`class tf.Variable`

See the Variables How To for a high level overview.

A variable maintains state in the graph across calls to `run()`

. You add a
variable to the graph by constructing an instance of the class `Variable`

.

The `Variable()`

constructor requires an initial value for the variable,
which can be a `Tensor`

of any type and shape. The initial value defines the
type and shape of the variable. After construction, the type and shape of
the variable are fixed. The value can be changed using one of the assign
methods.

If you want to change the shape of a variable later you have to use an
`assign`

Op with `validate_shape=False`

.

Just like any `Tensor`

, variables created with `Variable()`

can be used as
inputs for other Ops in the graph. Additionally, all the operators
overloaded for the `Tensor`

class are carried over to variables, so you can
also add nodes to the graph by just doing arithmetic on variables.

```
import tensorflow as tf
# Create a variable.
w = tf.Variable(<initial-value>, name=<optional-name>)
# Use the variable in the graph like any Tensor.
y = tf.matmul(w, ...another variable or tensor...)
# The overloaded operators are available too.
z = tf.sigmoid(w + y)
# Assign a new value to the variable with `assign()` or a related method.
w.assign(w + 1.0)
w.assign_add(1.0)
```

When you launch the graph, variables have to be explicitly initialized before
you can run Ops that use their value. You can initialize a variable by
running its *initializer op*, restoring the variable from a save file, or
simply running an `assign`

Op that assigns a value to the variable. In fact,
the variable *initializer op* is just an `assign`

Op that assigns the
variable's initial value to the variable itself.

```
# Launch the graph in a session.
with tf.Session() as sess:
# Run the variable initializer.
sess.run(w.initializer)
# ...you now can run ops that use the value of 'w'...
```

The most common initialization pattern is to use the convenience function
`initialize_all_variables()`

to add an Op to the graph that initializes
all the variables. You then run that Op after launching the graph.

```
# Add an Op to initialize all variables.
init_op = tf.initialize_all_variables()
# Launch the graph in a session.
with tf.Session() as sess:
# Run the Op that initializes all variables.
sess.run(init_op)
# ...you can now run any Op that uses variable values...
```

If you need to create a variable with an initial value dependent on another
variable, use the other variable's `initialized_value()`

. This ensures that
variables are initialized in the right order.

All variables are automatically collected in the graph where they are
created. By default, the constructor adds the new variable to the graph
collection `GraphKeys.VARIABLES`

. The convenience function
`all_variables()`

returns the contents of that collection.

When building a machine learning model it is often convenient to distinguish
between variables holding the trainable model parameters and other variables
such as a `global step`

variable used to count training steps. To make this
easier, the variable constructor supports a `trainable=<bool>`

parameter. If
`True`

, the new variable is also added to the graph collection
`GraphKeys.TRAINABLE_VARIABLES`

. The convenience function
`trainable_variables()`

returns the contents of this collection. The
various `Optimizer`

classes use this collection as the default list of
variables to optimize.

Creating a variable.

`tf.Variable.__init__(initial_value=None, trainable=True, collections=None, validate_shape=True, caching_device=None, name=None, variable_def=None, dtype=None)`

{:#Variable.**init**}

Creates a new variable with value `initial_value`

.

The new variable is added to the graph collections listed in `collections`

,
which defaults to `[GraphKeys.VARIABLES]`

.

If `trainable`

is `True`

the variable is also added to the graph collection
`GraphKeys.TRAINABLE_VARIABLES`

.

This constructor creates both a `variable`

Op and an `assign`

Op to set the
variable to its initial value.

##### Args:

: A`initial_value`

`Tensor`

, or Python object convertible to a`Tensor`

, which is the initial value for the Variable. The initial value must have a shape specified unless`validate_shape`

is set to False. Can also be a callable with no argument that returns the initial value when called. In that case,`dtype`

must be specified. (Note that initializer functions from init_ops.py must first be bound to a shape before being used here.): If`trainable`

`True`

, the default, also adds the variable to the graph collection`GraphKeys.TRAINABLE_VARIABLES`

. This collection is used as the default list of variables to use by the`Optimizer`

classes.: List of graph collections keys. The new variable is added to these collections. Defaults to`collections`

`[GraphKeys.VARIABLES]`

.: If`validate_shape`

`False`

, allows the variable to be initialized with a value of unknown shape. If`True`

, the default, the shape of`initial_value`

must be known.: Optional device string describing where the Variable should be cached for reading. Defaults to the Variable's device. If not`caching_device`

`None`

, caches on another device. Typical use is to cache on the device where the Ops using the Variable reside, to deduplicate copying through`Switch`

and other conditional statements.: Optional name for the variable. Defaults to`name`

`'Variable'`

and gets uniquified automatically.:`variable_def`

`VariableDef`

protocol buffer. If not`None`

, recreates the Variable object with its contents.`variable_def`

and the other arguments are mutually exclusive.: If set, initial_value will be converted to the given type. If`dtype`

`None`

, either the datatype will be kept (if`initial_value`

is a Tensor), or`convert_to_tensor`

will decide.

