function main
 format long e
 x = 1.1
 f = @sin
 fp = @cos
 fpx = fp(x)
 
 hmin = 1.0e-14;
 hmax = 1.0e-2;
 
 loghmin = log10(hmin);
 loghmax = log10(hmax);
 
 npts = 500;
 logh = linspace(loghmin,loghmax,npts);
 h = 10.^logh;
 fdh = getfd(f,x,h);
 err = fdh - fpx;
 logabserr = log10(abs(err));
 plot(logh,logabserr)
 xlabel('log10 h');
 ylabel('log10 error');
 title('Error in forward difference approx to derivative');

end

function fds=getfd(f,x,h)
 fds = (f(x+h)-f(x))./h
end