function V=mnhf_invu(U)
%MNHF_INVU inverts an upper triangular matrix
%
% U - the (square, upper triangular) matrix in question
%
% Usage  mnhf_invu(U);

[r,~] = size(U);  % Compute the size of U.
V = size(U);
for i=2:r   
 V(i,1:i-1) = 0.0;   % Elements below main diagonal.
end

for i=1:r
 V(i,i)=1.0/U(i,i); % Diagonal elements.
end
    
for j=2:r
 for i=j-1:-1:1
  % Elements above main diagonal.   
  V(i,j) = -1.0/U(i,i)*sum(U(i,i+1:j)*V(i+1:j,j));
 end
end