##### Raises:

: If both`ValueError`

`variable_def`

and initial_value are specified.: If the initial value is not specified, or does not have a shape and`ValueError`

`validate_shape`

is`True`

.

`tf.Variable.initialized_value()`

Returns the value of the initialized variable.

You should use this instead of the variable itself to initialize another variable with a value that depends on the value of this variable.

```
# Initialize 'v' with a random tensor.
v = tf.Variable(tf.truncated_normal([10, 40]))
# Use `initialized_value` to guarantee that `v` has been
# initialized before its value is used to initialize `w`.
# The random values are picked only once.
w = tf.Variable(v.initialized_value() * 2.0)
```

##### Returns:

A `Tensor`

holding the value of this variable after its initializer
has run.

Changing a variable value.

`tf.Variable.assign(value, use_locking=False)`

Assigns a new value to the variable.

This is essentially a shortcut for `assign(self, value)`

.

##### Args:

: A`value`

`Tensor`

. The new value for this variable.: If`use_locking`

`True`

, use locking during the assignment.

##### Returns:

A `Tensor`

that will hold the new value of this variable after
the assignment has completed.

`tf.Variable.assign_add(delta, use_locking=False)`

Adds a value to this variable.

This is essentially a shortcut for `assign_add(self, delta)`

.

##### Args:

: A`delta`

`Tensor`

. The value to add to this variable.: If`use_locking`

`True`

, use locking during the operation.

##### Returns:

A `Tensor`

that will hold the new value of this variable after
the addition has completed.

`tf.Variable.assign_sub(delta, use_locking=False)`

Subtracts a value from this variable.

This is essentially a shortcut for `assign_sub(self, delta)`

.

##### Args:

: A`delta`

`Tensor`

. The value to subtract from this variable.: If`use_locking`

`True`

, use locking during the operation.

##### Returns:

A `Tensor`

that will hold the new value of this variable after
the subtraction has completed.

`tf.Variable.scatter_sub(sparse_delta, use_locking=False)`

Subtracts `IndexedSlices`

from this variable.

This is essentially a shortcut for ```
scatter_sub(self, sparse_delta.indices,
sparse_delta.values)
```

.

##### Args:

:`sparse_delta`

`IndexedSlices`

to be subtracted from this variable.: If`use_locking`

`True`

, use locking during the operation.

##### Returns:

A `Tensor`

that will hold the new value of this variable after
the scattered subtraction has completed.

##### Raises:

: if`ValueError`

`sparse_delta`

is not an`IndexedSlices`

.

`tf.Variable.count_up_to(limit)`

Increments this variable until it reaches `limit`

.

When that Op is run it tries to increment the variable by `1`

. If
incrementing the variable would bring it above `limit`

then the Op raises
the exception `OutOfRangeError`

.

If no error is raised, the Op outputs the value of the variable before the increment.

This is essentially a shortcut for `count_up_to(self, limit)`

.

##### Args:

: value at which incrementing the variable raises an error.`limit`

##### Returns:

A `Tensor`

that will hold the variable value before the increment. If no
other Op modifies this variable, the values produced will all be
distinct.

`tf.Variable.eval(session=None)`

In a session, computes and returns the value of this variable.

This is not a graph construction method, it does not add ops to the graph.

This convenience method requires a session where the graph containing this variable has been launched. If no session is passed, the default session is used. See the Session class for more information on launching a graph and on sessions.

