Added MATLAB as a new language

matlab.html.markdown

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+---
+language: Matlab
+contributors:
+    - ["mendozao", "http://github.com/mendozao"]
+---
+
+Matlab stands for Matrix Laboratory. It is a powerful numerical computing language commonly used in engineering and mathematics.  
+
+If you have any feedback please feel free to reach me at
+[@the_ozzinator](https://twitter.com/the_ozzinator), or
+[osvaldo.t.mendoza@gmail.com](mailto:osvaldo.t.mendoza@gmail.com).
+
+```Matlab
+
+
+
+% Comments start with a percent sign.
+
+%{ Multi line comments look 
+something
+like
+this %}
+
+clear % Erases all your variables from memory
+clc % Erases the writing on your Command Window
+who % Displays all variables in memory
+diary % History of session
+ctrl-c % Abort current computation
+
+help command % Displays documentation for command in Command Window
+lookfor command % Searches for a given command
+
+
+% Output formatting
+format short % 4 decimals in a floating number
+format long % 15 decimals
+fprintf 
+
+% Variables & Expressions
+myVariable = 4 % Notice Workspace pane shows newly created variable
+myVariable = 4; % Semi colon suppresses output to the Command Window
+4 + 6  % ans = 10 
+8 * myVariable % ans = 32 
+a = 2; b = 3; 
+c = exp(a)*sin(pi/2) % c = 7.3891
+
+% Logicals
+1 > 5 % ans = 0
+10 >= 10 % ans = 1
+3 ~= 4 % Not equal to -> ans = 1
+3 == 3 % equal to -> ans = 1
+3 > 1 && 4 > 1 % AND -> ans = 1
+3 > 1 || 4 > 1 % OR -> ans = 1
+~1 % NOT -> ans = 0
+
+% Strings
+a = 'MyString'
+length(a) % ans = 8
+a(2) % ans = y
+[a,a] % ans = MyStringMyString
+
+
+% Cells
+a = {'one', 'two', 'three'} 
+a(1) % ans = 'one' - returns a cell
+char(a(1)) % ans = one - returns a string
+
+
+% Vectors
+x = [4 32 53 7 1] 
+x(2) % ans = 32, indices in Matlab start 1, not 0
+x(2:3) % ans = 32 53
+x(2:end) % ans = 32 53 7 1
+
+x = [4; 32; 53; 7; 1] % Column vector
+
+x = [1:10] % x = 1 2 3 4 5 6 7 8 9 10
+
+% Matrices
+A = [1 2 3; 4 5 6; 7 8 9] 
+% Rows are seperated with a semi colon, each element is seperated with space or comma
+% A =
+
+%     1     2     3
+%     4     5     6
+%     7     8     9
+
+A(2,3) % ans = 6, A(row, column)
+A(2,3) = 42 % Update row 2 col 3 with 42
+% A =
+
+%     1     2     3
+%     4     5     42
+%     7     8     9
+
+A(2:3,2:3) % Creates a new matrix from the old one
+%ans =
+
+%     5     42
+%     8     9
+
+A(:,1) % All rows in column 1
+%ans =
+
+%     1
+%     4
+%     7
+
+A(1,:) % All columns in row 1
+%ans =
+
+%     1     2     3
+
+A(:, [3 1 2]) %Rearrange the columns of original matrix
+%ans =
+
+%     3     1     2
+%    42     4     5
+%     9     7     8
+
+A(1, :) =[] %Delete the first row of the matrix
+
+size(A) % ans = 3 3
+
+A' % Transpose the matrix
+
+[A ; A] % Concatenation of matrices
+%ans =
+
+%     1     2     3
+%     4     5    42
+%     7     8     9
+%     1     2     3
+%     4     5    42
+%     7     8     9
+
+
+%Element by Element Arithmetic VS Matrix Arithmetic 
+A * B % Matrix multiplication
+A .* B % Multiple each element in A by its corresponding element in B
+
+
+%Plotting
+x = 0:.10:2*pi % Creates a vector that starts at 0 and ends at 2*pi with increments of .1
+y = sin(x)
+plot(x,y)
+xlabel('x axis')
+ylabel('y axis')
+title('Plot of y = sin(x)')
+axis([0 2*pi -1 1]) % x range from 0 to 2*pi, y range from -1 to 1
+plot(x,y1,’-’,x,y2,’--’,x,y3,’:’) % For multiple functions on one plot
+
+
+% .mat files
+% Save the variables in your Workspace 
+
+%M-file Scripts
+%A script file is an external file that contains a sequence of statements.
+%Better than typing your code in the Command Window
+%Have .m extensions
+
+
+%M-file Functions
+%Programs that accept inputs and return an output
+%Have .m extensions
+% double_input.m - naming your ,m file the same as you call it in the file is required
+function output = double_input(x) 
+	%double_input(x) returns twice the value of x
+	output = 2*x;
+end
+double_input(6) % ans = 12 
+
+%User input
+a = input('Enter the value: ')
+
+%Reading in data
+fopen(filename) 
+
+%Output
+disp(a) % Print out the value of variable a
+disp('Hello World') % Print out a string
+fprintf % More control display to Command Window 
+
+%Conditional statements
+if a > 15
+	disp('Greater than 15')
+elseif a == 23
+	disp('a is 23')
+else
+	disp('neither condition met')
+end
+
+%Looping
+for k = 1:5
+	disp(k)
+end
+	
+k = 0;	
+while (k < 5)
+	k = k + 1;
+end
+
+
+%Connecting to a MySQL Database
+dbname = 'database_name';
+username = 'root';
+password = 'root';
+driver = 'com.mysql.jdbc.Driver';
+dburl = ['jdbc:mysql://localhost:8889/' dbname];
+javaclasspath('mysql-connector-java-5.1.xx-bin.jar'); %xx depends on version, download available at http://dev.mysql.com/downloads/connector/j/
+conn = database(dbname, username, password, driver, dburl); 
+sql = ['SELECT * from table_name where id = 22'] %Example sql statement
+a = fetch(conn, sql) %a will contain your data
+
+
+% Common math functions
+sin(x)
+cos(x)
+tan(x)
+asin(x)
+acos(x)
+atan(x)
+exp(x) 
+sqrt(x)
+log(x)
+log10(x)
+abs(x)
+min(x)
+max(x)
+ceil(x)
+floor(x)
+round(x)
+rem(x)
+rand
+randi
+
+% Common constants
+pi
+NaN
+inf
+
+% Common matrix functions
+zeros(m,n) % m x n matrix of 0's
+ones(m,n) % m x n matrix of 1's
+diag(A) % Extracts the diagonal elements of a matrix 
+eye(m,n) % Indentity matrix
+inv(A) % Inverse of matrix A
+det(A) % Determinant of A
+eig(A) %Eigenvalues and eigenvectors of A
+isempty(A) % Tests if array is empty
+isequal(A, B) %Tests equality of two arrays
+numel(A) %Number of elements in matrix
+
+
+
+```
+
+## More on Matlab
+
+* The official website [http://http://www.mathworks.com/products/matlab/](http://www.mathworks.com/products/matlab/)