---
title: EvaluationNode (latest version)
description: API reference for samplomatic.samplex.nodes.EvaluationNode in the latest version of samplomatic
source: https://eu-de.quantum.cloud.ibm.com/docs/en/api/samplomatic/auto/samplex-nodes-evaluation-node
---

# EvaluationNode

*class* `samplomatic.samplex.nodes.EvaluationNode`

[GitHub](https://github.com/Qiskit/samplomatic/tree/main/samplomatic/samplex/nodes/evaluation_node.py#L24-L40)

Bases: [`ABC`](https://docs.python.org/3/library/abc.html#abc.ABC), [`Node`](/docs/api/samplomatic/auto/samplex-nodes-node "samplomatic.samplex.nodes.node.Node")

A node that evaluates on an existing register state.

**Methods Summary**

|                                                                                                                                                    |                     |
| -------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------- |
| [`evaluate`](#samplomatic.samplex.nodes.EvaluationNode.evaluate "samplomatic.samplex.nodes.EvaluationNode.evaluate")(registers, parameter\_values) | Evaluate this node. |

**Methods Documentation**

### evaluate

*abstractmethod* `evaluate(registers: dict[str, VirtualRegister], parameter_values: ndarray)`

[GitHub](https://github.com/Qiskit/samplomatic/tree/main/samplomatic/samplex/nodes/evaluation_node.py#L27-L40)

Evaluate this node.

**Parameters**

- **registers** – At least those registers needed by this node to read from or write to.
- **parameter\_values** – Parameter values to use during evaluation.

**Raises**

[**SamplexRuntimeError**](/docs/api/samplomatic/auto/exceptions-samplex-runtime-error "samplomatic.exceptions.SamplexRuntimeError") – If the number of parameter values received does not equal the number required by this node.