====== MXR Command ======
MXR,<p>,<row>,<t1>,<t2>,…<t12>

sets the terms belonging the real part of the stiffness matrix of matrix property <p>, row <row>  to <t1> - <t12>. If the matrix property <p> does not exist, it will be created by this command. Since the matrix is upper-diagonal, enter only the required number of terms from the diagonal to the right, i.e., for the first row use <t1> - <t12>, for the second row <t1> - <t11>, and for the last row ( <row> = 12), only <t1>.