The 'Pellian' Equation is of the form:-
X^2 - D.Y^2 = 1 , to be 'solved' for a given fixed whole positive D (non-square) and some whole X and Y. !Pellian produces a series of solutions for X and Y, until the numbers get too large for computer representation. Sometimes all solutions are too large. Warns if this happens. 'Help' window, and 'Save to File' options are available.