I.6.4 “Operator” methods

Five “operator” methods (functions) are defined in the “Post” module: “opAdd”, “opSub”, “opMul”, “opDiv” and “opPow”. The four first methods correspond to the four “+”, “-”, “*” and “/” operators defined in “Result”, “Group” and “ResKeyList” classes:

• If first argument is a “Group” object, the second argument must also be a “Group” object.
• If first argument is a “ResKeyList” object, the second argument must also be a “ResKeyList” object.
• If either first or second argument is a “Result” object, then the possible arguments are those of the corresponding operators in “Result” class (section I.4.7).

  The first argument can be a “Result” object, a real value, a complex value, an Array of three real values or three complex values, or a $3\times 3$ matrix of real elements.

  The second argument can be a “Result” object, a real value, a complex value, an Array of three real values, or a $3\times 3$ matrix of real elements.

The “opPow” method is an alias to the “pow” method and at least one of its arguments must be a “Result” object.