# getValue

Obtain estimated value from a critic given environment observations and actions

## Syntax

## Description

### Value Function Critic

evaluates the value function critic `value`

= getValue(`valueFcnAppx`

,`obs`

)`valueFcnAppx`

and returns the
value corresponding to the observation `obs`

. In this case,
`valueFcnAppx`

is an `rlValueFunction`

approximator object.

### Q-Value Function Critics

evaluates the discrete-action-space Q-value function critic
`value`

= getValue(`vqValueFcnAppx`

,`obs`

)`vqValueFcnAppx`

and returns the vector `value`

,
in which each element represents the estimated value given the state corresponding to the
observation `obs`

and the action corresponding to the element number of
`value`

. In this case, `vqValueFcnAppx`

is an
`rlVectorQValueFunction`

approximator object.

evaluates the Q-value function critic `value`

= getValue(`qValueFcnAppx`

,`obs`

,`act`

)`qValueFcnAppx`

and returns the
scalar `value`

, representing the value given the observation
`obs`

and action `act`

. In this case,
`qValueFcnAppx`

is an `rlQValueFunction`

approximator object.

## Examples

## Input Arguments

## Output Arguments

## Tips

The more general function `evaluate`

behaves, for
critic objects, similarly to `getValue`

except that
`evaluate`

returns results inside a single-cell array.

para

## Version History

**Introduced in R2020a**