# learning basics of Matlab

#### PG1995

Joined Apr 15, 2011
819
Hi

I have just installed Matlab and need your help to learn the basics.

I have some experience with C++ and have written some basic programs such as adding two matrices etc. C++ provides an interaction between a user and a computer. In other words, suppose you write down a program for addition of two 2x2 matrices, and when it's run it asks the user to enter the elements of both matrices, once we are done with entering the elements, it will pop up the resultant matrix. The way my instructor, who himself is quite new to Matlab, was showing the running of Matlab it looked like Matlab doesn't provide the interaction. Do there exist things like "cin" and "cout" in Matlab? If I'm wrong, then could you please give me some simple program for addition of two 2x2 matrices so that I can play around and learn it? Thank you.

Regards
PG

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#### panic mode

Joined Oct 10, 2011
1,919
Rich (BB code):
%% have following three lines at top of each matlab program
clc;
clear all;
close all;

rows=input('Number of matrix rows:');
cols=input('Number of matrix columns:');

% get elements of matrix A
for x=1:rows
for y=1:cols
A(x,y)=input(strcat('A(',num2str(x),',',num2str(y),')='));
end
end

disp(' '); % just line break

% get elements of matrix B
for x=1:rows
for y=1:cols
B(x,y)=input(strcat('B(',num2str(x),',',num2str(y),')='));
end
end

disp(' '); % line break

disp(C); % display result

notes:

1. line can but does not have to end with semicolon, semicolon just hides output of that line
2. comments are % and %%
3. there is TONS of tutorials and code samples online
4. always write code in Editor, if you need to test it use breakpoints and stepping through
5. good idea is to clear everything at begin of each file (clear all variables, remove all graphs, etc.)

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#### panic mode

Joined Oct 10, 2011
1,919
6. strings are enclosed in single quotes
7. converting number to string is through num2str
8. concatenating strings is done through strcat('abc', 'def','ghijkl');
9. transposed matrix is indicated by apostrophe such as C=A'+B'
10. unless specified, operations are matrix operations. for example multiplication etc. if needed to perform element to element operation, append dot after operator. for example

C=A*B is matrix multiplication
D=A*.B is element to element scalar multiplication

#### MrChips

Joined Oct 2, 2009
24,651
Matlab can be used in the command mode or in the script mode.
In command mode, to create a 2 x 2 matrix, just enter something like:

a = [ 1 2 ; 3 4 ]

and this creates:

a =

1 2
3 4

if you want to display the matrix again, just type

a

You can do the same for b:

b = [ 5 6 ; 7 8 ]