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matlab [2016/02/16 09:20] (current)
jasnyder created
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 +<​p><​div align="​center"> ​                
 +<h1>A Beginning MATLAB Tutorial for&​nbsp;</​h1></​p>​ 
 +<​p><​h1>​the UC Davis Department of Mathematics</​h1></​p>​ 
 +<p>by Sarah Williams<​br>​ 
 +                <​br>​ 
 +                updated 9/​15/​2003<​br>​ 
 +                </​div></​p>​ 
 +<​p><​hr> ​ <font size="​+1">​Introduction and Overview</​font><​br></​p>​ 
 +            <​li>​What is MATLAB?</​li>​ 
 +            <​li>​Why use MATLAB? Why not?</​li>​ 
 +              <!-- <​li>​What to expect from this workshop and beyond </li> --></​p>​ 
 +           <​font size="​+1">​Command-Line MATLAB</​font><​br></​p>​ 
 +           <​li>​Launch MATLAB</​li>​ 
 +           <​li>​Generate matrices</​li>​ 
 +           <​li>​Implement functions</​li>​ 
 +           <​li>​Write a small program that generates a plot</​li></​p>​ 
 +           <​font size="​+1">​M-File MATLAB</​font><​br></​p>​ 
 +           <​li>​Directory Structure (where will you save your file?​)</​li>​ 
 +           <​li>​Put your small program into an m-file, and run it</​li>​ 
 +           <​li>​Scripts vs. Functions: write a function m-file</​li>​ 
 +  <​li>​Get your Scripts and Functions Talking</​li>​ 
 +  <​li>​Add More Features and Get More Help<​br><​p> ​ </​li></​p>​ 
 +           <​font size="​+1"></​font>​ 
 +<​p><​hr width="​100%"​ size="​2"><​font size="​+1">​Introduction and Overview</​font><​br>​ 
 +          <​br></​p>​ 
 +<​p>​Please note that MatLAB can be accessed both on the department computers and from home via SSH.  From home, one can even combine SSH with X Windows to use the graphical version of MatLAB.</​p>​ 
 +<​h2><​h3><​a name="​IntroA"></​a>​What is MATLAB?</​h3></​h2>​ 
 +<​p> ​         MATLAB is both a programming language and a software package. &​nbsp;"​MATLAB"​ 
 +     ​stands for "​Matrix Laboratory."​ &​nbsp;​Accordingly,​ many features exploit  
 +    matrices, and assume you are working with matrices. &​nbsp;​MATLAB  
 +generally solves  
 +  problems numerically,​ not symbolically (compared to Mathematica).<​br>​ 
 +          <​br></​p>​ 
 +<​p><​h3><​a name="​IntroB"></​a>​Why use MATLAB? Why not?</​h3>​ 
 +          Pros:<​br></​p>​ 
 +            <​li>​It'​s easy to start using MATLAB, with or without prior programming 
 +     ​experience.</​li><​p> ​           <​li>​MATLAB has a lot of built-in mathematical knowledge; e.g.  
 +MATLAB ​   has  a function to find the 1-, 2-, or max-norm of a vector -- you 
 +don'​t ​  have to program this yourself.<​br>​ 
 +            </​li>​ 
 +            <​li>​MATLAB has a lot of very powerful "​toolboxes"​ to work in 
 +specific ​    areas of math (optimization,​ wavelets, etc.)</​li>​ 
 +            <​li>​It'​s easy to produce nice graphs.</​li></​p>​ 
 +  <​li>​MATLAB has a lot of "​overhead,"​ like graphics and notation that make 
 +it easy to use. &​nbsp;​This can slow it down compared to more bare-bones programming 
 +languages (like C, FORTRAN). MATLAB may be too slow to solve some  
 +large problems.</​li><​p> ​ <​li>​MATLAB is not free - although we have good access at school (and you 
 +can run the school'​s version remotely), if you happen to want your own private 
 +copy, it costs $100 for students, and more for each toolbox.</​li>​ 
 +<​p><​!-- ​                                  