```
v = tf.Variable([1, 2])
init = tf.initialize_all_variables()
with tf.Session() as sess:
sess.run(init)
# Usage passing the session explicitly.
print(v.eval(sess))
# Usage with the default session. The 'with' block
# above makes 'sess' the default session.
print(v.eval())
```

##### Args:

: The session to use to evaluate this variable. If none, the default session is used.`session`

##### Returns:

A numpy `ndarray`

with a copy of the value of this variable.

Properties.

`tf.Variable.name`

The name of this variable.

`tf.Variable.dtype`

The `DType`

of this variable.

`tf.Variable.get_shape()`

The `TensorShape`

of this variable.

##### Returns:

A `TensorShape`

.

`tf.Variable.device`

The device of this variable.

`tf.Variable.initializer`

The initializer operation for this variable.

`tf.Variable.graph`

The `Graph`

of this variable.

`tf.Variable.op`

The `Operation`

of this variable.

#### Other Methods

`tf.Variable.__abs__(a, *args)`

{:#Variable.**abs**}

Computes the absolute value of a tensor.

Given a tensor of real numbers `x`

, this operation returns a tensor
containing the absolute value of each element in `x`

. For example, if x is
an input element and y is an output element, this operation computes
\(y = |x|\).

See `tf.complex_abs()`

to compute the absolute value of a complex
number.

##### Args:

: A`x`

`Tensor`

or`SparseTensor`

of type`float32`

,`float64`

,`int32`

, or`int64`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

or `SparseTensor`

the same size and type as `x`

with absolute
values.

`tf.Variable.__add__(a, *args)`

{:#Variable.**add**}

Returns x + y element-wise.

*NOTE*: `Add`

supports broadcasting. `AddN`

does not. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

. Must be one of the following types:`half`

,`float32`

,`float64`

,`uint8`

,`int8`

,`int16`

,`int32`

,`int64`

,`complex64`

,`complex128`

,`string`

.: A`y`

`Tensor`

. Must have the same type as`x`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

. Has the same type as `x`

.

`tf.Variable.__and__(a, *args)`

{:#Variable.**and**}

Returns the truth value of x AND y element-wise.

*NOTE*: `LogicalAnd`

supports broadcasting. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

of type`bool`

.: A`y`

`Tensor`

of type`bool`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

of type `bool`

.

`tf.Variable.__div__(a, *args)`

{:#Variable.**div**}

Returns x / y element-wise.

*NOTE*: `Div`

supports broadcasting. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

. Must be one of the following types:`half`

,`float32`

,`float64`

,`uint8`

,`int8`

,`uint16`

,`int16`

,`int32`

,`int64`

,`complex64`

,`complex128`

.: A`y`

`Tensor`

. Must have the same type as`x`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

. Has the same type as `x`

.

`tf.Variable.__floordiv__(a, *args)`

{:#Variable.**floordiv**}

Divides `x / y`

elementwise, rounding down for floating point.

The same as `tf.div(x,y)`

for integers, but uses `tf.floor(tf.div(x,y))`

for
floating point arguments so that the result is always an integer (though
possibly an integer represented as floating point). This op is generated by
`x // y`

floor division in Python 3 and in Python 2.7 with
`from __future__ import division`

.

Note that for efficiency, `floordiv`

uses C semantics for negative numbers
(unlike Python and Numpy).

`x`

and `y`

must have the same type, and the result will have the same type
as well.

##### Args:

:`x`

`Tensor`

numerator of real numeric type.:`y`

`Tensor`

denominator of real numeric type.: A name for the operation (optional).`name`

##### Returns:

`x / y`

rounded down (except possibly towards zero for negative integers).

##### Raises:

: If the inputs are complex.`TypeError`

`tf.Variable.__ge__(a, *args)`

{:#Variable.**ge**}

Returns the truth value of (x >= y) element-wise.

*NOTE*: `GreaterEqual`

supports broadcasting. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

. Must be one of the following types:`float32`

,`float64`

,`int32`

,`int64`

,`uint8`

,`int16`

,`int8`

,`uint16`

,`half`

.: A`y`

`Tensor`

. Must have the same type as`x`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

of type `bool`

.

`tf.Variable.__getitem__(var, slice_spec)`

{:#Variable.**getitem**}

Creates a slice helper object given a variable.

This allows creating a sub-tensor from part of the current contents
of a variable.
See
`Tensor.__getitem__`

for detailed examples of slicing.

This function in addition also allows assignment to a sliced range.
This is similar to `__setitem__`

functionality in Python. However,
the syntax is different so that the user can capture the assignment
operation for grouping or passing to `sess.run()`

.
For example,

