Exercises for Pointer Variables
                      -------------------------------

1. Write a program, in which you:

   a) Define two pointers pv1 and pv2, where pv1 can point to a one 
      dimensional real array and pv2 can point to a two dimensional real array

   b) Define two target real arrays, tv1 and tv2, where tv1 is one dimensional 
      with bounds -3:5 and tv2 is two dimensional with bounds 1:5, 1:10 

   c) Set up the array pointer pv1 to point to tv1 such that pv1 has the 
      lower bound -3 (Write out the lower bound of pv1 for confirmation)

   d) Set up the array poinetr pv1 to point to tv1 such that pv1 has the 
      lower bound 1 (Write out the lower bound of pv1 for confirmation)

   e) Can you set pv1 to point to tv1 such that pv1 has the lower bound -2?
 
   f) Use pointers (pv1 or pv2) to write out the 4th row of tv2, 
      the section tv2(2:4, 4:8) and the section tv1(1:5:2) 
   (p_array.f90)

2. Look at the program status.f90, write down what you think will 
   be printed. Then run the program to compare. 

3. Write a program which uses an array of pointers (simulated
   by means of a derived type having a pointer component of the 
   desired type) to set up a lower-triangular matrix. (p_matrix.f90)

4. Run the program simple.f90, notice that the linked list 
   stores the typed-in numbers in reverse order. Modify this 
   program such that the linked list preserves the order of 
   typed-in numbers. (linklist.f90)

5. Run the program polyline.f90, which uses the polyline module 
   (poly_mod.f90), notice that the linked list stores the points 
   read in reverse order. When prompted for a yvalue enter the y value 
   of the point that you want to delete from the list. Compare the two 
   versions of the list that have been printed. Has your point been deleted?
   Modify this program such that the linked list preserves the order of 
   points read. (poly2.f90)