Cursera: Machine Learning Exercises 1 Accomplished.

machine_learning/test.m

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+%VIM: let g:flags=""
+%
+a = 3
+b = 'hi'
+b
+a = pi
+c = (3 >= 1 )
+disp(sprintf('2 decimals: %0.2f', a ))
+format long
+a
+format short
+a
+
+A = [1 2; 3 4; 5 6] % define matrix
+v = [1 2 3]		% row vector
+v = [1; 2; 3]	% column vector
+v = 1:0.2:2		% vector from 1 to 2 with 0.2 increments
+v = 1:6			% vector 1 to 6
+
+ones(2,3)		% matrix of ones
+2*ones(2,3) 
+zeros(3,1)		% matrix of zeros
+eye(4)			% identity matrix
+rand(2,3)		% matrix of random numbers
+randn(2,3)		% matrix of normal distribution random numbers
+
+w = -6 + sqrt(10)*randn(1,10000)
+
+hist(w,50)		% histogram
+
+size(A)			% sizes of matrix as a row vector
+size(A,1)		% number of rows
+size(A,2)		% number of columns
+length(v)		% length of a matrix
+
+%load( 'file name' ) % load data from a file
+
+who				% what variables do I have.
+whos			% detailed who
+
+%v = priceY(1:10)
+%save savedfile.mat v
+%save savedfile.mat v -ascii
+
+clear			% remove variables
+
+A = [1 2; 3 4; 5 6 ]
+A(3,2)			% element on third row  and second column
+A(3,:)			% third row
+A(:,2)			% second column
+
+A([1 3], :)		% matrix from 1 and 3 rows
+A(:,2) = [10; 11; 12]	% assign to second column
+A = [A, [100; 101; 102]] % append to matrix
+
+B = [ 3 3; 5 6; 6 7]
+
+C = [ A B ]		% append to the right
+D = [ A; B ]	% append at bottom
+
+A'				% transpos
+A * B'			% matrix mul
+A .* B			% element vice mult
+A .^2			% element vice square
+
+v = [ 1; 2; 3 ]
+
+1 ./ v			% reciprocal of v
+1 ./ A
+
+log(v)			% element vice log
+exp(v)
+abs(v)
+-v
+v + ones(lenght(v), 1)
+v + 1			% same as of above
+
+a = [2 3 4 5]
+max(a)			% max element in a
+[val, ind] = max(a)	% val = max elem, ind = the index of elem
+
+
+a < 3			% elem vice compare
+find(a < 3)
+
+A = magic(3)
+
+[r,c] = find(A>=7)
+
+sum(a)
+prod(a)
+floor(a)
+ceil(a)
+
+max( rand(3), rand(3) ) % elem vice max of two 3x3 matrices
+
+max ( A, [], 1 )	% row vice max
+max(A)				% column vice max
+
+A = magic(9)
+
+sum(A,1)
+
+A .* eye(9)
+
+sum( sum( A.*eye(9))) % sum of diagonal elements
+
+flipud( eye(9))		%flip up down
+
+pinv(A)				%pseudo inverse of A
+
+
+%============================
+t=[0:0.01:0.98];
+y1 = sin(2*pi*4*t)
+plot(t,y1);
+y2 = cos(2*pi*4*t)
+plot(t,y1);
+hold on;
+plot(t,y1,r);
+xlabel('time')
+ylabel('value')
+legend('sin','cos')
+title('my plot')
+print -dpng 'myPlot.png'
+close
+
+
+figure(1); plot(t,y1);
+figure(2); plot(t,y2);
+subplot(1,2,1);
+axis
+
+A= magic(5);
+imagesc(A);
+imagesc(A),colorbar,colormap gray;
+
+%============================
+v = zero(10,1)
+for i=1:10,
+	v(i) = 2^i;
+end;
+while i <= 5,
+	v(i) = 100;
+	i = i+1;
+	if i == 4,  %elseif else
+		break;
+	end;
+end;
+
+%put into a separate file with the same name
+function y = functionName( x )
+ y = x^2;
+
+function [y1,y2] = functionName( x )
+ y1 = x^2;
+ y2 = x^3;
+
+
+
+
+
+%help eye
+