Figure 1. Using modules from the STABLE project to perform a non-linear optimisation with two Excel-based modules. The instance of Excel on the left (started by the SQPCalculate module in the map) is displaying the data points and the cubic that is being fitted to them. The module communicates dynamically with the Minimise by SQP module in the map; this uses a routine from the NAG Fortran Library to perform the optimisation by minimising the sum of the squares. The output from the SQPCalculate module is passed to the ExcelMod, which uses another instance of Excel to display the sum of the squares as a function of iteration number.