commit msg

1_Introduction/introduction.m

@@ -20,7 +20,7 @@
 % Press F5 to run entire scripts
 
 % Sections
-% Type double-percent signs to mark sections
+% Type double-percent signs to mark sections: -> %%
 % Partition code for readability,
 % run current section with ctrl + enter
 disp('hello')
@@ -44,22 +44,21 @@ z = x + y;
 % We can also make an empty variable:
 a = [];
 
-% Workspace:
-% Stores temporary data
+% Workspace: Stores temporary data
 
 % vectors
 v = [1; 2; 3];
 w = [1, 2, 3];
 
 % vectors with linear spacing, both these methods generate row vectors
-% use ful when we define grids for dynamic programming
+% useful when we define grids for dynamic programming
 v = 1:0.5:100;           % <- from 1 to 100, taking steps of 1/2
 w = linspace(1,100,200); % <- from 1 to 100, generating 200 steps
 
 % logarithmic spacing:
 u = logspace(0,2,200);  % <- from 10^0 to 10^2, generating 200 steps
 
-% help logspace
+% type help to get information about matlab commands: help logspace
 
 % transpose
 v = v';
@@ -86,11 +85,11 @@ title('Plotting vectors')
 L = legend('1:0.5:100', 'linspace', 'logspace');
 L.Location = 'northwest';
 
-yyaxis right
+yyaxis right % <- using two axes in one plot is sometimes useful
 plot(1./u)
 
 
-% Variable editor
+%% Variable editor
 
 % Clean-up:
 % removing variables: clear
@@ -119,7 +118,7 @@ C = [A; B];
 % Horizontally
 D = [A B];
 
-% Very useful tool, repmat:
+% Very useful tool, repmat: Repeats matrices a specified number of times
 A = eye(2);
 B = repmat(A, 5, 2);
 
@@ -136,8 +135,8 @@ y = linspace(-10, 10, 10)';
 [X,Y] = meshgrid(x,y);
 
 % Its use might not be obvious right now, but consider a function
-% of one variable f(x). Its convenient to use a vector for x here, so
-% that we may evaluate f for all values of x in one go. Similarly if
+% of one variable f(x). It's convenient to use a vector for x here, so
+% that we may evaluate f for all values of x in one go. Similarly, if
 % f is a function of two variables x and y, we can evaluate f on the entire domain
 % at once using X and Y from meshgrid. Example (we will return to functions
 % and plotting shortly)
@@ -185,6 +184,7 @@ max(A)        % maximum element of each column (default)
 max(A,1)      % compares each entry to 1 and takes the maximum, does not give maximum of column one
 max(A, [], 1) % maximum element of each column
 max(A, [], 2) % maximum element of each row
+max(max(A))   % maximum element in the matrix
 
 % different functions applied to matrices works similarly
 % but take nothing for granted, check that matlab does what you
@@ -198,7 +198,7 @@ sum(sum(A)) % sum of all elements
 
 % Adding matrices is clear:
 % Adding matrices of wrong sizes will not work
-% "Matrix dimensions must agree." - Matlab motto
+% "Matrix dimensions must agree." - Common matlab error
 A = eye(2);
 B = eye(3);
 C = A + B;
@@ -245,7 +245,7 @@ C = A .* v;
 % Matrix inverses
 D = diag([1,2,3]);
 A = inv(D); % Inverse (usually not recommended)
-A = D \ eye(3);  % Produces the same result, but superior numerics
+A = D \ eye(3);  % Produces the same result, but superior numerically
 
 
 %% Special variables
@@ -273,7 +273,7 @@ l1 = 1;
 l2 = 2;
 l3 = 3;
 
-% check their sum...
+% check their sum... L = 6?
 L = l1 + 12 + 13;
 
 
@@ -288,7 +288,9 @@ x=3;
 longName = 5;
 x        = 3;
 
-% ctrl + I is a nice shortcut
+% ctrl + I is a nice shortcut to format code:
+% Mess up the formatting in the loop below. Then highlight it and press
+% ctrl + I
 for j = 1:length(x)
     if j < 3
         y = 4;

2_Indexing/indexing.m

@@ -67,7 +67,7 @@ max(A, [], 2) % maximum element of each row
 v = linspace(1,10,10);
 [~,idx] = max(v);
 
-% We can use find to ... find certain elements in a vector or matrix
+% We can use find() to find certain elements in a vector or matrix
 % no extra inputs finds nonzero elements, for v, all elements are nonzero
 idx = find(v);
 
@@ -86,7 +86,7 @@ v = [1, 2, inf];
 idx = isinf(v); % returns a logical vector of inf-locations (not the same as earlier)
 v(idx);         % but we can use it the same way, to find elements that are = inf
 
-% we also have isnan etc.
+% we also have isnan, etc.
 
 % Another example: any() and all()
 % will return true if any element of v is true (or non-zero)
@@ -94,13 +94,13 @@ any( 0 )     % returns false
 any([0,1])     % returns true 
 
 % all() works the other way around, it requires that all elements are true
-all(0)     % returns falce
+all(0)     % returns false
 all([0,1]) % returns false
 
 % These are useful to check vectors in if-statements. Its easy to make the
 % mistake here
 
-% if we compare a vector to a scalar, we check for each element
+% Common mistake: if we compare a vector to a scalar, we check for each element
 v = [0;1];
 v >= 1 
 
@@ -118,7 +118,7 @@ if any(v) >= 1
     disp('hello world')
 end
 
-% or equivalently
+% or equivalently, v(1) >= 1 OR v(2) >= 1
 if v(1) >= 1 || v(2) >= 1
     disp('hello world')
 end

3_functions/functionScript.m

@@ -27,7 +27,7 @@ f(y)
 % we can define more function handles
 g = @(x) x + 1;
 
-% unfortunately, this does not work
+% How about adding functions? unfortunately, this does not work
 h = f + g;
 
 % but this does
@@ -41,7 +41,7 @@ clearvars -except h
 % and attempt to evaluate h(3)
 h(3)
 
-% it works. the function h remembers what f and g are, and does not need
+% it works. the function h remembers what f and g were, and does not need
 % to call them. This is not true for functions of the other two kinds
 
 % Here is a useful example

4_Debugger/debuggerScript.m

@@ -34,7 +34,7 @@ z = z + y;
 % select more advanced debugging tools, for example conditional breakpoints
 %
 % 1. Mark a certain line and press "Breakpoints -> Set condition"
-% 2. If we set x > 3 at line 36, the debugger will stop
+% 2. If we set x > 3 at line 39, the debugger will stop
 
 x = 4;
 z = x + 3;