tutor2.m

很多matlab的源代码

% ADSP Toolbox: Version 2.0 
% For use with "Analog and Digital Signal Processing", 2nd Ed.
% Published by PWS Publishing Co.
%
% Ashok Ambardar, EE Dept. MTU, Houghton, MI 49931, USA
% http://www.ee.mtu/faculty/akambard.html
% e-mail: [e-mail]
% Copyright (c) 1998

clc,echo on
%			EXPRESSIONS AND STRING FUNCTIONS

%MATLAB has the capability of evaluating expressions if they are first defined
%as string functions.

%To define y=4*x+3 as a string expression we use single quotes:
y='4*x+3'

%Note how MATLAB answers with the actual expression 4x+3 .

%Note that, y='4x+3' cannot be evaluated until x is assigned some value(s).

pause  %Strike a key to continue

%With y='4x+3', here is how we evaluate x at x=0, 2, 3 and 5. We type
x=[0 2 3 5]  %Values of x in an array
z=eval(y)    %z yields y evaluated for various x

%Values of z can now be used for any purpose.

pause  %Strike a key to continue
clc
%				FUNCTION FILES
%MATLAB allows us to use our own functions by defining them in an m-file.
%Such an m-file is called a FUNCTION M-FILE.

%As an example sinc(x) is defined as sin(pi*x)/(pi*x) in the m-file sinc.m
%To see its contents, we issue the command type sinc (without the extension).

pause %Strike a key to see the contents of sinc.m

echo off
disp('function y = sinc(x)')
disp('% SINC Sinc Function.')
disp('%')
disp('%      Y=SINC(X) generates sin(pi*x)/(pi*x)')
disp(' ')
disp('x=pi*x;i=find(x==0);[m,n]=size(i);x(i)=ones(m,n);')
disp('y=sin(x)./x;y(i)=ones(m,n);')
echo on


%EXPLANATION: The first line is the function definition and arguments
%Lines after % are comments that appear when we type HELP SINC

%NOTES: The actual function evaluation follows the help section 
%The internal variables of the m-file are not stored in the workplace
%Only the final resut is assigned to the output!!

%Even though the output and input arguments are y and x, we can assign
%any variables of our choice to evaluate the function.

pause  %Strike a key to continue

%For example, with t=-2:0.5:1; we can evaluate z=sinc(t+1) by typing
t=-2:0.5:1
z=sinc(t+2)

%Function files allow us to extend MATLAB. Many of the m-files that come
%supplied with the text are function files to perform various tasks.

pause  %Strike a key to continue
clc
%				FUNCTION EVALUATION

%Functions in a function m-file can be evaluated using the command feval
%This facility is often used within other function m-files.

%Thus if sinc.m is a function m-file for computing sinc(x),
%we can evaluate it for f=0:.25:1 by typing
f=0:.25:1
p=feval('sinc',f)

%Notice how sinc is entered as a string function.
%It is followed by all the needed input arguments.

pause  %Strike a key to continue
clc
%				SCRIPT M-FILES

%Script m-files are simply a series of MATLAB commands stored in an m-file
%They are different from function m-files.

%Typing the filename simply executes the commands in succession.
%All the variables remain in the workplace.

%An example of a script m-file is converr

pause  %Strike a key to see its contents
type converr

pause  %Strike a key to continue

%Script files may contain any commands and call any functions.

%To see what converr does (while suppressing the output), we simply type
%converr

pause  %Strike a key to continue
echo off,converr;echo on

%Function files and script files are ASCII files and may be created using
%any text editor or word processor capable of storing ASCII text.

pause  %Strike a key to continue
clc
%				DIARY

%The commands executed in a MATLAB session can be stored in a file
%To store subsequent commands in the file junk.m, we enter the command
diary junk.m
x=0:.2:1

%All MATLAB commands and text screen displays are stored until
%we issue the command
diary off

pause  %Strike a key to continue

%Here are what is stored in the diary


type junk.m

pause  %Strike a key to continue

%This file may be used as a script file to run the commands but it must be
%first cleaned up using a text editor by retaining only the commands
%and deleting all prompt signs and screen output.

%To append more commands, enter diary on
%To create a new diary say junk2.m, enter diary junk2.m

%NOTE: MAKE SURE YOU DELETE THIS FILE BY TYPING THE COMMAND APPROPRIATE
%FOR YOUR OPERATING SYSTEM (from within MATLAB or otherwise)

pause  %Strike a key to END THIS PORTION
clc,echo off
clear