContractDims) {
+        m_k_strides[0] = 1;
+    }
 
     m_i_size = 1;
     m_j_size = 1;