ShockProp(xi,prop1,prop2)

function ShockProp(xi,prop1,prop2)
%	======================================================
%
% The program interpolates Normal Shock Properties from a given table of
% properties.  
% Table found at: http://utwired.engr.utexas.edu/che354/normal_shock.pdf
% Modified to match values from textbook Fundamentals of Aerodynamics by
% John D. Anderson (2005)
%
% Input parameters explained:
%   xi: The known parameter, related to property prop1.  Can be a single
%       integer or a 1-dimensional matrix
%   prop1: The known property, related to xi
%   prop2: The unknown quantity searched for, related to output desired
%
% Properties valid for prop1 and prop2
% 	prop*      | Book Name      | Description
%	-------------------------------------------------------------
%   M          | M1             | Incoming Mach
%   sprat      | p2/p1          | Static Pressure Ratio
%   denrat     | ?2/?1          | Density Ratio
%   Trat       | T2/T1          | Temperature Ratio
%   tprat      | p02/p01        | Total Pressure Ratio
%   tsprat     | p02/p1         | Total to Static Pressure Ratio
%   M2         | M2             | Outgoing Mach
%
%   
% Examples of the program in use:
%
% Written by Jared Miller for Professor Kevin Cole
% Last modified: August 14, 2009
%
%	======================================================

%Loads the shock table
    load shockdata.mat data


%Check to see which properties are being asked for and then picks the right
%range for x and y.
if strcmp(prop1,'M')==1
    x=data(:,1);
elseif strcmp(prop1,'M2')==1
    x=data(:,2);
elseif strcmp(prop1,'sprat')==1
    x=data(:,3);
elseif strcmp(prop1,'denrat')==1
    x=data(:,4);
elseif strcmp(prop1,'Trat')==1
    x=data(:,5);
elseif strcmp(prop1,'tprat')==1
    x=data(:,6);   
elseif strcmp(prop1,'tsprat')==1
    x=data(:,7);     
else
    error('Prop1 not specified correctly.  Valid entries: M,M2,sprat,denrat,Trat,tprat,tsprat (case sensitive)')
end
if strcmp(prop2,'M')==1
    y=data(:,1);
elseif strcmp(prop2,'M2')==1
    y=data(:,2);
elseif strcmp(prop2,'sprat')==1
    y=data(:,3);
elseif strcmp(prop2,'denrat')==1
    y=data(:,4);
elseif strcmp(prop2,'Trat')==1
    y=data(:,5);
elseif strcmp(prop2,'tprat')==1
    y=data(:,6);   
elseif strcmp(prop2,'tsprat')==1
    y=data(:,7);    
else
    error('Prop2 not specified correctly.  Valid entries: M,M2,sprat,denrat,Trat,tprat,tsprat (case sensitive)') 
end
    
%checks to see that xi lies within the valid range of x
xmax=max(x);
xmin=min(x);
ximax=max(xi);
ximin=min(xi);
if ximax>xmax
    str = num2str(xmax);
    str2 = num2str(ximax);
    error([prop1,' value (',str2,') is too large.  Maximum ',prop1,' value is ',str])       
elseif ximin<xmin
    str = num2str(xmin);   
    str2 = num2str(ximin);
    error([prop1,' value (',str2,') is too small.  Minimum ',prop1,' value is ',str])   
end    

%Interpolates using built-in MATALB interpolate function, interp1
IdealAir=interp1(x,y,xi);

%displays on screen (optional step)
    disp([prop2,' = ',num2str(IdealAir)]);