| 75 | |

| 76 | Softening is a numerical trick commonly used in simulations to prevent divergences when a value comes close to another and the force of gravity goes to infinity.[[BR]] |

| 77 | In our case, as the radius of the disk gets smaller, the force of gravity is approximated to a well defined value.[[BR]] |

| 78 | |

| 79 | Problem.data provides a field in which the user can set the preferred softening parameter: |

| 80 | |

| 81 | {{{ |

| 82 | soft_radius=.333d0 !diks radii |

| 83 | soft_function=2 !NOSOFT=0, SPLINESOFT=1, PLUMMERSOFT=2 |

| 84 | }}} |

| 85 | |

| 86 | The plot below shows 3 different scenarios: |

| 87 | |

| 88 | [[Image(fgrav.png, 800px)]] |

| 89 | |

| 90 | - No Softening: the force of gravity goes to infinity as the radius decreases |

| 91 | - Softening enabled: the force of gravity has a well defined value at r=0 |

| 92 | - Increased softening radius: the force of gravity has a lower value at r=0 compared to the previous case |

| 93 | |

| 94 | Astrobear provides different softening techniques such as SplineSoft and PlummerSoft, the user can set the softening function depending on the simulation needs. |

| 95 | |

| 96 | '''Warning: ''' It is good practice to keep the soft_radius between .1 and .3. Failure to do so may result in undesired outcomes. |

| 97 | |

| 98 | |