This is not my code, it is used from an answered question on here. How could I functionalize it?

[num,txt,raw] = xlsread('p.xls') ;

P = num(:,1) ;

RV = num(:,2) ;

D = num(:,3) ;

% Pick a pressure value

Pi = input('Input pressure value:','s') ;

Pi = str2double(Pi) ;

tol = 10^-3 ;

idx = abs(P-Pi)<=tol ; % check is Pi present in data

if any(idx)

fprintf('%f is present in the data\n',Pi) ;

Pi = P(idx) ;

RVi = RV(idx) ;

Di = D(idx) ;

else

fprintf('%f is not present in the data, interpolating\n',Pi) ;

Rvi = interp1(P,RV,Pi) ;

Di = interp1(P,D,Pi) ;

iwant = [Pi RVi Di] ;

end

fprintf('Pressure = %f, R.V = %f, Liq.Density = %f\n',Pi,RVi,Di) ;

Answer 1

[Image Analyst]

What do you want to be an input argument? The filename? The Pi value? Any other values? Something like this maybe

function iwant = ComputeValues(filename, Pi)
iwant = []; % Initialize
[num,txt,raw] = xlsread(filename) ;
P = num(:,1) ; 
RV = num(:,2) ;
D = num(:,3) ;
% Pick a pressure value 
Pi = str2double(Pi) ;
tol = 10^-3 ;
idx = abs(P-Pi)<=tol ;   % check is Pi present in data
if any(idx)
    fprintf('%f is present in the data\n',Pi) ;
    Pi = P(idx) ; 
    RVi = RV(idx) ; 
    Di = D(idx) ;
else
    fprintf('%f is not present in the data, interpolating\n',Pi) ;
    Rvi = interp1(P,RV,Pi) ;
    Di = interp1(P,D,Pi) ;
end
iwant = [Pi, RVi, Di];
fprintf('Pressure = %f, R.V = %f, Liq.Density = %f\n', Pi, RVi, Di) ;

[ML]

I want the input argument to be the "user input" pi, as for the file I just need it there so it can be compared to the input. Sorry not sure if that makes sense....

[Image Analyst]

You can certainly use the input() function wherever you want to get a value for Pi or any other variable. You can use it both in your main program before you call the function to get input argument values that you are going to pass. You can also use it in the function if you need to get additional values.