1. A computer readable storage memory having stored thereon computer executable instructions for calculating a value using a model based spreadsheet scripting language, the computer executable instructions comprising: executing a program that defines a value for a second variable based on a value for a first variable, the program written in the model based spreadsheet scripting language whereby the value for the second variable changes repeatedly when the value for the first variable changes repeatedly, the program comprising a textual representation of at least a portion of a spreadsheet and a plurality of formulas contained in the spreadsheet, the spreadsheet comprising a first cell having a first value that is model-based and that is recalculated when the value of the first variable changes, the model based spreadsheet language incorporating procedural elements for calculation of spreadsheet values and thereby enabling a second cell having a second value that is not model-based and that is recalculated in response to selection of a reset function; receiving the value for the first variable; calculating the value for the second variable based on the value for the first variable in the program; and, generating an output comprising the calculated value for the second variable.