====== Fields at Nodes ======

===== Definition =====

Nodal fields (such as the displacement, the velocity, the temperature, etc.) are defined thanks to a combination of two "codes": a ''Nature'' and a ''Variant''.

  field = Field1D(Nature, Variant)

Here is a list of some ''Nature'' identifiers :

^  ''Nature''  ^  meaning  ^
| ''TX'' | X-coordinate |
| ''TY'' | Y-coordinate  |
| ''TZ'' | Z-coordinate  |
| ''TO'' | temperature  |
| ''TM'' | time|

and the most basic ''Variant'' ones

^  ''Variant''  ^  meaning  ^
| ''RE''  | relative |
| ''AB''  | absolute |
| ''GF1'' | force #1 - External Forces (reaction & contact) |
| ''GF2'' | force #2 - Internal Forces |
| ''GF3'' | force #3 - Inertial Forces |
| ''GV''  | first order derivative -- velocity|
| ''GA''  | second order derivative -- acceleration |

__Examples:__

The meaning of a given ''Field1D'' is deduced from the previous tables by combining the two components:

^  ''Field''          ^  meaning  ^
| ''Field1D(TX,RE)''  | "X-coordinate", "relative" = displacement along X     | 
| ''Field1D(TX,AB)''  | "X-coordinate", "absolute" = initial position along X |
| ''Field1D(TX,GF1)'' | "X-coordinate", "force #1" = external load along X    |
| ''Field1D(TY,GA)''  | "Y-coordinate", "acceleration" = acceleration along Y |


===== Common Nodal Fields used in Metafor =====

^   Field1D                                ^  Meaning in Metafor                    ^
| ''Field1D(TX,AB)'', ''Field1D(TY,AB)'', ''Field1D(TZ,AB)''    | initial positions ($x$, $y$ and $z$)   |
| ''Field1D(TX,RE)'', ''Field1D(TY,RE)'', ''Field1D(TZ,RE)''    | displacements ($x$, $y$ and $z$)       |
| ''Field1D(TO,AB)''                              | initial temperature                    |
| ''Field1D(TO,RE)''                              | temperature variation                  |
| ''Field1D(TX,GV)'', ''Field1D(TY,GV)'', ''Field1D(TZ,GV)''    | velocities ($v_x$, $v_z$ and $v_z$)    |
| ''Field1D(TX,GA)'', ''Field1D(TY,GA)'', ''Field1D(TZ,GA)''    | accelerations ($a_x$, $a_y$, $a_z$)    |
| ''Field1D(TM,RE)''                              | time                                   |
| ''Field1D(TX,GF1)'', ''Field1D(TY,GF1)'', ''Field1D(TZ,GF1)'' | mechanical external forces / contact forces |
| ''Field1D(TX,GF2)'', ''Field1D(TY,GF2)'', ''Field1D(TZ,GF2)'' | mechanical internal forces             |
| ''Field1D(TX,GF3)'', ''Field1D(TY,GF3)'', ''Field1D(TZ,GF3)'' | inertia forces                         |
| ''Field1D(TO,GF1)''                             | thermal external forces                |
| ''Field1D(TO,GF2)''                             | thermal external forces                |
| ...                                      | ...                                    |