Could you be more clear about your map structure? In MDS coordinate values are not really required. It is about the quadrants and the spatial locations of the objects along with vectors (for attribute based MDS)

These values are required to identify whether we are getting positive or negative values for each dimension for all the variable we have considered.The quadrants and spatial location are the end result.My questions was on what basis we are getting these co-ordinate values. 

The answer to your question is that the system or software does the placing based on iterative program.  You must be aware that the option of simple euclidian/ weighted euclidian n others are present. The computrer uses your chosen method and calclutes the distance. The negative coordinates mean rating below the mean rating or ranking.

Thanks for your comment.I know whatever you have written but I want the mathematical logic behind it not the iteration of software  as to understand it clearly you must have to know how you have derived and from where. 

Thanks a lot.