MATLAB INTRODUCTION 

Below is a MATLAB script introducing you to 
MATLAB and giving examples of how to use the standard
atmosphere function called atmosphere4. Put the contents
of this file from below the ****** into a text file called test.m

This file and matlab function atmosphere4 cam be found http://roger.ecn.purdue.edu/%7Eandrisan/Courses/AAE490A_S2006/Buffer/


Make sure test.m and atmosphere4.m are in the MATLAB search path.

Execute the file test.m from the MATLAB command line
by typing test


******
% General Introduction to MATLAB and a
% script to use the MATLAB function called atmosphere4.

disp('Start of the script') %This line displays in the MATLAB
% Command Window the text contained within the two quote marks.
% Comment lines start with a %, like this line.
% Comment lines generate no output in the MATLAB
% Command Window (unless echo in on).
% FILE NAMES
% A MATLAB command is any command that can be executed 
% on the MATLAB Command Window.
% A MATLAB script file is a file containing MATLAB commands.
% Script files can have any name as long as it ends in .m
% Function file names (atmosphere4.m) must be the same as the 
% function name (atmosphere4) with the .m appended.
% The function name is found on the first line of the
% function file, i.e., 
% function [temp,press,rho,Hgeopvector]=atmosphere4(Hvector,GeometricFlag)
% MATLAB SEARCH PATH (the search path that MATLAB uses to find files)
% The function atmosphere4 must be in the MATLAB search path
% in order for MATLAB to find it. If it is not in the search path
% use the Set Path command in the file menu of the MATLAB Command Window.

% MATLAB COMMANDS (also MATLAB functions)
% The MATLAB function help will type the initial comment lines
% of a file until the first blank or executable line is found. 
help atmosphere4

echo on 
% Turns echo on so that all lines are printed 
% before being executed.

%type atmosphere4 % will type the entire file.
% lines like help atmosphere4 and type atmosphere4 can also
% be executed from the MATLAB command line.
echo off % Turns echo off so that all lines are not 
% printed befor being executed.

% USING FUNCTION atmosphere4 WHEN Hvector is a scalar
% Altitude data (Hvector) can be a scalar, i.e. one number.
Hvector=1000 %When a MATLAB line does not end with a ; the results 
% of the line are printed.
[rowsize,columnsize]=size(Hvector) %When a MATLAB line does not end with a ; 
%the results of the line are printed. In the case above rowsize and 
% colsize are printed.

GeometricFlag=0 % This means that the altitude data is in geopotential feet.
[temp,press,rho,Hgeopvector]=atmosphere4(Hvector,GeometricFlag)

GeometricFlag=1 % This means that the altitude data is in geometric feet.
[temp,press,rho,Hgeopvector]=atmosphere4(Hvector,GeometricFlag)

% USING FUNCTION atmosphere4 WHEN Hvector is a vector
% Altitude data (Hvector) can be a vector, i.e. an array of numbers.
Hvector=0:1000:295000; %When a MATLAB line ends with a ; the results of 
% the line is not printed.
% The above line creates a row vector called Hvector.
% it starts at value 0, ends at value 295,000 and values are incremented
% from eachother by 1000. There are to many numbers to print so
% the semicolen prevents printing of the line (296 numbers).

[rowsize,columnsize]=size(Hvector)
GeometricFlag=0 % This means that the altitude data is in geopotential feet.
[temp,press,rho,Hgeopvector]=atmosphere4(Hvector,GeometricFlag);

%PLOTTING
plot(temp,Hgeopvector)
% Try typing help plot at the MATLAB command window.
xlabel('Temperature, degR')
ylabel('Altitude, geopotential feet')
title('1976 NASA Standard Atmosphere')
text(340,55000,'Stratosphere')
text(360,36089,'Tropopause')
text(340,15000,'Troposphere (Beechcraft Baron B58 flys here)')
whos % Lists the sizes of all variables.

% TRANSPOSING VECTOR Hvector
Hvector=Hvector'; % The prime means matrix transpose (i.e. interchange 
% the rows and the columns. This will make Hvector a column vector (296x1) 
% instead of a row vector(1x296).
[rowsize,columnsize]=size(Hvector)
GeometricFlag=0 % This means that the altitude data is in geopotential feet.
[temp,press,rho,Hgeopvector]=atmosphere4(Hvector,GeometricFlag);
whos % Lists the sizes of all variables. Notice how the sizes
% of all the matrices have change from the last time we did the whos command.

% HELP COMMANDS
% If you have any questions about what a MATLAB command does
% type help command,i.e.
help text
%help help %Note that these commands have been commented out. 
% Remove the % to execute them.
%help
%help general %The many topics you can find from the help command.
%help lang
%help ops