BASIC MATLAB TUTORIAL: PART 3

Its the part 3 of my BASIC MATLAB TUTORIAL.

1.How to display any statements ?  For that we will use the ” disp() “function. Anything we write on the display fuction gets displayed. Eg.

>> disp('My name is Mousam Choudhury')
My name is Mousam Choudhury
>> a=magic(2);
>> disp(a)
1      3
4      2

2.How to see a particular Row of matrix or a particular column of a matrix? For it we will use the colon symbol : ” .

if we want to see all the row values of a particular matrix , then we put colon on the row part and the column no. on the column part. See below

>> a=magic(4)

a =

16     2     3     13
5     11    10      8
9      7     6     12
4     14    15      1

>> disp('see 2nd column and all row values')
see 2nd column and all row values
>> a(:,2) # 1st part is row and 2nd part is column

ans =

2
11
7
14
>> disp('see 4th column and all row values')
see 4th column and all row values
>> a(:,4)

ans =

13
8
12
1

To see all the column values of a particular row , then put colon on the column part and the row no. on the row part

>> disp('see 3rd row and all column values')
see 3rd row and all column values
>> a(3,:)

ans =

9   7   6   12

To see a particular value of a row and column , then just replace the row and column part with that value. Eg.

>> disp('see 3rd row and 4th column values')
see 3rd row and 4th column values
>> a(3,4)

ans =

12

>> disp('see 2nd row and 2nd column values')
see 2nd row and 2nd column values
>> a(2,2)

ans =

11

3.How to distribute a range in step? For this we need the minimum value , the step size and the maximum value. See the below examples:

>> disp('DISTRIBUTE A RANGE BETWEEN 1 TO 4 IN STEP SIZE 0.5')
DISTRIBUTE A RANGE BETWEEN 1 TO 4 IN STEP SIZE 0.5
>> distribute_a_range=1:0.5:4

distribute_a_range =

1.0000    1.5000    2.0000    2.5000    3.0000    3.5000    4.0000
>> disp('DISTRIBUTE A RANGE BETWEEN 11 TO 14 IN STEP SIZE 1')
DISTRIBUTE A RANGE BETWEEN 11 TO 14 IN STEP SIZE 1
>> distribute_a_range=11:1:14

distribute_a_range =

11   12   13   14

So by changing the step size

4.How to make a column matrix from a normal (row x column) matrix ?  Suppose i want to make a 3*3 matrix into a column matrix having the values from the 3*3 matrix, we can use the following method. Its basically using the “:” symbol again. See the below examples.

>> a=[1 2 3;4 5 6;7 8 9]

a =

1   2   3
4   5   6
7   8   9

>> a_column=a(:)

a_column =

1
4
7
2
5
8
3
6
9

As you can see the value were taken column after column i.e. 2nd columnwas added after 1st coulmn and the 3rd column after the second.

In order to get the values row wise, we have to use the following tweak. See below.

>> a_RowWise_column=reshape(a.',[],1)

a_RowWise_column =

1
2
3
4
5
6
7
8
9

Note: Use the variable names in such a way that they represent the operation which you are doing. like the above one, “a_RowWise_column” , because i am taking the values row wise but the output is a column matrix of those values.

5.Can we get back the original matrix from the column matrix? Yes , we can. Just see the code to do so below.

>> a_original=reshape(a_column,3,3)

a_original =

1   2   3
4   5   6
7   8   9

NOTE: “reshape” is an in built function. Read more about it in the MATLAB help section. Since the original matrix was 3*3 , so i wrote 3,3 in the parenthesis.

LET US SEE ANOTHER EXAMPLE

MAKE A 4*4 MATRIX

>> a=[1 2 3 4;5 6 7 8;9 10 11 12;13 14 15 16]

a =

1    2    3    4
5    6    7    8
9   10   11   12
13  14   15   16

MAKE A COLUMN MATRIX OF THE ABOVE 4*4 MATRIX

>> a_column=a(:)

a_column =

1
5
9
13
2
6
10
14
3
7
11
15
4
8
12
16

MAKE THE ORIGINAL MATRIX FROM THE ABOVE COLUMN MATRIX

>> a_original=reshape(a_column,4,4)

a_original =

1    2    3    4
5    6    7    8
9   10   11   12
13  14   15   16

 

THANK YOU FOR READING AND ENCOURAGING ME TO CONTRIBUTE THE KNOWLEDGE THAT I HAVE. 

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