User-guide.md

 Once installed, BLASTER is initialized using the following lines:
 ```python
+from blaster.blast.api.blaster_api import init_blaster
+_blast = init_blaster(cfg, icfg, iSolverName, task)
 ```
-where the parameters are...
+where:
+- `_blast` is a Python dictionary containing the objects required to run BLASTER
+- `cfg` is a Python dictionary that configures the viscous solver
+- `icfg` is a Python dictionary that configures the inviscid solver (e.g. see [DART](https://gitlab.uliege.be/am-dept/dartflo/-/wikis/use_api_core))
+- `iSolverName` is the name of the inviscid solver (available options: `'DART'`)
+- `task` is the type of calculation to be made (available options: `'analysis'`, `'optimization'`)
 
-This will return...
+The configuration dictionary `cfg`consists of the parameters defined here under:
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+```python
+cfg = {
+'Re': float # Flow Reynolds number.
+'Minf': float # Freestream Mach number (only used for time step computation).
+'CFL0': float # Initial CFL number.
+'Verb': int # Verbosity level of the viscous solver.
+'xtrF': [float, float] # Forced transition location [upper, lower].
+'couplIter': int # Maximum number of coupling iterations.
+'couplTol': float # Tolerance to end computation (drag count between 2 iterations).
+'iterPrint': int # Number of iterations between which the coupler outputs its state.
+'resetInv': bool # Resets the inviscid solver at each iteration (True), reuses previous state as initial condition (False).
+}
+```
+
+The return dictionary `_blast` contains:
+- `coupler`: the coupler driving the viscous inviscid process
+- `isol`: the interface of the inviscid solver (see `blast/interfaces/DSolversInterface.py`)
+- `vsol`: the viscous solver
+- `adj`: the coupled viscous inviscid adjoint solver
+
+
+A viscous inviscid solution is then obtained by:
+```python
+coupler.run()
+```
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