pvPacki
==============================================

Purpose
----------------

Packs general matrix or array into a :class:`PV` instance with name and index.

Format
----------------
.. function:: p1 = pvPacki(p1, x, nm, i)

    :param p1: an instance of structure of type :class:`PV`
    :type p1: struct

    :param x: data
    :type x: MxN matrix or N-dimensional array

    :param nm: name of matrix or array, or null string.
    :type nm: string

    :param i: index of matrix or array in lookup table.
    :type i: scalar

    :return p1: instance of :class:`PV` struct.

    :rtype p1: struct

Examples
----------------

::

    y = rndn(100, 1);
    x = rndn(100, 5);

    // Declare 'p1' as an instance of a 'PV' structure
    struct PV p1;

    // Initialize 'p1' with default values
    p1 = pvCreate;

    // Pack the variables in with a variable name and an index
    p1 = pvPacki(p1, y, "Y", 1);
    p1 = pvPacki(p1, x, "X", 2);

These matrices can be extracted using the :func:`pvUnpack` command, indicating the variable to unpack either by index or by variable name:

::

    // Unpack variables by index
    y = pvUnpack(p1, 1);
    x = pvUnpack(p1, 2);

    // Unpack variables by variable name
    y = pvUnpack(p1, "Y");
    x = pvUnpack(p1, "X");

.. seealso:: Functions :func:`pvPack`, :func:`pvUnpack`