*Last updated: 2023-03-16.*
# tf_quant_finance.math.make_val_and_grad_fn
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Function decorator to compute both function value and gradient.
```python
tf_quant_finance.math.make_val_and_grad_fn(
value_fn
)
```
#### For example:
```
@tff.math.make_val_and_grad_fn
def quadratic(x):
return tf.reduce_sum(scales * (x - minimum) ** 2, axis=-1)
```
Turns `quadratic` into a function that accepts a point as a `Tensor` as input
and returns a tuple of two `Tensor`s with the value and the gradient of the
defined quadratic function evaluated at the input point.
This is useful for constructing functions to optimize with tff.math.optimizer
methods.
#### Args:
* `value_fn`: A python function to decorate.
#### Returns:
The decorated function.