 +<​h3>​What to expect from this workshop and beyond</​h3>​ 
 +          After this workshop, you will be able to:<​br></​p>​ 
 +            <​li>​complete a practice MATLAB homework assignment (based  
 +on mat228a)</​li>​ 
 +            <​li>​write a program, save it, run it, edit it, and run it again</​li><​p> ​           <​li>​save subroutines in different files and call them from the 
 + ​main ​  ​program<​br>​ 
 +            </​li>​ 
 +            <​li>​make simple graphs</​li>​ 
 +            <​li>​look for more help in the MATLAB documentation</​li></​p>​ 
 +          After working with MATLAB this quarter, you can expect to:<​br></​p>​ 
 +            <​li>​be familiar with a lot of useful functions built into MATLAB</​li>​ 
 +            <​li>​recognize common error messages and how to fix them</​li>​ 
 +            <​li>​make more complex graphs<​br>​ 
 +            </​li></​p>​ 
 +<​p><​hr width="​100%"​ size="​2"> ​          
 +           <​font size="​+1">​Command-Line MATLAB</​font><​br></​p>​ 
 +<​p><​h3>​Launch MATLAB</​h3></​p>​ 
 +            <​li>​Click (once) on the MATLAB icon. (Enter your password  
 + ​when ​  ​prompted.)</​li>​ 
 +<​li>​OR from the terminal window type "ssh sine" (enter) and then  
 +<​p><​h3>​Generate matrices</​h3></​p>​ 
 +            <​li>​Find the panel called the Command Window. &​nbsp;​This is where  
 +  we  will  be working.</​li>​ 
 +            <​li>​Type the following commands:</​li><​p> ​ <​ul>​ 
 +             <​li>​In what follows, the&​nbsp;<​font 
 + ​face="​Courier New, Courier">&​gt;&​gt;</​font> ​   symbol is meant to represent  
 + the MATLAB prompt (i.e., don't type this yourself).</​li><​p> ​            <​li>​Hit the return key at the end of each line; observe the 
 +result ​   and  try to understand the cause-and-effect of your commands.  
 +   </​li></​p>​ 
 +<​p> ​ </​ul>​ 
 +           <​br>​ 
 +                <font face="​Courier New, Courier">&​gt;&​gt;​ A = [1 2 3; 4 5  6]<​br>​ 
 +          &​gt;&​gt;​ B = [7; 8; 9] <​br>​ 
 +          &​gt;&​gt;​ C = A*B<​br><​p> ​            <​br>​ 
 +             </​font> ​   <​li>​Now try a slightly different version of the same 
 +  thing:<​br>​ 
 +             <​br>​ 
 +              <font face="​Courier New, Courier">&​gt;&​gt;​ clear<​br>​ 
 +                                            &​gt;&​gt;​ A = [1 2 3; 4 5 6];</​font>​  
 +   ​(note ​ the semicolon at the end)<​br><​p> ​             <font face="​Courier New, Courier">&​gt;&​gt;​ B = [7 8 9]'; </​font>​ 
 +   ​(note ​  the apostrophe)<​br>​ 
 +              <font face="​Courier New, Courier">&​gt;&​gt;​ C = A*B; <​br>​ 
 +                                            &​gt;&​gt;​ C<​br>​ 
 +                                            &​gt;&​gt;​ C'<​br></​p>​ 
 +<​p> ​            <​br>​ 
 +             </​font></​li>​ 
 +            <​li>​Accessing matrix entries (vector components):<​br>​ 
 +             <​br>​ 
 +              <font face="​Courier New, Courier"> ​                        
 +         &​gt;&​gt;</​font>&​nbsp;​A<​br>​ 
 +             <​font face="​Courier New, Courier"> ​                         
 +        &​gt;&​gt;</​font>&​nbsp;​A(1,​1)<​br><​p> ​             <font face="​Courier New, Courier"> ​                        
 +         &​gt;&​gt;</​font>&​nbsp;​A(1,​2)<​br>​ 
 +              <font face="​Courier New, Courier"> ​                        
 +         &​gt;&​gt;</​font>&​nbsp;​A(2,​1)<​br>​ 
 +              <font face="​Courier New, Courier"> ​                        
