Obviously, when I have to plot x, this three parameter; what I will do, I have this versus this for a number of values for one of them for a given value of this. So, basically repeat it, remember there was a statement I heard earlier. That if y was a function of x 1, you need one graph; if it is x 1 and x 2, you have number of graph; if it is x 1, x 2 and x 3, then you have to repeat this number of graph number of times. This very obvious, is not it? See if y is a function of x x 1 just one parameter, one line will suffice to define that; if it is a function of x 1 and x 2, you will have y versus x 1 for different value of x 2; that means, you will end up having number of graph. If it is y is a function of x 1, x 2 and x 3, then these numbers of graph are to be repeated for different value of x 3. So, you end up repeating. There is a statement that if it is 3 you require number of pages and it is 4 you will require a book and 5 you require a library to represent them because it goes one time more.