%% 290 Class Notes January 20
% Note: Anthing after the '%' symbol is a comment and is ignored by MATALB.
% We can use MATLAB as a calculator
% Typing the following into the command window gives the expected results
2+2
2+3*2
% Note that normal rules of mathematical orders of operatation are obeyed.
% Helpful Trick: Select text in the editor and hit F9. That text is run in
% the command window.
% By default, the results are assigned to variable 'ans'. Assign them to
% a particular variable:
X=2+2
Y=2+3*2
% We can do math with variables:
X*Y
Z=X*Y
%Variable names must start with a letter and cannont have special
%characters.
LongVariableName777 = X*Y +5
% The ';' suppresses the output to the command window. The comment lets us keep track of the
% units.
c=3*10^8; % speed of light (m/s)
% We often want to work with arrays or matracies
%Create a 3x2 matrix of zeros:
A=zeros(3,2)
% 'zeros' is a function. We'll get into function in more detail in the next lectures.
% Learn about 'zeros' using the 'help' and 'doc'
help zeros
doc zeros
% Note the first index is the length of the column. The second is the
% length of a row.
%Get the top right element
A(1,2)
%Change the top right element
A(1,2)=3
% Get the top right element- note it is changed.
A(1,2)
%MATLAB default type of data is the 'double'. It uses 8 bytes (64 bits) to
%encode a floating point number. If you are interested, learn more about
%floating point numbers here: https://en.wikipedia.org/wiki/Floating_point
%If you run the following it will open a web browser:
web('https://en.wikipedia.org/wiki/Floating_point')
%we can convert between some data types
B=single(A)
% 'single' is a function that converts the input in a single floating point
% data type. Note the other data types mentioned at the end of the help:
help single
single('asdsf')
% One of the first things to do in a new language is print the 'Hello
% World message. In MATLAB, we use the 'fprintf' to print to the command
% window.
fprintf('Hello World\n')
%Try with double quotes "" instead of single ''. See what happens.
% you can run everyhing in this file at once by running the script:
% type 'Jan_20' in the command window. What will happen if I uncomment the
% next line? (Hint: cntr-c interrupts a running script or function)
% Jan_20