 +             </​font><​font face="​Courier New, Courier"> ​                  
 +               &​gt;&​gt;</​font>&​nbsp;​B<​br>​ 
 +             <​font face="​Courier New, Courier">&​gt;&​gt;</​font>&​nbsp;​B(1,​1)<​br>​ 
 +              <font face="​Courier New, Courier"> ​                        
 +         &​gt;&​gt;</​font>&​nbsp;​B(1)<​br></​p>​ 
 +<​p> ​             <font face="​Courier New, Courier"> ​                        
 +         &​gt;&​gt;</​font>&​nbsp;​B(3)<​br>​ 
 +             <​br>​ 
 +           </​li>​ 
 +            <li>A very handy way of making uniformly spaced "​grids"​ in MATLAB:<​br>​ 
 +            <​br>​ 
 +                <font face="​Courier New, Courier">&​gt;&​gt;​ clear<​br></​p>​ 
 +<​p> ​         &​gt;&​gt;​ X = 1:5 <​br>​ 
 +          &​gt;&​gt;​ Y = 3:0.3:5 <​br>​ 
 +                                                  &​gt;&​gt;​ Z = [0:​(pi/​4):​(2*pi)]'<​br>​ 
 +            <​br>​ 
 +            </​font></​li>​ 
 +            <​li>​To ​ review:</​li></​p>​ 
 +<​p> ​ <​ul>​ 
 +              <​li>​Put square brackets [] around matrices.</​li>​ 
 +              <​li>​You will get a single row if you just type numbers in the  
 + ​brackets. ​   &​nbsp;​To go to the next row, type a semicolon.</​li>​ 
 +              <​li>​Use * for matrix multiplication (works for regular multiplication,​ 
 +     ​too).</​li>​ 
 +              <​li>​MATLAB repeats what you just typed. &​nbsp;​To suppress this,  
 +  put   a semicolon ; at the end of the line.</​li>​ 
 +              <​li>​To see the value of a matrix (or other variable) you've  
 +entered, ​    just type its name and hit return.<​br><​p> ​             </​li>​ 
 +              <​li>​An apostrophe gives you the transpose (the complex conjugate 
 +   ​transpose, ​  in fact) of the matrix.<​br>​ 
 +              </​li>​ 
 +              <​li>​To refer to the component of matrix A in the mth row down  
 + ​and ​  ​nth ​ column over, type A(m,n). &​nbsp;​If A is a row or column vector,  
 + ​you ​ can just  type A(j) to see the jth component. &​nbsp;<​br>​ 
 +              </​li>​ 
 +              <​li>​The colon : notation gives you uniformly spaced grids (row 
 +  or  column ​ vectors). &​nbsp;​The first number is the left endpoint of the 
 + ​grid. ​ &​nbsp;​If ​ you include a middle number, it's the grid spacing (delta 
 + x); if  you don'​t ​ state a value here, MATLAB assumes you want a value of 
 + 1. &​nbsp;​The ​ last number is the maximum right endpoint of the grid.</​li></​p>​ 
 +<​p> ​             <​li>​The command "​clear"​ erases all the variable values you've  
 + ​assigned ​   so you can start fresh. &​nbsp;​Use this often -- MATLAB has a  
 +bad habit of   ​leaving remnants of old variables lying around unless you explicitly 
 +clear   them out.&​nbsp;​ &​nbsp;<​br>​ 
 +              </​li></​p>​ 
 +<​p> ​ </​ul></​p>​ 
 +<​p><​h3>​Implement functions</​h3></​p>​ 
 +            <​li>​Type the following commands:<​br><​p> ​           <​br>​ 
 +                <font face="​Courier New, Courier">&​gt;&​gt;​ clear <​br>​ 
 +                                                  &​gt;&​gt;​ c = -pi/2; <​br>​ 
 +                                                  &​gt;&​gt;​ X = [0:​0.1:​1]';​ 
 +     <​br>​ 
 +           <​br>​ 
 +                                                  &​gt;&​gt;​ sin(c)<​br></​p>​ 
 +<​p> ​       </​font><​br>​ 
 +                                                    Now, type the "​up"​ arrow.  
