(STRESS-target)=
# STRESS
Exchange virial stress tensor.



## <STRESS

Receive virial stress tensor

**Datatype:** `MDI_DOUBLE`  
**Quantity**: `9`  

 The driver sends a virial stress tensor to the engine,  which replaces its internal stress tensor with the stress tensor sent by the driver.


### Examples


::::{tab-set}

:::{tab-item} Python
:sync: python

```python
import mdi

# connect to the engine
mdi_engine = mdi.MDI_Accept_Communicator()

# receive the virial stress tensor from the engine
mdi.MDI_Send_Command("<STRESS", mdi_engine)
stress = mdi.MDI_Recv(9, mdi.MDI_DOUBLE, mdi_engine)

```
:::

:::{tab-item} Python (NumPy)
:sync: python (numpy)

```python
import mdi
import numpy as np

# connect to the engine
mdi_engine = mdi.MDI_Accept_Communicator()

# create a buffer to hold the virial stress tensor
stress = np.zeros(9, dtype=float)

# receive the virial stress tensor from the engine
mdi.MDI_Send_Command("<STRESS", mdi_engine)
mdi.MDI_Recv(9, mdi.MDI_DOUBLE, mdi_engine, buf=stress)

```
:::

:::{tab-item} C++
:sync: cpp

```cpp
#include "mdi.h"

// connect to the engine
MDI_Comm mdi_engine = MDI_Accept_Communicator();

// create a buffer to hold the virial stress tensor
double stress[9];

// receive the virial stress tensor from the engine
MDI_Send_Command("<STRESS", mdi_engine);
MDI_Recv(stress, 9, MDI_DOUBLE, mdi_engine);

```
:::

::::

## >STRESS

Send virial stress tensor

**Datatype:** `MDI_DOUBLE`  
**Quantity**: `9`  

 Driver sends virial stress tensor to engine, replacing its internal tensor.