The production matrix can be solved by the formula: X = (I ¡A)¡1D The introduction chronicles how the input–output framework, conceived originally by Wassily Leontief in the s, has matured over the last seven ades to become a key component of many types of economic analysis and one of the most widely applied methods in economics The calculation AX = X ¡ D is the internal use of the model. To effectively use these models, analysts must collect detailed information about the project or program und