 +   ​MATLAB ​  will display the last thing you typed. ​                       
 +             (Type "​up"​ again and you can move backwards through your command 
 +   ​history.) ​                                           Use the arrow keys 
 + ​to ​ edit the last  line to read:<​br>​ 
 +           <​br>​ 
 +               <​font face="​Courier New, Courier">​ &​gt;&​gt;​ sin(X) <​br>​ 
 +              <​br>​ 
 +                                                  &​gt;&​gt;​ sqrt(c) </​font></​p>​ 
 +<p> (Note    the  imaginary value.)<​br>​ 
 +               <​font face="​Courier New, Courier">​ &​gt;&​gt;​ sqrt(abs(c))<​br>​ 
 +              <​br>​ 
 +                                                  &​gt;&​gt;​ Y = exp(X)<​br>​ 
 +                                                  &​gt;&​gt;​ Z = log(Y)<​br><​p> ​                                                 </​font></​li></​p>​ 
 +<​p><​h3>​Write a small program that generates a plot</​h3></​p>​ 
 +            <​li>​Type the following commands to plot a semi-circle:<​br>​ 
 +       ​(Note:​ <font face="​Courier New,​Courier">​.^</​font>​ gives the component-wise 
 +     ​square,​ i.e., it raises each entry of X to the power of 2.) <​br><​p> ​               <font face="​Courier New, Courier"><​br>​ 
 +       &​gt;&​gt;​ clear <​br>​ 
 +                                                  &​gt;&​gt;​ X = -2:0.1:2; 
 +    <​br>​ 
 +                                                  &​gt;&​gt;​ Y = sqrt(4-(X.^2));</​font><​br>​ 
 +                <font face="​Courier New, Courier">&​gt;&​gt;​ plot(X,Y) <​br><​p> ​                                 </​font></​li></​p>​ 
 +<​p><​hr width="​100%"​ size="​2"><​br>​ 
 +          <font size="​+1">​M-File MATLAB</​font><​br>​ 
 +          Typing commands directly to MATLAB is well and good, and you will  
 + ​want ​  ​to ​ experiment at the command line frequently. &​nbsp;​However,​ for  
 +homework ​  ​assignments ​ and other distinct problems, you will want to keep  
 +your program ​  in a file,  so that you can edit it and run it again. &​nbsp;​You  
 +will also   want to make  files that call each other -- for example, you could 
 +have a  plotting routine ​ that uses the format you like, and each of your 
 +programs ​  could call this routine when it comes time to make a graph.<​br></​p>​ 
 +<​h2><​h3>​Directory Structure (where will you save your file?​)</​h3></​h2>​ 
 +<​p> ​         Now is the time when we talk about Linux. &​nbsp;​If you already 
 +know   ​which ​  ​directory you will save your program files in, skip to the 
 +next section.<​br></​p>​ 
 +            <​li>​Put MATLAB aside for a moment. &​nbsp;​(Minimize the window  
 +if  you   ​like.)</​li>​ 
 +            <​li>​Click on the "​Localhost"​ icon to get a new terminal window.</​li>​ 
 +            <​li>​Initially,​ you are "​sitting"​ at your "​home"​ directory.</​li>​ 
 +            <​li>​Type ls to list the subdirectories.</​li><​p> ​           <​li>​Do you have a subdirectory where you put your coursework?  
 +&​nbsp;​Would ​    you like one?</​li>​ 
 +            <​li>​To create a subdirectory called Courses, type mkdir Courses  
 + ​(you ​  ​can ​ change Courses to any other name you prefer)</​li>​ 
 +            <​li>​Now type cd Courses (cd means change directory)</​li>​ 
 +            <​li>​Now you are sitting at your Courses directory.</​li>​ 
 +            <​li>​Type ls to list what's here. &​nbsp;​Nothing,​ right? &​nbsp;​Let'​s 
 +   ​put ​  ​something here.</​li></​p>​ 
 +<​p> ​           <​li>​Type mkdir Math228a to make a directory for numerics.</​li>​ 
 +            <​li>​Now type ls. &​nbsp;​Can you see your new folder? &​nbsp;​This 
 + ​is ​ a  good  place to store your MATLAB programs.</​li>​ 
