function f=fenceDem(infile, outfile)
%open infile for read
in = fopen(infile,'r');
%open outfile for write
out = fopen(outfile, 'w');
%get input from infile
%the values are in vector y and the total number of values is in "count"
[y, count] = fscanf(in, '%d', inf);
%calculate all pairs (using for loop)
for i=1:1:count/2
W = y(2*i-1);
A = y(2*i);
% we know
% WL + 0.5*D^2 = A, and
% W=sqrt(2)*D
% so we have WL + 0.25*W^2 = A
% solve this equation and we get
L = (A-0.25*W^2)/W;
%output the L value to outfile
fprintf(out, '%f\n', L);
end
%close all the files we opened
fclose(in);
fclose(out);