```
import tensorflow as tf
A = tf.Variable([[1,2,3], [4,5,6], [7,8,9]], dtype=tf.float32)
with tf.Session() as sess:
sess.run(tf.initialize_all_variables())
print sess.run(A[:2, :2]) # => [[1,2], [4,5]]
op = A[:2,:2].assign(22. * tf.ones((2, 2)))
print sess.run(op) # => [[22, 22, 3], [22, 22, 6], [7,8,9]]
```

Note that assignments currently do not support NumPy broadcasting semantics.

##### Args:

: An`var`

`ops.Variable`

object.: The arguments to`slice_spec`

`Tensor.__getitem__`

.

##### Returns:

The appropriate slice of "tensor", based on "slice_spec".
As an operator. The operator also has a `assign()`

method
that can be used to generate an assignment operator.

##### Raises:

: If a slice range is negative size.`ValueError`

: If the slice indices aren't int, slice, or Ellipsis.`TypeError`

`tf.Variable.__gt__(a, *args)`

{:#Variable.**gt**}

Returns the truth value of (x > y) element-wise.

*NOTE*: `Greater`

supports broadcasting. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

. Must be one of the following types:`float32`

,`float64`

,`int32`

,`int64`

,`uint8`

,`int16`

,`int8`

,`uint16`

,`half`

.: A`y`

`Tensor`

. Must have the same type as`x`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

of type `bool`

.

`tf.Variable.__invert__(a, *args)`

{:#Variable.**invert**}

Returns the truth value of NOT x element-wise.

##### Args:

: A`x`

`Tensor`

of type`bool`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

of type `bool`

.

`tf.Variable.__iter__()`

{:#Variable.**iter**}

Dummy method to prevent iteration. Do not call.

NOTE(mrry): If we register **getitem** as an overloaded operator,
Python will valiantly attempt to iterate over the variable's Tensor from 0
to infinity. Declaring this method prevents this unintended behavior.

##### Raises:

: when invoked.`TypeError`

`tf.Variable.__le__(a, *args)`

{:#Variable.**le**}

Returns the truth value of (x <= y) element-wise.

*NOTE*: `LessEqual`

supports broadcasting. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

. Must be one of the following types:`float32`

,`float64`

,`int32`

,`int64`

,`uint8`

,`int16`

,`int8`

,`uint16`

,`half`

.: A`y`

`Tensor`

. Must have the same type as`x`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

of type `bool`

.

`tf.Variable.__lt__(a, *args)`

{:#Variable.**lt**}

Returns the truth value of (x < y) element-wise.

*NOTE*: `Less`

supports broadcasting. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

. Must be one of the following types:`float32`

,`float64`

,`int32`

,`int64`

,`uint8`

,`int16`

,`int8`

,`uint16`

,`half`

.: A`y`

`Tensor`

. Must have the same type as`x`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

of type `bool`

.

`tf.Variable.__mod__(a, *args)`

{:#Variable.**mod**}

Returns element-wise remainder of division.

*NOTE*: `Mod`

supports broadcasting. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

. Must be one of the following types:`int32`

,`int64`

,`float32`

,`float64`

.: A`y`

`Tensor`

. Must have the same type as`x`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

. Has the same type as `x`

.

`tf.Variable.__mul__(a, *args)`

{:#Variable.**mul**}

Dispatches cwise mul for "Dense*Dense" and "Dense*Sparse".

`tf.Variable.__neg__(a, *args)`

{:#Variable.**neg**}

Computes numerical negative value element-wise.

I.e., \(y = -x\).

##### Args:

: A`x`

`Tensor`

. Must be one of the following types:`half`

,`float32`

,`float64`

,`int32`

,`int64`

,`complex64`

,`complex128`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

. Has the same type as `x`

.

`tf.Variable.__or__(a, *args)`

{:#Variable.**or**}

Returns the truth value of x OR y element-wise.

*NOTE*: `LogicalOr`

supports broadcasting. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

of type`bool`

.: A`y`

`Tensor`

of type`bool`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

of type `bool`

.

`tf.Variable.__pow__(a, *args)`

{:#Variable.**pow**}

Computes the power of one value to another.

Given a tensor `x`

and a tensor `y`

, this operation computes \(x^y\) for
corresponding elements in `x`

and `y`

. For example:

