% for problem 14.1.2

Z = load('th.txt');    % loading the values of temperture and humidity from the table

[X,Y] = meshgrid(80:5:100, 20:10:70);   % entering X and Y that is T and h ranges 

surf(X,Y,Z'); 
    xlabel('Temperature');  ylabel('Humidity');  title('Apparent Temperature')

    
%% here's a sketch of some function we already know 
 xyrange = -2:0.1:2;

  [X,Y] = meshgrid(xyrange, xyrange);
  
  Z = X.^2 - Y.^2; 
  
  surf(X,Y,Z);
  
  % *contours* are traces when z = k:
  
     ezmeshc('x^2 - y^2',[-2,2,-2,2])
     
     
  %% this is the surface from exam 1. Half of it, anyway.... 
  
    ezmeshc('sqrt(4*y^2-1)',[-2,2,-2,2])
      hold on 
    ezmeshc('-sqrt(4*y^2-1)',[-2,2,-2,2])   % the other half...
      hold off
  
  
    % #39 
    
    ezmeshc('y - log(x)',[-3,3,-3,3])