function command hellp

I have a function file have code like this

--------------------------------------------

function GH = Gibbs(R,T,Z,A,B)

% Calculate the Enthalpy, Enropy, Gibbs free energy
GH = R*T*((Z-1)- log(Z-B)- A/B*log(Z+B/Z));

end

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I have values of R, T, Z, A, B in another m-file , how I compute this by calling the other file for the values of R,T,Z,A,B

Answer 1

[Honglei Chen]

Let's say the other file is foo.m, then you can modify the signature of foo to return those values, e.g.

function [...,R,T,Z,A,B] = foo(...)

Then you can call them in sequence like this:

[...,R,T,Z,A,B] = foo(...);
GH = Gibbs(R,T,Z,A,B);

[Nasir Qazi]

wht are these dots ?

[Honglei Chen]

Those are whatever the original inputs and outputs are. If you don't have inputs and outputs, then it will reads like [R,T,Z,A,B] = foo

[Nasir Qazi]

I really dont get that, The values or R, is fixed and rest of then are varying ... and the other file is not a function file and the file have values like R=1.2 and others T,Z,A,B are variable values depend on R. now I want to caluclate GH byt getting values from that other file who have the values of R,T,Z,A,B , could you not mind to write it in proper order in codes so i understand whats going on.thanks

[Nasir Qazi]

r u there/?

[Honglei Chen]

I'm starting a new answer

Answer 2

[Honglei Chen]

Then I will rewrite the other file into a function, using signatures like

function [T,Z,A,B] = foo(R)

Once you do that, you can call them in order

[T,Z,A,B] = foo(R)
GH = Gibbs(R,T,Z,A,B)

[Nasir Qazi]

this is not seems to be working , can I give you my codes

[Nasir Qazi]

this is not seems to be working , can I give you my codes

[Nasir Qazi]

% This is the first file

% P = RT / V - b - alpha*a / V(V-b)

R = 8.314e-3; % MPa m3 / mole.K

n = 0;

Tr = 0.6

Tc = 540.13; % K

Pc = 2.74; % Mpa;

T = Tr*Tc;

w = 0.350;

Pn_i = 0.067;

m = 0.480+1.574*w -0.176*w^2;

al=(1+m*(1-Tr^0.5))^2;

a = 0.42748*((R*Tc)^2/Pc);

b = 0.08664*(R*Tc/Pc);

for i=1:100

% Z3 - Z2 + (A-B-B^2)Z-AB=0

A = (a*Pn_i*al)/(R*T)^2;

B = (b*Pn_i)/(R*T);

Z=roots([1 -1 A-B-B^2 -A*B]);

Zv_i=max(Z);

Zl_i=min(Z);

Zvc=isreal(Zv_i);

if Zvc == false

Zv_i=abs(Zv_i);

disp('error 1')

end

Zlc=isreal(Zl_i);

if Zlc == false

Zl_i=abs(Zl_i);

disp('error 2')

end

phiv_i=exp((Zv_i -1)-log(Zv_i -B)-(A/B) *(log((Zv_i+B)/Zv_i )));

phil_i=exp((Zl_i -1)-log(Zl_i -B)-(A/B) *(log((Zl_i+B)/Zl_i )));

Fv_i=Pn_i*phiv_i;

Fl_i=Pn_i*phil_i;

Error=(Fv_i-Fl_i);

if (abs(Error) < 10^-6);

disp(Pn_i) ;

break

else

n=n+1;

Pn = (Pn_i)*(phil_i/phiv_i);

Pn_i = Pn;

end

end

% Gibbs Free Energy

GH = R*T*((Zv_i -1)- log(Zv_i -B)-(A/B)*log(Zv_i + B/Zv_i));

disp('The values of Gh are: ')

disp(GH)

[Nasir Qazi]

% this is a function file , the values of R,T,Z,A,B is taken from first file

function GH = Gibbs(R,T,Z,A,B)

% Calculate the Enthalpy, Enropy, Gibbs free energy

GH = R*T*((Z-1)- log(Z-B)- A/B*log(Z+B/Z));

end

[Nasir Qazi]

I am waiting for your reply ?

[Honglei Chen]

It looks like you want to calculate GH for each iteration? If that's the case, you need to break your first file into two. One of them just supply T,Z,A,B from R and the other one runs the loop. Then you can have a similar one to do a loop and calculate GH.

[Nasir Qazi]

do this for me , just make the first file like this

R=1

T=20

A=3

B=1

R=4

--------------

%and the 2nd file like this

function GH = Gibbs(R,T,Z,A,B)

% Calculate the Enthalpy, Enropy, Gibbs free energy

GH = R*T*((Z-1)- log(Z-B)- A/B*log(Z+B/Z));

end

%the 2nd file will get the values of R,T,Z,A,B from first one .. does it make sense . just do this for me please

[Honglei Chen]

You have to use a function to transfer these values out of the first file. Did you ever try making the first file like

function [R,T,Z,A,B] = foo

R=1;

T=20;

Z=4;

A=3;

B=1;

[Nasir Qazi]

yes i did and what will be the 2nd file

[Honglei Chen]

That's your function. Then in the command line, do

[R,T,Z,A,B] = foo

and you should get those values

[Nasir Qazi]

I know that but I don't want to run it on command line , want to excute the results in another M-file and when I run it I can display the result u get my point

[Honglei Chen]

Then you can call it within the other file

function GH = Gibbs

% Calculate the Enthalpy, Enropy, Gibbs free energy

[R,T,A,Z,B] = foo;

GH = R*T*((Z-1)- log(Z-B)- A/B*log(Z+B/Z));

end

[Nasir Qazi]

thats it thats wht i am looking for. thx so much