% dmSecond7Pt.m
%          

 function dm = dmSecond7Pt(x) 

     N = length(x);
     h = abs(x(2)-x(1));
      
      up3 = diag(ones(1,N-3)/90,3);
      up2 = diag(-0.15*ones(1,N-2),2);
      up1 = diag(1.5*ones(1,N-1),1);
     low1 = diag(1.5*ones(1,N-1),-1);
     low2 = diag(-0.15*ones(1,N-2),-2);
     low3 = diag(ones(1,N-3)/90,-3);
        d = diag(-49*ones(1,N)/18);
        
      dm = d + low1 + up1 + low2 + up2 + low3 + up3;
     
    
     dm(2,1) = 137/180;  dm(2,2) = -49/60;  dm(2,3) = -17/12;  dm(2,4) = 47/18; dm(2,5) = -19/12;  dm(2,6) = 31/60;  dm(2,7) = -13/180;
     dm(3,1) = -13/180;  dm(3,2) = 19/15;  dm(3,3) = -7/3;  dm(3,4) = 10/9; dm(3,5) = 1/12;  dm(3,6) = -1/15; dm(3,7) = 1/90;
     
     dm(N-2,N-6) = 1/90;     dm(N-2,N-5) = -1/15;  dm(N-2,N-4) = 1/12;    dm(N-2,N-3) = 10/9;  dm(N-2,N-2) = -7/3;    dm(N-2,N-1) = 19/15;   dm(N-2,N) = -13/180;
     dm(N-1,N-6) = -13/180;  dm(N-1,N-5) = 31/60;  dm(N-1,N-4) = -19/12;  dm(N-1,N-3) = 47/18; dm(N-1,N-2) = -17/12;  dm(N-1,N-1) = -49/60;  dm(N-1,N) = 137/180;
     

     
     dm = dm./(h^2);