2015S001/User talk:Mzevallos/Homework 7

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Important: Write out your answers by hand before checking them with MATLAB!

Contents

  1. For loop basic pattern
  2. For loop basic pattern
  3. For loop general pattern
  4. Arrays with a for loop
  5. Arrays with a for loop
  6. Iteration
  7. Iteration
  8. nested for-loops
  9. nested for loops
  10. Interpreting a Loop V
  11. Nested for loop

1. For loop basic pattern

y = 10;
y = y+37;
y = y + 2;
y = y + 2;
y = y + 2;
y = y + 2;
y = y + 2;
y = y + 2;
y = y + 5;
y = y + 99;






Identify the parts of the program that are repeated and hence a candidate for short-hand. Write a new version of the full program to the left using a for loop to reduce the length of the program.

please give me an example, or help me solve this one, I don't understand what it's asking.

There are office hours and email availabilities.

2. For loop basic pattern

a = 0;
z = a+1;
a = z+1;
q = a+z;
z = a+1;
a = z+1;
q = a+z; 
z = a+1;
a = z+1;
q = 2*q;


Identify the parts of this program that are repeated. Write a shorter version of the program to the left using a for loop.

No answer provided.

3. For loop general pattern

i = 1;
a = 13;
i = 2;
a = i*i;
i = 3;
a = i*i;
i = 4;
a = i*i;
a = 2*a;


What is the final value of a? Write a short-hand version of the program to the left using a for loop. The final value of ashould be the same as the value obtained when running the long-hand version.

No answer provided.

4. Arrays with a for loop

clear;
c=1;
for x=[1:4];
  B(x) = x;
end
B



What does the resulting array look like?

B =

    1     2     3     4     4

The second 4 should not be there.

5. Arrays with a for loop

clear;
c=1;
for x=[1:4];
  c = c+1; 
  B(c) = x;
end
B


What does the resulting array look like?

B =

    0     1     2     3     4

6. Iteration

Write down the values of A(2), A(3), A(4), and A(5) after this loop has executed.

A(1) = 3
for i = [2,3,4,5]
  A(i) = i*A(i-1)+i*i
end

A(2)= 10

A(3)= 39

A(4)= 172

A(5)= 885

7. Iteration

Create a variable called result. Assign it a value of zero. Then create a FOR loop such that when completed, the variable result holds the value of the sum 12 + 22 + 32 + ... + 10002

result=0

for i=[1:1000].^2

sum(i)

result=result+i

end

8. nested for-loops

Using a set of nested for loops, create the following matrix

M =

   11    12    13    14    15
   16    17    18    19    20
   21    22    23    24    25
   26    27    28    29    30
   31    32    33    34    35

a=[11:1:35]

for i=[1:5]

for j = [1:5]

a(i,j) = 1

variable = variable+1

end

end

This does not create the correct matrix.

9. nested for loops

Using a set of nested for loops and one or more if statements, modify the matrix above so that all values along the diagonal are zero.

M =

    0    12    13    14    15
   16     0    18    19    20
   21    22     0    24    25
   26    27    28     0    30
   31    32    33    34     0

M = [11:15;16:20;21:25;26:30;31:35]

for i = [1:5]

for j = [1:5]

i=j

M(i,j)=0;

end

end

10. Interpreting a Loop V

What are the values in the matrix M after executing this program?

for j = [-1:1]
  for i = [0:1]
    M(i+1,j+2) = j;
  end
 end
M

M =

   -1     0     1
   -1     0     1

11. Nested for loop

Using MATLAB, do the following procedure:

Download the Data file to your directory, name it as hw7.dat, and load it into your MATLAB session by: >> load hw7;

check what variables (i.e., arrays) are defined in this data file by running: >> whos

Now, applying double nested for-loops to calculate the total sum of all the elements contained in the matrix. Provide both the code and the final answer.

No answer provided.

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