 +            <​li>​You can exit the terminal window now (type exit) and bring 
 + ​your ​  ​MATLAB ​ window back.<​br>​ 
 +            </​li></​p>​ 
 +<​p><​h3>​Put your small program into an m-file, and run it</​h3></​p>​ 
 +            <​li>​At the top left of the MATLAB window, there is an icon that  
 + ​looks ​   like a "new document"​ button. &​nbsp;​Click (once) on this.</​li>​ 
 +                 <​li>​A blank editor window will open. &​nbsp;​This is where  
 +you   ​type ​ your  program. &​nbsp;​Type:<​br>​ 
 +      (Note: in my experience, trying to copy and paste text into the MATLAB 
 +  editor ​ crashes the whole thing. &​nbsp;​You can try it, but you'll learn 
 +more  if you  type the text yourself anyway.)<​font 
 + ​face="​Courier New, Courier"> ​     <​br>​ 
 +              <​br><​p> ​         % My Name<​br>​ 
 +              </​font><​font face="​Courier New, Courier">​% The Date<​br>​ 
 +          % The purpose of this program is to plot a semi-circle on [-2,​2].<​br>​ 
 +           </​font><​font face="​Courier New, Courier"> ​  ​X&​nbsp;​= -2:​0.1:​2;<​br>​ 
 +          Y = sqrt(4-(X.^2));<​br></​p>​ 
 +<​p> ​         plot(X,​Y)</​font><​font face="​Courier New, Courier"><​br>​ 
 +              <​br>​ 
 +              </​font></​li>​ 
 +            <​li>​The percent signs % indicate comments. &​nbsp;​You can put 
 +these    anywhere ​  in a program, to explain your code. &​nbsp;​Use comments 
 +as often    as possible; ​  ​otherwise,​ you will not remember why you did what 
 +you did.<​br>​ 
 +              </​li>​ 
 +            <​li>​Click on the File menu, and choose "Save As."</​li></​p>​ 
 +<​p> ​ <​ul>​ 
 +           <​li>​You want the top field to contain the right directory (the  
 +one   ​you ​  ​created in the last step). &​nbsp;</​li>​ 
 +           <​li>​In the bottom field, type the name of the program. &​nbsp;​Call 
 +  it   ​circle1.m</​li></​p>​ 
 +<​p> ​ </​ul>​ 
 +         <​li>​If your semi-circle figure is still open from before, close 
 +         <​li>​Click on the command window.</​li><​p> ​        <​li>​Take a look at the top of the window. &​nbsp;​There is a field  
 +labeled ​    "​Current Directory."​ &​nbsp;​Is it looking in the right place for  
 +your program?</​li></​p>​ 
 +<​p> ​ <​ul>​ 
 +                                   <​li>​If not, you can type "​cd"​ and "​ls'​  
 +in  MATLAB ​ just like you can in  the terminal window. &​nbsp;​You might need 
 + ​to ​ type something ​ like<​br>​ 
 +             <​font face="​Courier New, Courier, monospace">&​gt;&​gt;​ cd Courses/​Math228a</​font></​li></​p>​ 
 +<​h2> ​ </​ul></​h2>​ 
 +<​p> ​      <​li> ​                                                       type ls 
 + ​to ​ see  if your program is there. To run your program, type its name, e.g.<​br>​ 
 +          <font face="​Courier New, Courier, monospace">&​gt;&​gt;​circle1</​font><​br>​ 
 +            </​li></​p>​ 
 +<​p><​h3>​Scripts vs. Functions: write a function m-file</​h3></​p>​ 
 +            <​li>​The program you just wrote, circle.m, is called a "​script"​ 
 + ​- ​ it  runs straight from beginning to end, like a script to a play.</​li><​p> ​       <​li>​In ​  ​MATLAB,​ you can also write a program that is a function.</​li></​p>​ 
 +<​p> ​ <​ul>​ 
 +              <li>A function usually takes input and returns output.</​li></​p>​ 
 +<​p> ​ </​ul></​p>​ 
 +<​p> ​ <​ul>​ 
 +              <li>A function file must start with a "​function declaration."​  
 + &​nbsp;​We ​ will see an example below.</​li></​p>​ 
 +<​h2> ​ </​ul></​h2>​ 
 +<​p> ​           <​li>​Open a blank program file. &​nbsp;​Type:<​br>​ 
 +              <​br>​ 
 +               <​font face="​Courier New, Courier">​% My Name<​br>​ 
