code: public static boolean cs_entry(DZcs T, int i, int j, double [] x)
  	{
  		return cs_entry(T, i, j, x [0], x [1]);
  	}
docs: Adds an entry to a triplet matrix. Memory-space and dimension of T are
  increased if necessary.
  
  @param T
  triplet matrix; new entry added on output
  @param i
  row index of new entry
  @param j
  column index of new entry
  @param x
  numerical value of new entry
  @return true if successful, false otherwise