Other properties

  There are a number of other properties attached to an indexed object either by mkobj() or by other functions in the system. A partial list of these property keys and the type of their values follows. Those flagged with an asterisk are shown by the iprop() function.

altmetric:id-list

--- A list of metrics to be used instead of those in currentmetric, settable by the user with the altmetric() function.

conjugate:list

--- The name (in a list) of the conjugate object associated with a spinor. The conjugate object has the primary object's name and a flag under this key.

coords:id-list

--- A copy of the coords!* environment variable at the time the object was created (see §2.4.1).

cov:list

--- The first element of the list is the order of the derivative, the second element is the name of the anti-derivative of this object (nil if this is the parent), the third element is the name of the derivative of this object (nil if it does not exist).

description:string

--- a description string that may be set or examined via the function describe().

det:aexp

--- The value of the determinant of the object (which must be rank-2), as computed by the det() or determ() functions.

div:id

--- The name of the divergence object, created from this object by the function div().

indexed:id

--- the property by which the system identifies indexed object names. The value under this property will be one of: array -- if all indices in indextype are array indices tensor -- if all indices are tensor indices frame -- if all indices are frame indices spinor -- if all indices are either primed or unprimed spinor indices dyad -- if all indices are either primed or unprimed dyad indices scalar -- if indextype is the empty list, indicating a scalar object mixed -- if indextype contains more than one kind of index. other values may appear as defined by the user (see defindextype()).

indextype:int-list

--- The user-input indextype list.

implicit:id

--- The implicit parameter, usually the same as the object's name.

indices:list

--- An internal representation derived from the lisp:defindextype!* lists.

multiplier:aexp

--- A common factor, most often non-unity for metric (or array) inverses.

parent:id

--- For a shifted object, this is the object from which it was derived.

printname:id

--- The name used to display the object in indexed form. This may be different from the actual object name if the object is generic (see §4.3) or has shifted indices (see §3.1).

protection:int

--- The internal format of the protection flags, the numbers 2, 3, or 6, which correspond to write-prtotection, kill-protection, or both; or nil for no protection.

odf:list

--- The list is in the same format as for the cov property; it holds the names of ordinary derivatives.

restricted:list

--- A restricted indices property, set by the user with the restrict() function.

shift:list

--- A list of names of shifted objects derived from this one. Each of these objects will not have this property, but will have the parent property instead. See 3.1 for more details.

symmetry:list-list

--- The internal format of the user input symmetry list.

itype:any

--- The user input itype parameter.

tvalue:alist

--- the association list of indices and component values.