Add tensor pages

Author: rangsimanketkaew

tensorflow_tensor.md

@@ -0,0 +1,90 @@
+# TensorFlow Tensor
+
+https://www.tensorflow.org/api_docs/cc/class/tensorflow/tensor
+
+## Create a tensor
+
+**Create a vector tensor**
+```cpp
+#include <tensorflow/core/public/session.h>
+#include <tensorflow/core/platform/env.h>
+
+using namespace std;
+using namespace tensorflow;
+
+int main(int argc, char* argv[]) {
+
+    Tensor a(DT_FLOAT, TensorShape({2}));
+    auto a_vec = a.vec<float>();
+    a_vec(0) = 1.0f;
+    a_vec(1) = 2.0f;
+
+    cout << "Vector tensor" << endl;
+
+    return 0;
+}
+```
+
+**Create a matrix tensor**
+```cpp
+#include <tensorflow/core/public/session.h>
+#include <tensorflow/core/platform/env.h>
+
+using namespace std;
+using namespace tensorflow;
+
+int main(int argc, char* argv[]) {
+
+    Tensor b(DT_FLOAT, TensorShape({2,2}));
+    auto b_mat = b.matrix<float>();
+    b_mat(0,0) = 1.0f;
+    b_mat(0,1) = 2.0f;
+    b_mat(1,0) = 3.0f;
+    b_mat(1,1) = 4.0f;
+
+    return 0;
+}
+```
+
+**Print tensor components**
+
+Method 1:
+```cpp
+...
+    cout << "First element: " << a_vec(0) << endl; // output: 1
+    // or
+    cout << "First element: " << b_mat(0) << endl; // output: 1
+...
+```
+
+Method 2: pointer
+```cpp
+...
+    // get pointer to memory for the tensor
+    float * p = b.vec<float>().data();
+    cout << typeid(p).name() << endl;
+    cout << p[0] << endl;
+    cout << p[1] << endl;
+    cout << p[2] << endl;
+    cout << p[3] << endl;
+...
+```
+
+**Print shape info**
+```cpp
+...
+    cout << b.shape().dims() << endl;
+    // output: 2
+...
+```
+
+## Convert vector to tensor
+
+**Use `std::copy`
+```cpp
+...
+    vector<float> myvec = {5,6,7};
+    Tensor a(DT_FLOAT, TensorShape({3}));
+    copy(myvec.begin(), myvec.end(), a.flat<float>().data() );
+...
+```