1. An electronic mathematical model builder comprising: a memory for storage of data, a processor for defining panels of cells stored in the memory, for entering data into the cells and for processing data stored in the cells, a user interface component with a display for displaying panels of cells in a work area and for specifying input data to be entered into the cells of at least one input panel, and a function builder component configured for establishing a function comprising mathematical relations between the at least one input panel and an output panel with a plurality of cells, the established function being stored independently from the plurality of cells and not inherently connected with the plurality of cells via a special token used to invoke the established function, the function builder comprising fields for user specification of a desired function by mathematical operators, and input variables of the function, wherein the processor determines respective output function values for the input data of the at least one input panel according to the established function, the established function being separate from the output function values.