An Introduction to MATLAB

Transcription

1 An Introduction to MATLAB Day 1 Simon Mitchell Simon.Mitchell@ucla.edu

2 High%level%language% Programing%language%and%development%environment% Built4in%development%tools% Numerical%manipulation% Plotting%of%functions%and%data% Implement%algorithms% Create%models%and%applications% Many%built%in%functions% Interface%with%other%languages% Create%graphical%interfaces%

3 The MATLAB Environment

4 Current Folder

5 Command Window >>

6 Workspace

7 Editor

8 Command Window Basics

9 Common Arithmetic Operators + %Addition% 4 %Subtraction%% * %Multiplication% / %Division% ^ %Exponential% () %Order%operations% %

10 Semicolons in MATLAB Suppress%the%output%from%a%MATLAB%expression%

11 Comments % Suppress%the%output%from%a%MATLAB%expression%

12 Variables Variable%name%=%variable%value% % % % % % % Be%careful%of%i,j%

13 Variables 2 MATLAB%is%CASE%SENSITIVE% % % % % % %

14 Close%MATLAB% % Reopen%MATLAB%

15 Initially%Workspace% is%empty%

16 Load%your% workspace%

17 Variables to result of expression If%an%expression%is%not%stored%as%a%variable%it%will%be%stores% as% ans %

18 Multiple assignments and who

19 whos

20 format format%short %% to%get%back%to%normal%

21 Numbers are actually 1x1 Matrices

22 Operations apply to matrices

23 Operations apply to matrices

24 Put. before an operator to make it element-wise disp(variable)%displays%the% contents%of%a%variable%

25 fprintf print something to command window %s %Format%as%a%string.% %d %Format%as%an%integer.% %f %Format%as%a%floating%point%value.% %e %Format%as%a%floating%point%value%in%scientific%notation.% %g %Format%in%the%most%compact%form:%%f%or%%e.% \n %Insert%a%new%line%in%the%output%string.% \t %Insert%a%tab%in%the%output%string.%

26 Concatenating matrices

27 Concatenating matrices Why%is%this%1,1?%

28 Many Functions work on columns

29 Working with m-files 3%Ways%of%running%code% Command%Window% Scripts% Functions% m"files'

30 New Script

31 Our First Script

32 Scripts can create variables in the workspace

33 Data Types Type%declarations%are%not%necessary%in%MATLAB% MATLAB%automatically%decides%data%type%

34 Data Types single%4%single%precision%numerical%data% double%%4%double%precision%numerical%data% logical'"'logical%values%of%1%or%0,%represent%true%and%false%respectively% char''"'character%data%(strings%are%stored%as%vector%of%characters)% cell'array%4%array%of%indexed%cells,%each%capable%of%storing%an%array%of%a% different%dimension%and%data%type% structure%4%named%fields%capable%of%storing%an%array%of%a%different%dimension% and%data%type% function'handle%4%pointer%to%a%function% user'classes'"'objects%constructed%from%a%user4defined%class% Int8'uint8'int16'uint16'int32'uint32'int64'uint64' %don t%worry%about%these'

35 Data Types

36 Testing Data Types

37 Relational Operators < %Less%than% >= %Less%than%or%equal%to% > %Greater%than% >= %Greater%than%or%equal%to% == %Equal%to% ~= %Not%equal%to% % % % % Useful%for%if%statements!%

38 If Statement Never'run'

39 If else Statement

40 If elseif Statement

41 Nested if Statement

42 For loops

43 Combining What We ve Learned Write%a%script'that%takes%a%list%of%gene%names%and%gene% expression%values%and%outputs%only%those%gene%names%over%a% threshold.% % PSUEDO%CODE:% For%each%gene%in%a%list:% %if%its%expression%value%is%over%the%threshold% % %print%the%gene%name%and%the%expression%value%

44 Combining What We ve Learned PSUEDO%CODE:% For%each%gene%in%a%list:% %if%its%expression%value%is%over%the%threshold% % %print%the%gene%name%and%the%expression%value%

45 Combining What We ve Learned