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Diffstat (limited to 'matlab.html.markdown')
| -rw-r--r-- | matlab.html.markdown | 86 |
1 files changed, 79 insertions, 7 deletions
diff --git a/matlab.html.markdown b/matlab.html.markdown index 02fe5962..ddc0cb40 100644 --- a/matlab.html.markdown +++ b/matlab.html.markdown @@ -1,9 +1,11 @@ --- language: Matlab +filename: learnmatlab.mat contributors: - ["mendozao", "http://github.com/mendozao"] - ["jamesscottbrown", "http://jamesscottbrown.com"] - + - ["Colton Kohnke", "http://github.com/voltnor"] + - ["Claudson Martins", "http://github.com/claudsonm"] --- MATLAB stands for MATrix LABoratory. It is a powerful numerical computing language commonly used in engineering and mathematics. @@ -13,6 +15,7 @@ If you have any feedback please feel free to reach me at [osvaldo.t.mendoza@gmail.com](mailto:osvaldo.t.mendoza@gmail.com). ```matlab +%% Code sections start with two percent signs. Section titles go on the same line. % Comments start with a percent sign. %{ @@ -70,7 +73,7 @@ c = exp(a)*sin(pi/2) % c = 7.3891 % Calling functions can be done in either of two ways: % Standard function syntax: -load('myFile.mat', 'y') % arguments within parantheses, spererated by commas +load('myFile.mat', 'y') % arguments within parentheses, separated by commas % Command syntax: load myFile.mat y % no parentheses, and spaces instead of commas % Note the lack of quote marks in command form: inputs are always passed as @@ -121,6 +124,7 @@ 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 +x = [1:2:10] % Increment by 2, i.e. x = 1 3 5 7 9 % Matrices A = [1 2 3; 4 5 6; 7 8 9] @@ -203,6 +207,8 @@ transpose(A) % Transpose the matrix, which is the same as: A one ctranspose(A) % Hermitian transpose the matrix % (the transpose, followed by taking complex conjugate of each element) +A' % Concise version of complex transpose +A.' % Concise version of transpose (without taking complex conjugate) @@ -252,6 +258,8 @@ axis equal % Set aspect ratio so data units are the same in every direction scatter(x, y); % Scatter-plot hist(x); % Histogram +stem(x); % Plot values as stems, useful for displaying discrete data +bar(x); % Plot bar graph z = sin(x); plot3(x,y,z); % 3D line plot @@ -260,7 +268,7 @@ pcolor(A) % Heat-map of matrix: plot as grid of rectangles, coloured by value contour(A) % Contour plot of matrix mesh(A) % Plot as a mesh surface -h = figure % Create new figure object, with handle f +h = figure % Create new figure object, with handle h figure(h) % Makes the figure corresponding to handle h the current figure close(h) % close figure with handle h close all % close all open figure windows @@ -271,7 +279,7 @@ clf clear % clear current figure window, and reset most figure properties % Properties can be set and changed through a figure handle. % You can save a handle to a figure when you create it. -% The function gcf returns a handle to the current figure +% The function get returns a handle to the current figure h = plot(x, y); % you can save a handle to a figure when you create it set(h, 'Color', 'r') % 'y' yellow; 'm' magenta, 'c' cyan, 'r' red, 'g' green, 'b' blue, 'w' white, 'k' black @@ -328,7 +336,7 @@ double_input(6) % ans = 12 % anonymous function. Useful when quickly defining a function to pass to % another function (eg. plot with fplot, evaluate an indefinite integral % with quad, find roots with fzero, or find minimum with fminsearch). -% Example that returns the square of it's input, assigned to to the handle sqr: +% Example that returns the square of it's input, assigned to the handle sqr: sqr = @(x) x.^2; sqr(10) % ans = 100 doc function_handle % find out more @@ -398,7 +406,7 @@ exp(x) sqrt(x) log(x) log10(x) -abs(x) +abs(x) %If x is complex, returns magnitude min(x) max(x) ceil(x) @@ -409,6 +417,14 @@ rand % Uniformly distributed pseudorandom numbers randi % Uniformly distributed pseudorandom integers randn % Normally distributed pseudorandom numbers +%Complex math operations +abs(x) % Magnitude of complex variable x +phase(x) % Phase (or angle) of complex variable x +real(x) % Returns the real part of x (i.e returns a if x = a +jb) +imag(x) % Returns the imaginary part of x (i.e returns b if x = a+jb) +conj(x) % Returns the complex conjugate + + % Common constants pi NaN @@ -458,11 +474,67 @@ length % length of a vector sort % sort in ascending order sum % sum of elements prod % product of elements -mode % modal value +mode % modal value median % median value mean % mean value std % standard deviation perms(x) % list all permutations of elements of x +find(x) % Finds all non-zero elements of x and returns their indexes, can use comparison operators, + % i.e. find( x == 3 ) returns indexes of elements that are equal to 3 + % i.e. find( x >= 3 ) returns indexes of elements greater than or equal to 3 + + +% Classes +% Matlab can support object-oriented programming. +% Classes must be put in a file of the class name with a .m extension. +% To begin, we create a simple class to store GPS waypoints. +% Begin WaypointClass.m +classdef WaypointClass % The class name. + properties % The properties of the class behave like Structures + latitude + longitude + end + methods + % This method that has the same name of the class is the constructor. + function obj = WaypointClass(lat, lon) + obj.latitude = lat; + obj.longitude = lon; + end + + % Other functions that use the Waypoint object + function r = multiplyLatBy(obj, n) + r = n*[obj.latitude]; + end + + % If we want to add two Waypoint objects together without calling + % a special function we can overload Matlab's arithmetic like so: + function r = plus(o1,o2) + r = WaypointClass([o1.latitude] +[o2.latitude], ... + [o1.longitude]+[o2.longitude]); + end + end +end +% End WaypointClass.m + +% We can create an object of the class using the constructor +a = WaypointClass(45.0, 45.0) + +% Class properties behave exactly like Matlab Structures. +a.latitude = 70.0 +a.longitude = 25.0 + +% Methods can be called in the same way as functions +ans = multiplyLatBy(a,3) + +% The method can also be called using dot notation. In this case, the object +% does not need to be passed to the method. +ans = a.multiplyLatBy(a,1/3) + +% Matlab functions can be overloaded to handle objects. +% In the method above, we have overloaded how Matlab handles +% the addition of two Waypoint objects. +b = WaypointClass(15.0, 32.0) +c = a + b ``` |