ITU Faculty of Aeronautics and Astronautics 01.06.2016

ITU Faculty of Aeronautics and Astronautics 01.06.2016 Department of Aeronautical Engineering 2015-2016 Fall Term 21949 DNK201E Introduction to Scientific and Engineering Computing (FORTRAN) Final Exam – SOLUTION

PROBLEM 1: (10p) Find the result of the following expressions.

(a) 1 / 2 * 0.0 (f) 3 ** 1 / 2 (b) 3.0 / 4 / 5 (g) (1 / 2) **3 (c) 2**1**3 (h) int(Log(10.0)) (d) 1 / 2**0.0 (i) exp(3 / 2.0) (e) 2.0 – 2.0 + 1 (j) "abc"(2:2)//"-"//"123"(2:2)

SOLUTION 1:

(a) 0.0 (f) 1 (b) 0.15 (g) 0 (c) 2 (h) 2 (d) 1.0 (i) 4.481689 (e) 1.0 (j) b-2

PROBLEM 2: (20p) What will be the output of each print statement in the following program? program problem_2 integer, dimension(2,3) :: a = reshape((/1,4,2,5,3,6/), (/2,3/)) integer, dimension(10) :: b = (/(i**2-i+1, i = 1, 10)/) integer :: i print "(3i3)", a(1,1:3), a(2,1:3) print "(2i3)", (a(1:2,i), i = 1,3) print "(4i3)", b(1:10:3) print "(5i3)", b(9:1:-2) end program problem_2

SOLUTION 2:

1 2 3 4 5 6 1 4 2 5 3 6 1 13 43 91 73 43 21 7 1

PROBLEM 3: (20p) The following program will exactly print ten lines. Write the output of the program. program problem_3 character(len=1), dimension(6) :: arr = (/"x", "t", "b", "z", "a", "k"/) character(len=1) :: temp integer :: i, j, n n = size(arr) do i = 1, n do j = i + 1, n if (arr(i)>arr(j)) then temp = arr(i) arr(i) = arr(j) arr(j) = temp print * , arr end if end do end do end program problem_3

SOLUTION 3: txbzak bxtzak axtzbk atxzbk abxztk abtzxk abkzxt abkxzt abktzx abktxz

PROBLEM 4: (20p) In the following code Jacobi iteration is applied for finding the root of the equation . The iteration converges when the criterion is satisfied. What will be displayed when the code is executed. program problem4 real :: x1, x2, eps = 0.01, root x1 = .75 do x2 = cos(x1) print *, x2 if (abs(x2-x1)

SOLUTION 4:

7.316889E-01 7.440471E-01 7.357336E-01 root of equation x - cos(x) = 0 is: 7.357336E-01

PROBLEM 5: (30p) A file named ‘scientists.dat’ contains the names of 100 scientists, each on a seperate line as shown in the figure below.

Isaac Newton Nikola Tesla Albert Einstein ...... Blaise Pascal

Write a single program that will read the records from this file (a) and save them to a new file called ‘namesort.dat’ sorted in alphabetical order according to names of the scientists, (b) sort the data according to surnames and save the data to a new file ‘surnamesort.dat’.

SOLUTION 5: program problem5 character(len=10), dimension(4) :: name, surname character(len=10) :: temp integer :: i, j open(10, file = "scientists.dat", status = "old", position = "rewind", action = "read", access = "sequential") do i = 1, 4 read(10,fmt = *) name(i), surname(i) end do do i = 1, 4 do j = i+1, 4 if (name(i)>name(j)) then temp = name(i) name(i) = name(j) name(j) = temp

temp = surname(i) surname(i) = surname(j) surname(j) = temp end if end do end do open(20, file = "namesort.dat", status = "unknown", position = "rewind", action = "write", access = "sequential") write(20, fmt = "(2a)") (name(i), surname(i), i =1,4) do i = 1, 4 do j = i+1, 4 if (surname(i)>surname(j)) then temp = name(i) name(i) = name(j) name(j) = temp

temp = surname(i) surname(i) = surname(j) surname(j) = temp end if end do end do open(30, file = "surnamesort.dat", status = "unknown", position = "rewind", action = "write", access = "sequential") write(30, fmt = "(2a)") (name(i), surname(i), i =1,4) end program problem5