*Last updated: 2023-03-16.*
# tf_quant_finance.utils.broadcast_common_batch_shape
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Broadcasts argument batch shapes to the common shape.
```python
tf_quant_finance.utils.broadcast_common_batch_shape(
*, event_ranks=None, name=None, *args
)
```
Each input `Tensor` is assumed to be of shape `batch_shape_i + event_shape_i`.
The function finds a common `batch_shape` and broadcasts each `Tensor` to
`batch_shape + event_shape_i`. The common batch shape is the minimal shape
such that all `batch_shape_i` can broadcast to it.
#### Example 1. Batch shape is all dimensions but the last one
```python
import tensorflow as tf
import tf_quant_finance as tff
# Two Tensors of shapes [2, 3] and [2]. The batch shape of the 1st Tensor is
# [2] and for the second is []. The common batch shape is [2]
args = [tf.ones([2, 3], dtype=tf.float64), tf.constant([True, False])]
tff.utils.broadcast_common_batch_shape(*args)
# Expected: (array([[1., 1., 1.], [1., 1., 1.]]),
# array([[True, True], [False, False]])
```
#### Example 2. Specify ranks of event shapes
```python
import tensorflow as tf
import tf_quant_finance as tff
args = [tf.ones([2, 3], dtype=tf.float64), tf.constant([True, False])]
tff.utils.broadcast_common_batch_shape(*args,
event_ranks)
# Expected: (array([[1., 1., 1.], [1., 1., 1.]]),
# array([[True, True], [False, False]])
```
#### Args:
* `*args`: A sequence of `Tensor`s of compatible shapes and any `dtype`s.
* `event_ranks`: A sequence of integers of the same length as `args` specifying
ranks of `event_shape` for each input `Tensor`.
Default value: `None` which means that all dimensions but the last one
are treated as batch dimension.
* `name`: Python string. The name to give to the ops created by this function.
Default value: `None` which maps to the default name
`broadcast_tensor_shapes`.
#### Returns:
A tuple of broadcasted `Tensor`s. Each `Tensor` has the same `dtype` as the
corresponding input `Tensor`.
#### Raises:
* `ValueError`: (a) If `event_ranks` is supplied and is of different from `args` length.
(b) If inputs are of incompatible shapes.