1.1
A/B*C = 9
A*B/C = 4
3*A**B = 108
B+A/C = 4
A/B+C = 6

1.2
A/B*C = 0
A*B/C = 3
3*A**B = 729
B+A/C = 5
A/B+C = 4

1.3 program
PROGRAM Trivial
    INTEGER :: A, B, C
    A = 6
    B = 2
    C = 3
    PRINT *, A/B*C, A*B/C, 3*A**B, B+A/C, A/B+C
    A = 3
    B = 5
    C = 4
    PRINT *, A/B*C, A*B/C, 3*A**B, B+A/C, A/B+C
END PROGRAM Trivial

1.3 output
 9 4 108 4 6
 0 3 729 5 4

2.1
20.0
1.0
0.0

2.2
20
1
1

3.1
Division by zero.
Overflow.
Underflow.

Programs containing such expressions may crash, may deliver a special
value or may otherwise misbehave. In general, underflow will cause the
result to be quietly replaced by zero, but that is not required by the
Fortran standard.

4.1
a) Why are named constants useful?

Answer: They reduce mistyping errors, they makes it clearer which
constant is being used and they make it easier to modify the program
later.

b) What is the difference between

REAL, PARAMETER :: pi = 22.0/3.0
and

REAL :: pi = 22.0/3.0

Answer: The first defines a named constant pi with value 22.0/3.0, the
second declares a variable named pi initialised to 22.0/3.0.

c) Is the following program fragment allowed?

INTEGER, PARAMETER :: ZERO = 0
ZERO = 1

Answer: No, because ZERO is a constant and cannot be changed.


d) Is the following program fragment allowed?

INTEGER :: ONE = 1
ONE = 0

Answer: Yes, since ONE is a variable. It can have any value.

6.1
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

Correct, but quirky.

b) CHARACTER :: name

Correct.

c) CHARACTER(LEN=10) :: name

Correct.

d) REAL :: var-1

INCORRECT - you can't declare an expression.

e) INTEGER :: 1a

INCORRECT - names must start with a letter.

f) INTEGRAL :: loji

INCORRECT - there is no statement 'INTEGRAL'.

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

Correct, but town will contain "Glasg".

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

Correct.

i) INTEGER :: pi = +22/7

Correct, but not useful - the value of pi will be 3.

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

INCORRECT - no constant name was given.

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

Correct.

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

Correct, provided pye is defined previously as a PARAMETER.

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

Correct, but it is not good practice.

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

INCORRECT - that is a mangled character constant.

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

Correct.

p) INTEGER :: ia ib ic id 

INCORRECT - you can't separate lists by spaces.

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

Either - atan is not allowed in initialisation in Fortran 95, but
is in Fortran 2003.

Declare the following objects:

a) feet an integer variable

INTEGER :: feet

b) miles a real variable

REAL :: miles

c) Town a character variable of up to 20 letters

CHARACTER(LEN=20) :: Town

d) home_town a constant with value set to LIVERPOOL

CHARACTER(LEN=*) :: home_town = "LIVERPOOL"

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

REAL, PARAMETER :: sin_half = 0.47942554
or, in Fortran 2003:
REAL, PARAMETER :: sin_half = sin(0.5)

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?

False. IMPLICIT NONE forces all variables to be declared in type
statements.

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

Answer: ( ( ( (-(a*b)) - (c/(d**e))/f ) + (g**h) ) + 1 ) - (j/k)
3 2 1 x x y y 1 2 3

8.1 program
PROGRAM sample
    IMPLICIT NONE
    CHARACTER(LEN=40) :: name
    CHARACTER(LEN=20) :: date
    PRINT *, 'Type name'
    READ *, name
    PRINT *, 'Type date'
    READ *, date
    PRINT *, trim(date) // ' is the birthday of ' // name
END PROGRAM sample

8.2 program
PROGRAM sample
    IMPLICIT NONE
    CHARACTER(LEN=40) :: name
    CHARACTER(LEN=20) :: date
    PRINT *, 'Type name'
    READ *, name
    PRINT *, 'Type date'
    READ *, date
    PRINT *, trim(name) // ' was born on ' // date
END PROGRAM sample

9.1 program
PROGRAM Area
    IMPLICIT NONE
    REAL :: radius
    REAL, PARAMETER :: pi = 3.14159
    PRINT *, "Type in the radius"
    READ *, radius
    PRINT *, "Area of circle with radius ", &
        radius, " is ", pi*radius**2
    PRINT *, "Volume of sphere with radius ", &
      radius, " is ", (4.0/3.0)*3.14159*radius**3
END PROGRAM Area

9.1 answers
 Type in the radius
    2
 Area of circle with radius    2.0000000  is   12.5663605
 Volume of sphere with radius    2.0000000  is   33.5102959
 Type in the radius
    5
 Area of circle with radius    5.0000000  is   78.5397491
 Volume of sphere with radius    5.0000000  is    5.2359839E+02
 Type in the radius
    10
 Area of circle with radius   10.0000000  is    3.1415900E+02
 Volume of sphere with radius   10.0000000  is    4.1887871E+03