function z = c_4_p_18_fn_i(x,y)
[n1,n2] = size(x); [m1,m2] = size(y);
if (n1==1) && (m1==1) 
  [xx,yy] = meshgrid(x,y);
  T = sqrt( xx / 3 ) - 1;
  z = exp( ( T .* yy + 1 ).^3 ) .* T;
else
  disp('x and y must be scalars or row vectors'); return; 
end