ComposeMVector[m,c] composes an m-element as a linear combination of basis elements in the currently declared basis. If the Origin is one of the basis elements it is ignored. If the Origin is not present, ComposeMVector will give the same result as ComposeMElement. The coefficients of the components are symbolic scalars of the form Subscript[c, i].ComposeMVector[m,c,s] starts the subscript indices at s.