(calibration_circe_tcirce)=
# Constructing the `TCirce` object

To create an instance of the `TCirce` class, the constructor is available with the following prototype:

````{only} cpp
```cpp
TCirce(URANIE::DataServer::TDataServer *tds, const char *systar, const char *syhat, const char *ssensi, const char *sexpuncert = "", Option_t * option = "");
```
````

````{only} py
```python
TCirce(tds, systar, syhat, ssensi, sexpuncert = "", option = "")
```
````

This method takes up to six arguments, two of which are optional:

1. **tds**: a {{tds}} object containing:
   - one attribute for the experimental data, 
   - one attribute for the code output, 
   - and the attributes corresponding to the derivatives of the code output with respect to each parameter (one attribute per parameter).

2. **systar**: name of the experimental attribute;

3. **syhat**: name of the code output attribute;

4. **ssensi**: list of attribute names corresponding to the derivatives of the code output with respect to each parameter, separated by commas ",";
   
5. **sexpuncert** (optional): name of the experimental uncertainty attribute;
   
6. **option** (optional): currently, no options are implemented for this class.