 +            % The Date<​br>​ 
 +            % The purpose of this program is to plot a semi-circle of a<​br>​ 
 +            % given radius.<​br><​p> ​             <​br>​ 
 +            function Y = circle2(radius)<​br>​ 
 +            X = -radius:​0.1:​radius;<​br>​ 
 +            Y = sqrt(radius^2-(X.^2));<​br>​ 
 +            plot(X,​Y)<​br>​ 
 +              <​br>​ 
 +              </​font></​li></​p>​ 
 +<​p> ​           <​li>​The line&​nbsp;<​font face="​Courier New, Courier">​function 
 +Y  =  circle2(radius)</​font> ​   is the function declaration. &​nbsp;​Note:</​li></​p>​ 
 +<​p> ​ <​ul>​ 
 +              <​li>​The word "​function"​ must be the first (non-comment) word 
 + ​of ​ the   ​program.</​li>​ 
 +              <​li>"​Y"​ is the value that this function returns, or calculates,  
 +  a.k.a. the output.</​li>​ 
 +          <​li>"​radius"​ is the name of the variable taken as input.</​li><​p> ​         <​li>"​circle2"​ should be both the name of the function and the name 
 +  that  you use to save the file.</​li></​p>​ 
 +<​p> ​ </​ul>​ 
 +        <​li>​To run your program for different radii, type:<​br>​ 
 +          <font face="​Courier New, Courier, monospace"><​br>​ 
 +      &​gt;&​gt;​circle2(2)<​br>​ 
 +          </​font><​font face="​Courier New, Courier, monospace">&​gt;&​gt;​circle2(4)</​font>;<​br><​p> ​         <font face="​Courier New, Courier, monospace">&​gt;&​gt;​circle2(1);<​br>​ 
 +          <​br>​ 
 +          </​font></​li>​ 
 +        <​li>​Note that the figure is replaced each time you call the function,  
 +  and that MATLAB automatically chooses the size of the x- and y-axes.<​br>​ 
 +          </​li></​p>​ 
 +          <​br></​p>​ 
 +<​p><​h3>​Get your scripts and functions talking</​h3></​p>​ 
 +       <​li>​Open a blank program file. &​nbsp;​Type:<​br>​ 
 +         <​br>​ 
 +         <​font face="​Courier New, Courier">​% My Name<​br>​ 
 +            % The Date<​br>​ 
 +            % The purpose of this program is to plot semi-circles ​     <​br><​p> ​    % with radius = 1,2,3, and 4.<​br>​ 
 +         <​br>​ 
 +     for j = 1:​4<​br>​ 
 +     &​nbsp;​ &nbsp; circle2(j);<​br>​ 
 +     ​end<​br>​ 
 +        <​br><​p> ​       </​font></​li>​ 
 +      <​li>​Save the file (in the same directory as circle2.m) as makecircles.m</​li>​ 
 +    <​li>​makecircles.m is a script. &​nbsp;​It is "​calling"​ circle2.m, which  
 +is a function. &​nbsp;​They'​re talking to each other. &​nbsp;​(Who is saying what?​)<​br>​ 
 +    </​li>​ 
 +     <​li>​Close any plots that are still open.</​li>​ 
 +     <​li>​To run the program, type:<​br></​p>​ 
 +<​p> ​      <​br>​ 
 +       <​font face="​Courier New, Courier, monospace">&​gt;&​gt;​ clear<​br>​ 
 +   &​gt;&​gt;​ makecircles</​font><​br>​ 
 +       <​br>​ 
 +     </​li>​ 
 +     <​li>​Did you get what you expected? &​nbsp;​To make the program produce  
 +4  different plots without overwriting,​ we need to make a small edit:</​li></​p>​ 
 +<​p> ​ <​ul>​ 
 +       <​li>​open your circle2.m file (probably it is still open in the editor  
 + ​window and you just need to click on its tab at the bottom of the window)</​li>​ 
 +       <​li>​insert a line that says "<​font 
 + ​face="​Courier New, Courier, monospace">​figure</​font>"​ right above <font 
 + ​face="​Courier New, Courier, monospace">​plot(X,​Y)</​font>​. &​nbsp;​This means  
 + "​create a new figure (don't overwrite the last one)."</​li>​ 
 +       <​li>​Now your program should read as follows:<​br>​ 
 +         <​br><​p> ​        <​font face="​Courier New, Courier">​% My Name<​br>​ 
 +            % The Date<​br>​ 
 +            % The purpose of this program is to plot a semi-circle of a<​br>​ 
 +            % given radius.<​br>​ 
