# Initial Conditions Parameters

This sets of parameters, contained in the namelist block `&INIT_PARAMS`. This is used to set up the initial conditions.
 
| Variable name, syntax, default value | Fortran type | Description |
|:---------------------------- |:------------- |:------------------------- |
| `nregion=1`  | `integer` | Number of independent regions in the computational box used to set up initial flow variables. |
| `region_type=square`  | `10*char` | Geometry defining each region. `square` defines a generalized ellipsoidal shape, while `point` defines a delta function in the flow. |
| `x_center=0.0`  | `real arrays` | X coordinate of the center of each region. |
| `y_center=0.0`  | `real arrays` | Y coordinate of the center of each region. |
| `z_center=0.0`  | `real arrays` | Z coordinate of the center of each region. |
| `length_x=0.0`  | `real arrays` | Size in X direction of each region. |
| `length_y=0.0`  | `real arrays` | Size in Y direction of each region. |
| `length_z=0.0`  | `real arrays` | Size in Z direction of each region. |
| `exp_region=2.0`  | `real arrays` | Exponent defining the norm used to compute distances for the generalized ellipsoid. `exp_region=2` corresponds to a spheroid, `exp_region=1` to a diamond shape, `exp_region>=10` to a perfect square. |
| `d_region=0.0`  | `real arrays` | Density. For `point` regions this is used to define mass. |
| `u_region=0.0`  | `real arrays` | X velocity. For `point` regions this is used to define velocity. |
| `v_region=0.0`  | `real arrays` | Y velocity. For `point` regions this is used to define velocity. |
| `w_region=0.0`  | `real arrays` | Z velocity. For `point` regions this is used to define velocity. |
| `p_region=0.0`  | `real arrays` | Pressure. For `point` regions this is used to define specific pressure. |
| `filetype=ascii`  | `20*char` | Type of initial conditions file for particles. Possible choices are `ascii` or `grafic`. |
| `aexp_ini=10.0`  | `real` | This parameter sets the starting expansion factor for cosmology runs only. Default value is read in the IC file. |
| `multiple=.false.` | `logical` | If `.true.`, each processors reads its own IC file. For parallel runs only. |
| `initfile= ` | `80*char` | Directory where IC files are stored.


**WORK IN PROGRESS**