fmri_vol2vect
=============

.. currentmodule:: fmri_toolbox

Description
-----------
FMRI_VOL2VECT  Vectorizes a 91x109x91 brain volume to a 228453-element vector.
Extracts the brain voxels from a 3D or 4D volume array, returning a compact
matrix in which each row is a brain voxel. Non-brain voxels (outside the
standard MNI152 2mm brain mask) are discarded. This is the canonical data
format used throughout the toolbox.

Usage
-----
.. code-block:: matlab

    v = fmri_vol2vect(vol)
    v = fmri_vol2vect(vol, mask)

Inputs
------
- **VOL**: Volume array of size (91 x 109 x 91) or (91 x 109 x 91 x T). Must match the standard MNI152 2mm grid exactly.
- **MASK**: Binary brain mask (91 x 109 x 91). Optional. If omitted, the standard toolbox brain mask (standard_brain_NZ.mat) is used.

Outputs
-------
- **V**: Vectorized data: (228453 x 1) for a single volume, or (228453 x T) for a time series.

Examples
--------
.. code-block:: matlab

    v   = fmri_vol2vect(volume);             % standard mask
    v   = fmri_vol2vect(timeseries_4d);      % 228453 x T
    v   = fmri_vol2vect(volume, my_mask);    % custom mask

Notes
-----
- The standard brain mask defines 228453 in-brain voxels from the
- 91x109x91 MNI152 2mm template (total voxels: 897,609). The number 228453
- is therefore a constant throughout the toolbox.

See Also
--------
- fmri_vect2vol
- fmri_vol2vect