 +              <​br>​ 
 +            function Y = circle2(radius)<​br><​p> ​           X = -radius:​0.1:​radius;<​br>​ 
 +            Y = sqrt(radius^2-(X.^2));<​br>​ 
 +         <​font face="​Courier New, Courier, monospace">​figure</​font><​br>​ 
 +            plot(X,​Y)</​font><​br>​ 
 +         <​br>​ 
 +       </​li></​p>​ 
 +<​h2> ​ </​ul></​h2>​ 
 +<​p> ​    <​li>​Save circle2.m, close any figures that are open, and run makecircles  
 +      <​br>​ 
 +    </​li>​ 
 +    <li>A different option: make the program produce one plot showing all  
 +4 circles</​li></​p>​ 
 +<​p> ​ <​ul>​ 
 +      <​li>​open your circle2.m file</​li>​ 
 +      <​li>"​comment out" the "<​font 
 + ​face="​Courier New, Courier, monospace">​figure</​font>" ​ &​nbsp;​line. &​nbsp;​That 
 +is, put a <font face="​Courier New, Courier, monospace">​%</​font>​ in front 
 +of it.</​li><​p> ​   <​ul>​ 
 +        <​li>​MATLAB will not read your comments</​li>​ 
 +        <​li>"​commenting out" can be better than deleting, because you can  
 +easily go back if you change your mind. (by erasing the <font 
 + ​face="​Courier New, Courier, monospace">​%</​font>​ mark)</​li></​p>​ 
 +<​p> ​   </​ul>​ 
 +      <​li>​above <font face="​Courier New, Courier, monospace">​plot(X,​Y)</​font>,​ 
 + add a line that says "<​font face="​Courier New, Courier, monospace">​hold 
 +on</​font>​."</​li><​p> ​     <​li>​Now your program should read as follows:<​br>​ 
 +        <​br>​ 
 +        <font face="​Courier New, Courier">​% My Name<​br>​ 
 +            % The Date<​br>​ 
 +            % The purpose of this program is to plot a semi-circle of a<​br>​ 
 +            % given radius.<​br><​p> ​             <​br>​ 
 +            function Y = circle2(radius)<​br>​ 
 +            X = -radius:​0.1:​radius;<​br>​ 
 +            Y = sqrt(radius^2-(X.^2));<​br>​ 
 +         <​font face="​Courier New, Courier, monospace">​%figure<​br>​ 
 +        </​font>​hold on<​br></​p>​ 
 +<​p> ​           plot(X,​Y)</​font><​br>​ 
 +      <​br>​ 
 +    </​li>​ 
 +  </​ul>​ 
 +  <​li>​Save cirlce2.m, close any figures that are open, and run makecircles 
 +  <​li>​To save your plot:</​li>​ 
 +  <​ul></​p>​ 
 +<​p> ​   <​li>​At the top of the plot window, click on File</​li>​ 
 +    <​li>​click on Export</​li>​ 
 +    <​li>​Verify that it's going in the right directory, give it a name in 
 +place of where it now says *, (try cplot1), and choose a format (eps or color 
 +eps is good)<​br>​ 
 +      <​br>​ 
 +    </​li>​ 
 +  </​ul>​ 
 +  <​ul></​p>​ 
 +<​p> ​ </​ul></​p>​ 
 +<​p><​h3>​Add More Features and Get More Help<​br>​ 
 +  <​li>​Plots should have titles. &​nbsp;​How do you add a title?</​li>​ 
 +  <​ul>​ 
 +    <​li>​In the MATLAB window, click on the Help menu item. &​nbsp;​From the 
 +list that drops down, choose "​MATLAB Help."</​li><​p> ​   <​li>​You'​ll get a new window full of help. &​nbsp;</​li>​ 
 +    <​li>​In the left-hand pane, there are 4 tabs: Contents, Index, Search, 
 +and Favorites. &​nbsp;​Click on Search.</​li>​ 
 +    <​li>​In the blank box, type "​title"​ (and hit return)</​li>​ 
 +    <​li>​double-click on the first "​hit"​ -- the one that simply says "​title."</​li>​ 
 +    <​li>​Read the help in the right-hand pane, and see if you can add a line 
 +to your program so that your plot will have a title.<​br>​ 
 +      <​br></​p>​ 
 +<​p> ​   </​li>​ 
 +  </​ul>​ 
 +  <​li>​Maybe you'd rather change the x-axis of your plot, so that it shows 
 +  <​ul>​ 
 +    <​li>​Back in the help window, search for "​axis"</​li>​ 
 +    <​li>​double-click on the "​hit"​ that looks the best</​li>​ 
 +    <​li>​go to it!<​br></​p>​ 
 +<​p> ​   </​li>​ 
 +  </​ul>​ 
matlab.txt · Last modified: 2016/02/16 09:20 by jasnyder