Floating type structures
========================

Array data are whatever data that can be contained in a multidimensional array
(also called multidimensional matrix).

An HDF5 dataset is simply a multidimensional array, the values's type of
elements in a dataset is the same for all elements. This type can be :

 * Integer
 * Real
 * Double
 * String
 * Complex

Besides, in physics matrices's dimensions are often linked to physical data.
For instance, the first dimension of a temporal pulse current is the time.
(The time being a one dimensional array (a vector) stored in a one dimensional
HDF5 dataset)

To assure this association  each matrix's dimension must be linked
to a dimension dataset : ::

    data.h5/
    |-- current # One dimensional real dataset parameterized by time
    `-- time    # One dimensional real dataset, current's abscissa 


A second example is a current density on a surface at a given frequency, the
current is a two dimensional matrix and the two dimensions are x and y
that are the cartesian coordinates of a grid : ::

    data.h5/
    |-- current # Two dimensional real datasets parameterized by x and y
    |-- x       # First dimension : one dimensional real dataset
    `-- y       # Second dimension : One dimensional real dataset


Numeric structures of this kind (one dimensional datasets,
multidimensional datasets, all manner to describing a list of numbers)
are used in many cases and **can be found out
everywhere** in an |namespec| file, they take the shape of HDF5 elements
having an attribute named **floatingType**.

The ``floatingType`` category
-----------------------------

In |namespec| ``floatingType`` are always children of another objects in
order to give it a meaning. However, it can happen a ``floatingType`` 
instance is orphan, for instance the result of a simulation can be only a time,
a real number. The ``floatingType`` category contains  orphan ``floatingType``.

Example (see :ref:`singleReal` for ``singleReal`` definition) :

::

    data.h5/
    |-- floatingType/
    |   `-- $flash_duration[@floatingType=singleReal
    |                       @label=flash duration
    |                       @physicalNature=time
    |                       @unit=second
    |                       @value=1e-9]
    `-- simulation/
        `-- $sim1[@module=my-module
            |     @version=1.2]
            |-- inputs
            `-- outputs

with ``data.h5:/simulation/$sim1/outputs`` :

+--------------------------------+
| /floatingType/$flash_duration  |
+--------------------------------+


.. include:: singletype.rst
.. include:: vector.rst
.. include:: rationalfractionfunctions.rst
.. include:: dataset.rst
.. include:: arrayset.rst
.. include:: expression.rst