% ECE 1250 Lecture 1
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% PowerPoint presentation: Sound Overview
%----------------------------------------
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% Matlab¨ is a computer language that is especially useful when processing large arrays
%  of numbers, such as images, speech, or experimental data.

% Matlab¨ has features similar to C or Java, but is distinctive for the following
%  collection of features:
% 1) Variable types do not have to be declared
% 2) Array sizes do not have to be declared and may change when necessary
% 3) Array operations are simple and well-supported

% Matlab also has some quirks such as the following:
% 1) Variables have invisible types assigned after certain (e.g., logical) operations
% 2) Array functions behave differently when operating on one-dimensional versus two-
%    dimensional arrays
% 3) Array indexing comes in many types and, though powerful, is a challenge to master
% 4) Array operations may be embedded in equations allowing massive computations, but
%    deciphering the formulas can be a challenge
% 5) Numerical values are not exact, so a result that should be zero may be shown as
%    e.g., 1e-16

% Nevertheless, Matlab¨ is the industry standard for solving numerical problems, and it
%  is a very useful language once you master it.

% Launching Matlab¨:
%  Double click on icon that is orange and blue 3D plot of surface

% Primer p. 1-3
% The Matlab¨ desktop:
% 1) Current Folder (put code here and Matlab¨ will find it)
% 2) Workspace (shows what values are stored by Matlab¨ in named variables)
% 3) Command History (previous commands, use arrow keys, too)
% 4) Command Window (type commands into the glorified graphing calculator that is Matlab¨)

% Housekeeping:
% 1) Use Preferences in MATLAB menu to set print format to compact
% 2) Change current folder to Desktop so Matlab can find files
% 3) >> pwd   % print current directory
% 4) Use Set Path under File Menu to add desired folder to where Matlab¨ looks
%    for files (remember to Save before you Close the Set Path window)
% 5) Use arrow keys to reuse previous commands (Primer p. 1-5)

% Cool things Matlab¨ can do:
>> load handel            % load a snippet of Handel's "Messiah"
>> sound(y)               % play the snippet of "Messiah" stored in variable "y"
>> plot(y(1:200))         % Shows us what the sound waveform looks like
>> y = y(2000:4048)*0.3;  % extract a portion of the sound waveform
>> sound(y)               % "ah" sound
>> plot(abs(fft(y(2000:4048))))   % Shows the frequencies in the "ah" sound
% Our goal in the labs will be to analyze sounds and then create a sound effect.

% Matlab¨ works like a calculator, but everything is typed out:
>> sin(pi)     % pi is built-in constant.
% The answer should have been zero, but Matlab¨ is numerical and rounds off.  Be careful.
sqrt(-1)         % The square root of -1 is imaginary.  Matlab¨ is okay with that.

% Some things not in the early part of the book but Very useful:
% 1) Put a semicolon ; at the end of a command to suppress printout.  Very handy for
%    huge arrays you don't want to see.
% 2) Use the >>diary on  and >>diary off  commands to create a file containing
%    a transcript of your Matlab¨ session, input and output.