Exercises for Source form, Data Types and Control Structures
      ------------------------------------------------------------

Derived Types:
--------------

1.  Run the program vehicle.f90. What difference do you notice in the
    output of the two WRITE statements.

2.  Run the program circledef in circle.f90. Create a new derived type for
    a rectangle and assign and write out the corners of the rectangle.
    (rectdef.f90)

3.  Create a file circle.dat which contains the components of the
    centre and radius of a circle so that it can be read by program
    circledef2 (contained in circle2.f90).  Run the program.

4.  Alter program circledef4 (in circle4.f90) so that it prints a circle
    centred at the origin (0,0) with radius 4.0.

5.  Define a derived type that could be used to store a date of birth in
    the following type of format:

    15 May 1990

    Write a program to test your derived type in a similar manner to 
    the above examples. (birth1.f90)

6.  Modify the derived type in exercise 7 to include a component for a
    name. (birth2.f90)

Control Structure:
------------------

7.  Write a program containing a DO construct which reads numbers from
    the data file square.dat, skips negative numbers, adds the square
    root of positive numbers, and concludes if the present number is
    zero (use EXIT and CYCLE).  (sq_sum.f90)

8.  Write a program that reads in a month number (between 1 and 12) and
    a year number.  Use the CASE construct to assign the number of days
    for that month, taking leap years into account.  (no_days.f90)

9.  Write a program that reads in a character string.  Use the CASE
    construct in converting upper case characters to lower case and vice
    versa, and write out the new string.  Use IACHAR("a") - IACHAR("A")
    to determine the difference in the position in the collation
    sequence between lower and upper case characters.
    (convert.f90)

Kind Values:
------------

10. Run the program kind_int.f90.  Notice how this program uses
    SELECTED_INT_KIND to find the kind values for integer variable on
    this system.  Modify this program to find the kind values for real
    variables.  (kind_rl.f90)

11. Run the program mc_int.f90.  Notice how this program
    uses the kind values of integer variables found in exercise 1, and
    the numeric intrinsic functions to find some of the machine
    constants for this system.  Modify this program by using the kind
    values of real variables found in exercise 1 and the numeric
    intrinsic functions (PRECISION, HUGE, TINY and RANGE) to find some
    of the machine constants for this system.
    (mc_real.f90)