MS_EXPAND - fill out elasticity matrix.

Expand a minimal set of elastic constants based on a specifed
            symmetry to a full Cij tensor.

[ Cf ] = MS_expand( C, mode )

Usage:
    Fill out elastic tensor C based on symmetry, defined by mode. This
    can take the following values:
       'auto'  - assume symmetry based on number of Cijs specified
       'iso'   - isotropic (nec=2) ; C33 and C66 must be specified.
       'hex'   - hexagonal (nec=5) ; C33, C44, C11, C66 and C13 must be
                 specified, x3 is symmetry axis
       'vti'   - synonym for hexagonal
       'cubic' - cubic (nec=3) ; C33, C66 and C12 must be specified
       'ortho' - orthorhombic (nec=9); All six diagonal (C11-C66), C12,
                 C13 and C23 must be specified

Cijs *not* specified in the appropriate symmetry should be zero in
the input matrix.

See also: MS_ELASTICDB MS_LOAD MS_LOAD_LIST