1. A computer implemented method for solving a numerical problem with user input comprising the steps of: a) receiving restrictions from computer memory including constraint expressions with at least one inequality; and b) iteratively solving said numerical problem with a computer processor including the steps of: i) determining a solution of said numerical problem with variable values that satisfy restrictions; ii) displaying graphical objects representing said variable values on a computer display; said step of displaying including displaying said variable values as bar charts; and iii) manipulating said displayed graphical objects based on user input provided through a computer input device to obtain additional restrictions; said step of manipulating including obtaining constraints on said variable values, and said step of manipulating including obtaining additional restrictions as said displayed bar charts are manipulated.