```
# tensor 'x' is [[2, 2], [3, 3]]
# tensor 'y' is [[8, 16], [2, 3]]
tf.pow(x, y) ==> [[256, 65536], [9, 27]]
```

##### Args:

: A`x`

`Tensor`

of type`float32`

,`float64`

,`int32`

,`int64`

,`complex64`

, or`complex128`

.: A`y`

`Tensor`

of type`float32`

,`float64`

,`int32`

,`int64`

,`complex64`

, or`complex128`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

.

`tf.Variable.__radd__(a, *args)`

{:#Variable.**radd**}

Returns x + y element-wise.

*NOTE*: `Add`

supports broadcasting. `AddN`

does not. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

. Must be one of the following types:`half`

,`float32`

,`float64`

,`uint8`

,`int8`

,`int16`

,`int32`

,`int64`

,`complex64`

,`complex128`

,`string`

.: A`y`

`Tensor`

. Must have the same type as`x`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

. Has the same type as `x`

.

`tf.Variable.__rand__(a, *args)`

{:#Variable.**rand**}

Returns the truth value of x AND y element-wise.

*NOTE*: `LogicalAnd`

supports broadcasting. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

of type`bool`

.: A`y`

`Tensor`

of type`bool`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

of type `bool`

.

`tf.Variable.__rdiv__(a, *args)`

{:#Variable.**rdiv**}

Returns x / y element-wise.

*NOTE*: `Div`

supports broadcasting. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

. Must be one of the following types:`half`

,`float32`

,`float64`

,`uint8`

,`int8`

,`uint16`

,`int16`

,`int32`

,`int64`

,`complex64`

,`complex128`

.: A`y`

`Tensor`

. Must have the same type as`x`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

. Has the same type as `x`

.

`tf.Variable.__rfloordiv__(a, *args)`

{:#Variable.**rfloordiv**}

Divides `x / y`

elementwise, rounding down for floating point.

The same as `tf.div(x,y)`

for integers, but uses `tf.floor(tf.div(x,y))`

for
floating point arguments so that the result is always an integer (though
possibly an integer represented as floating point). This op is generated by
`x // y`

floor division in Python 3 and in Python 2.7 with
`from __future__ import division`

.

Note that for efficiency, `floordiv`

uses C semantics for negative numbers
(unlike Python and Numpy).

`x`

and `y`

must have the same type, and the result will have the same type
as well.

##### Args:

:`x`

`Tensor`

numerator of real numeric type.:`y`

`Tensor`

denominator of real numeric type.: A name for the operation (optional).`name`

##### Returns:

`x / y`

rounded down (except possibly towards zero for negative integers).

##### Raises:

: If the inputs are complex.`TypeError`

`tf.Variable.__rmod__(a, *args)`

{:#Variable.**rmod**}

Returns element-wise remainder of division.

*NOTE*: `Mod`

supports broadcasting. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

. Must be one of the following types:`int32`

,`int64`

,`float32`

,`float64`

.: A`y`

`Tensor`

. Must have the same type as`x`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

. Has the same type as `x`

.

`tf.Variable.__rmul__(a, *args)`

{:#Variable.**rmul**}

Dispatches cwise mul for "Dense*Dense" and "Dense*Sparse".

`tf.Variable.__ror__(a, *args)`

{:#Variable.**ror**}

Returns the truth value of x OR y element-wise.

*NOTE*: `LogicalOr`

supports broadcasting. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

of type`bool`

.: A`y`

`Tensor`

of type`bool`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

of type `bool`

.

`tf.Variable.__rpow__(a, *args)`

{:#Variable.**rpow**}

Computes the power of one value to another.

Given a tensor `x`

and a tensor `y`

, this operation computes \(x^y\) for
corresponding elements in `x`

and `y`

. For example:

