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diff --git a/tensorflow/g3doc/resources/glossary.md b/tensorflow/g3doc/resources/glossary.md new file mode 100644 index 0000000000..ab1fc4eb27 --- /dev/null +++ b/tensorflow/g3doc/resources/glossary.md @@ -0,0 +1,149 @@ +# Glossary + +**Broadcasting operation** + +An operation that uses [numpy-style broadcasting](http://docs.scipy.org/doc/numpy/user/basics.broadcasting.html) +to make the shapes of its tensor arguments compatible. + +**Device** + +A piece of hardware that can run computation and has its own address space, +like a GPU or CPU. + +**eval** + +A method of `Tensor` that returns the value of the `Tensor`, triggering any +graph computation required to determine the value. You may only call `eval()` +on a `Tensor` in a graph that has been launched in a session. + +**Feed** + +TensorFlow's mechanism for patching a tensor directly into any node in a graph +launched in a session. You apply feeds when you trigger the execution of a +graph, not when you build the graph. A feed temporarily replaces a node with a +tensor value. You supply feed data as an argument to a run() or eval() call +that initiates computation. After the run the feed disappears and the original +node definition remains. You usually designate specific nodes to be "feed" +nodes by using tf.placeholder() to create them. See +[Basic Usage](../get_started/basic_usage.md) for more information. + +**Fetch** + +TensorFlow's mechanism for retrieving tensors from a graph launched in a +session. You retrieve fetches when you trigger the execution of a graph, not +when you build the graph. To fetch the tensor value of a node or nodes, +execute the graph with a run() call on the Session object and pass a list of +names of nodes to retrieve. See [Basic Usage](../get_started/basic_usage.md) +for more information. + +**Graph** + +Describes a computation as a directed acyclic +graph. Nodes in the graph represent operations that must be +performed. Edges in the graph represent either data or control +dependencies. GraphDef is the proto used to describe a graph to the +system (it is the API), and consists of a collection of NodeDefs (see +below). A GraphDef may be converted to a (C++) Graph object which is +easier to operate on. + +**IndexedSlices** + +In the Python API, TensorFlow's representation of a tensor that is sparse +along only its first dimension. If the tensor is k-dimensional, an +IndexedSlices instance logically represents a collection of (k-1)-dimensional +slices along the tensor's first dimension. The indices of the slices are +stored concatenated into a single 1-dimensional vector, and the corresponding +slices are concatenated to form a single k-dimensional tensor. Use +SparseTensor if the sparsity is not restricted to the first dimension. + +**Node** + +An element of a graph. + +Describes how to invoke a specific Op as one node in a specific computation +Graph, including the values for any attrs needed to configure the Op. For Ops +that are polymorphic, the attrs include sufficient information to completely +determine the signature of the Node. See graph.proto for details. + +**Op (operation)** + +In the TensorFlow runtime: A type of computation such as 'add' or 'matmul' or +'concat'. You can add new ops to the runtime as described [how to add an +op](../how_tos/adding_an_op/index.md). + +In the Python API: A node in the graph. Ops are represented by instances of +the class [tf.Operation](../api_docs/python/framework.md#Operation). The +`type` property of an `Operation` indicates the run operation for the node, +such as 'add' or 'matmul'. + +**Quantization** + +A reduction of numerical precision. Quantization maps floating-point values +onto a smaller set of values, and is particular useful for improving the +efficiency of neural networks. See TensorFlow's [neural network +operations](../api_docs/python/nn.md?cl=head#quantized_avg_pool) for more +information about TensorFlow's quantization support. + +**Run** + +The action of executing ops in a launched graph. Requires that the graph be launched +in a Session. + +In the Python API: A method of the Session class: +[tf.Session.run](../api_docs/python/client.md#Session). You can pass tensors +to feed and fetch to the `run()` call. + +In the C++ API: A method of the [tensorflow::Session](../api_docs/cc/ClassSession.md). + +**Session** + +A runtime object representing a launched graph. Provides methods to execute +ops in the graph. + +In the Python API: [tf.Session](../api_docs/python/client.md#Session) + +In the C++ API: class used to launch a graph and run operations +[tensorflow::Session](../api_docs/cc/ClassSession.md). + +**Shape** + +The number of dimensions of a tensor and their sizes. + +In a launched graph: Property of the tensors that flow between nodes. Some ops +have strong requirements on the shape of their inputs and report errors at +runtime if these are not met. + +In the Python API: Attribute of a Python Tensor in the graph construction +API. During constructions the shape of tensors can be only partially known, or +even unknown. See +[tf.TensorShape](../api_docs/python/framework.md#TensorShape) + +In the C++ API: class used to represent the shape of tensors +[tensorflow::TensorShape](../api_docs/cc/ClassTensorShape.md). + +**SparseTensor** + +In the Python API, TensorFlow's representation of a tensor that is sparse in +arbitrary positions. A SparseTensor stores only the non-empty values along +with their indices, using a dictionary-of-keys format. In other words, if +there are m non-empty values, it maintains a length-m vector of values and +a matrix with m rows of indices. For efficiency, SparseTensor requires the +indices to be sorted along increasing dimension number, i.e. in row-major +order. Use IndexedSlices if the sparsity is only along the first dimension. + +**Tensor** + +A `Tensor` is a typed multi-dimensional array. For example, a 4-D +array of floating point numbers representing a mini-batch of images with +dimensions `[batch, height, width, channel]`. + +In a launched graph: Type of the data that flow between nodes. + +In the Python API: class used to represent the output and inputs of Ops added +to the graph [tf.Tensor](../api_docs/python/framework.md#Tensor). Instances of +this class do not hold data. + +In the C++ API: class used to represent tensors returned from a +[Session::Run()](../api_docs/cc/ClassSession.md) call +[tensorflow::Tensor](../api_docs/cc/ClassTensor.md). +Instances of this class hold data. |