Source Mixture Model

        This application models a set of source mixtures against a set of samples for which each component has been measured.
        
        Source mixture compositions and the contribution of each source mixture to each sample are the results of the model.

        Source Mixture Model is a mixing model.  It uses regression to fit experimental data to a set of source mixtures.  
        Examples include environmental mixtures of lipids or clay minerals.

        To use the simplemax nonlinear regression tool enter data and the number of source mixtures to be modelled in 
        the appropriate boxes.  Optionally, initial values of the source component fractions and source mixture fractions 
        may be adjusted.  Optionally, the regression parameters may be adjusted.  Low and high bounds are set automatically.  

        Data should be arranged one datapoint on each line, with the variables x1 ... xn in order.

        The Source Mixture Model function is
        
             residual = sum n( sum c( sum m(componentc * mixture m - fraction(data nc) ) ) ),   
        
        which is minimized.