Introduction to Programming with Fortran
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Practical Exercise 3
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Question 1
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1.1 Evaluate the following when A = 6, B = 2 and C = 3.  A, B and C are
all integer variables.

    A/B*C
    A*B/C
    3*A**B
    B+A/C
    A/B+C


1.2 Evaluate the above expressions when A = 3, B = 5 and C = 4.


1.3 Write a program to check that your Fortran compiler gives the
results you have given.


Question 2
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2.1 What value does the real variable A take in the following statements
when I = 5, J = 4 and K = 3 (I, J and K are INTEGER)?

    A = I*J + 1/K
    A = I/J + 1/K
    A = J/I + 1/K


2.2 What value does the INTEGER I take in the following statements when
A = 5.0, B = 4.0 and C = 3.0 (A, B and C are REAL)?

    I = A*B + 1/C
    I = A/B + 1/C
    I = B/A + 1/C


Question 3
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3.1 On a particular computer the range for reals is 10^-38 to 10^+38.

a) What value does the expression (A/B) have when A = 1.0, B = 0.0?

b) What value does the expression (5.3E+25 * 6.4E+28) have?

c) What value does the expression (5.3E-50 * 6.4E-35) have?


Question 4
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4.1 This question is about named constants.

a) Why are named constants useful?

b) What is the difference between

    REAL, PARAMETER :: pi = 22.0/3.0
and

    REAL :: pi = 22.0/3.0

c) Is the following program fragment allowed?

    INTEGER, PARAMETER :: ZERO = 0
    ZERO = 1

d) Is the following program fragment allowed?

    INTEGER :: ONE = 1
    ONE = 0


Question 5
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5.1 Which of the following are incorrect declarations and why?  If you
think a declaration may be correct in a given situation (but not
everywhere) then say what the situation would be.

a) ReAl :: x

b) CHARACTER :: name

c) CHARACTER(LEN=10) :: name

d) REAL :: var-1

e) INTEGER :: 1a

f) INTEGRAL :: loji

g) CHARACTER(LEN=5) :: town = "Glasgow"

h) CHARACTER(LEN=*), PARAMETER :: city = "Glasgow"

i) INTEGER :: pi = +22/7

j) CHARACTER(LEN=*), PARAMETER :: "Bognor"

k) REAL, PARAMETER :: pye = 22.0/7.0

l) REAL, PARAMETER :: two_pie = pye*2

m) REAL :: a = 1., b = 2

n) CHARACTER(LEN=6) :: you_know = 'y'know"

o) CHARACTER(LEN=6) :: you_know = "y'know"

p) INTEGER :: ia ib ic id 

q) REAL :: poie = 4.*atan(1.)


Question 6
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6.1 Declare the following objects:

a) feet         an integer variable

b) miles        a real variable

c) Town         a character variable of up to 20 letters

d) home_town    a constant with value set to LIVERPOOL

e) sin_half     a constant with value set to sin(0.5) = 0.47942554


Question 7
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7.1 When IMPLICIT NONE is used at the start of a program all variable
names beginning with I, J, K, L, M, N are assumed to be INTEGER.  Is
this true or false?


7.2 Add parentheses to the following expression to indicate the order of
evaluation:

    -a*b-c/d**e/f+g**h+1-j/k


Question 8
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8.1 Write a program that reads in a person's name and date of birth (in
the form `dd.mm.yy') and prints out a sentence such as:

    dd.mm.yy is the birthday of Joe Bloggs


8.2 Modify the program to print the sentence in the form:

    Joe Bloggs was born on dd.mm.yy


Question 9
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9.1 Write a simple program to read in a radius and calculate the area of
the corresponding circle and volume of the corresponding sphere.
Demonstrate its correctness by calculating the area and volume using
radii of 2, 5 and 10.

The area of a circle is pi times the radius squared, and pi may be taken
as 3.14159.  The volume of a sphere is 4/3 pi times the radius cubed.