```
# tensor 'x' is [[2, 2], [3, 3]]
# tensor 'y' is [[8, 16], [2, 3]]
tf.pow(x, y) ==> [[256, 65536], [9, 27]]
```

##### Args:

: A`x`

`Tensor`

of type`float32`

,`float64`

,`int32`

,`int64`

,`complex64`

, or`complex128`

.: A`y`

`Tensor`

of type`float32`

,`float64`

,`int32`

,`int64`

,`complex64`

, or`complex128`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

.

`tf.Variable.__rsub__(a, *args)`

{:#Variable.**rsub**}

Returns x - y element-wise.

*NOTE*: `Sub`

supports broadcasting. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

. Must be one of the following types:`half`

,`float32`

,`float64`

,`int32`

,`int64`

,`complex64`

,`complex128`

.: A`y`

`Tensor`

. Must have the same type as`x`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

. Has the same type as `x`

.

`tf.Variable.__rtruediv__(a, *args)`

{:#Variable.**rtruediv**}

Divides x / y elementwise, always producing floating point results.

The same as `tf.div`

for floating point arguments, but casts integer arguments
to floating point before dividing so that the result is always floating point.
This op is generated by normal `x / y`

division in Python 3 and in Python 2.7
with `from __future__ import division`

. If you want integer division that
rounds down, use `x // y`

or `tf.floordiv`

.

`x`

and `y`

must have the same numeric type. If the inputs are floating
point, the output will have the same type. If the inputs are integral, the
inputs are cast to `float32`

for `int8`

and `int16`

and `float64`

for `int32`

and `int64`

(matching the behavior of Numpy).

##### Args:

:`x`

`Tensor`

numerator of numeric type.:`y`

`Tensor`

denominator of numeric type.: A name for the operation (optional).`name`

##### Returns:

`x / y`

evaluated in floating point.

##### Raises:

: If`TypeError`

`x`

and`y`

have different dtypes.

`tf.Variable.__rxor__(a, *args)`

{:#Variable.**rxor**}

x ^ y = (x | y) & ~(x & y).

`tf.Variable.__sub__(a, *args)`

{:#Variable.**sub**}

Returns x - y element-wise.

*NOTE*: `Sub`

supports broadcasting. More about broadcasting
here

##### Args:

: A`x`

`Tensor`

. Must be one of the following types:`half`

,`float32`

,`float64`

,`int32`

,`int64`

,`complex64`

,`complex128`

.: A`y`

`Tensor`

. Must have the same type as`x`

.: A name for the operation (optional).`name`

##### Returns:

A `Tensor`

. Has the same type as `x`

.

`tf.Variable.__truediv__(a, *args)`

{:#Variable.**truediv**}

Divides x / y elementwise, always producing floating point results.

The same as `tf.div`

for floating point arguments, but casts integer arguments
to floating point before dividing so that the result is always floating point.
This op is generated by normal `x / y`

division in Python 3 and in Python 2.7
with `from __future__ import division`

. If you want integer division that
rounds down, use `x // y`

or `tf.floordiv`

.

`x`

and `y`

must have the same numeric type. If the inputs are floating
point, the output will have the same type. If the inputs are integral, the
inputs are cast to `float32`

for `int8`

and `int16`

and `float64`

for `int32`

and `int64`

(matching the behavior of Numpy).

##### Args:

:`x`

`Tensor`

numerator of numeric type.:`y`

`Tensor`

denominator of numeric type.: A name for the operation (optional).`name`

##### Returns:

`x / y`

evaluated in floating point.

##### Raises:

: If`TypeError`

`x`

and`y`

have different dtypes.

`tf.Variable.__xor__(a, *args)`

{:#Variable.**xor**}

x ^ y = (x | y) & ~(x & y).

`tf.Variable.from_proto(variable_def)`

Returns a `Variable`

object created from `variable_def`

.

`tf.Variable.initial_value`

Returns the Tensor used as the initial value for the variable.

Note that this is different from `initialized_value()`

which runs
the op that initializes the variable before returning its value.
This method returns the tensor that is used by the op that initializes
the variable.

##### Returns:

A `Tensor`

.

`tf.Variable.ref()`

Returns a reference to this variable.

You usually do not need to call this method as all ops that need a reference to the variable call it automatically.

Returns is a `Tensor`

which holds a reference to the variable. You can
assign a new value to the variable by passing the tensor to an assign op.
See `value()`

if you want to get the value of the
variable.

##### Returns:

A `Tensor`

that is a reference to the variable.

`tf.Variable.to_proto()`

Converts a `Variable`

to a `VariableDef`

protocol buffer.

##### Returns:

A `VariableDef`

protocol buffer.

`tf.Variable.value()`

Returns the last snapshot of this variable.

You usually do not need to call this method as all ops that need the value
of the variable call it automatically through a `convert_to_tensor()`

call.

Returns a `Tensor`

which holds the value of the variable. You can not
assign a new value to this tensor as it is not a reference to the variable.
See `ref()`

if you want to get a reference to the
variable.

To avoid copies, if the consumer of the returned value is on the same device as the variable, this actually returns the live value of the variable, not a copy. Updates to the variable are seen by the consumer. If the consumer is on a different device it will get a copy of the variable.

##### Returns:

A `Tensor`

containing the value of the variable.