29 Mar
                
                    2016
                
            
            
                29 Mar
                
                '16
                
            
            
            
        
    
                6:48 p.m.
            
        On 29 Mar 2016, at 17:49, Lawrence Mitchell <lawrence.mitchell@imperial.ac.uk> wrote:
Without boundary conditions this problem is ill posed. The lay factorisation is failing, presumably due to zero pivot.
Sorry, I misread, utilde isn't a trial function. Lawrence