Octave

Commands

• % means comment
• ; suppresses print output
• 2^6(2 power 6)
• 1==2
• 1~=2 (is not equals)
• Logical operations
•  1&&0
• 1||0
•  Vectors & Matrix
• A=[1 2; 2 3; 4 5]
• V=1:0.2:2  % Bunch of elements starts from 1, increments with 0.2, until you get up to 2
• V=1:6  %means 1 to 6
• ones(2,3)   % 2 by 3 matrix with all elements as 1
• use try zeros, rand
• w=-6+sqrt(10)*(randn(1,10000))
  hist(w)     % generates histogram
  hist(w,50) % histogram with 50 bins
• I= eye(4)     % 4*4 identity matrix
• A(2,:) % to fetch every element of 2nd row 
• A(:,2)  % 2nd column
• A([1,3],:) % every element in 1st and 3rd rows
• A=[A,[100;102;102]]  % append another column vector
• A(:)  % put all elements of A into single vector
• C=[A B] % concatenate 2 matrices
• C=[A; B] % concatenate 2 matrices by adding B to bottom of A
• A .* B  %element wise multiplication
• A .^ 2  %element wise square
• 1 ./A %element wise reciprocal
• A'   % transpose
• Octave variables in memory
• who/whos
• load
• load featuresx.dat  %featuresx will be variable after loading
• clear featuresx % to clear the variable
• save hello.mat v % to save varaible v to hello.mat
• clear   % clears all variables
• Function
• file extension .m
• function y= squareThisNumber(x)
  y=x^2;
• Octave searches for the file in the current directory
• Alternatively add path using command addpath();
• Octave function can return more than one value
•