I need to save a value stored in a variable in a matlab function in a separate Excel file

I have a MATLAB code that has three four functions to solve a couple partial differential equation system. I need to find a way to save the values stored in a particular variable in a separate excel file. I need to save the values of (Ke)*DuDx(1)/g in line 63 and (u(1)-u(2) in line 64 in separate variables and obtain them as output so that I can save them in separate excel files.

The code is given below

function pde_TwoTemperature_solve 
% pde_TwoTemperture_solve    
clear 
format long 
m =0; 
x=0:10e-10:50e-9; 
t=0:100e-15:1e-12; 
%%--------------------------------- 

[sol] = pdepe(m,@pdex5pde,@pdex5ic,@pdex5bc,x,t); 
Te = sol(:,:,1); 
Tp = sol(:,:,2); 
save('electron_temperature.mat','Te')
save('phonon_temperature.mat','Tp')
figure
surf(x,t,sol(:,:,1))
title('Electron Temperature')
xlabel('Space')
ylabel('Time')
zlabel('Temperature')
figure
surf(x,t,sol(:,:,2))
title('Phonon Temperature')
xlabel('Space')
ylabel('Time')
zlabel('Temperature')
% --------------------------------------------------------------------------   

function [c,f,s,d] = pdex5pde(x,t,u,DuDx) 
%function [c,f,s,uMinusV,KeDuDx] = pdex5pde(x,t,u,DuDx)
%------------Au----------- 
g=1e17;
rho=8.96e3;
Ce=96.8;
Ci=3.62e6;
delta=15.3e-9;
tao=100e-15; 
F=17;
alpha=398; 
beta=0.16; 
Tf=6.42e4; 
tp=100e-15;
w0=650e-9;
tp=200e-15;
tee = 200e-15;
Ke=alpha*(u(1)/u(2));
Kl=7;
xx=500e-9;

dt=200e-15;
%S=(((0.49*F)/(delta*(tp+tee))) * (exp(-2.77 * (((t) - (2 * (tp + tee))) / (tp + tee))^2))); 
S=(0.94*F/((tao*(delta+100e-9))*(exp(-x(end)/(delta+100e-9)))))*(exp((-x/(delta+100e-9))+(-2.77*((t/tao).^2))));;%Ë«Âö³åÌ弤¹âÔ´Ïî 
%%%---------------%%%%%%%------------------------- 
c = [Ce*u(1)/g;   Ci/g];                               
f = [ (Ke)*DuDx(1)/g;   (Kl)*DuDx(2)/g]; 
s1 = -(u(1)-u(2))+S/g; 
s2 =(u(1)-u(2));  
s = [s1; s2]; 
% --------------------------------------------------------------------------   
function u0 = pdex5ic(x) 
u0 = [300; 300]; 
% save u(1)-u(2) and (Ke)*DuDx(1)/g to separate arrays


% --------------------------------------------------------------------------   
%function [pl,ql,pr,qr] = pdex5bc(xl,ul,xr,ur,t) 
%hep = 5e9;
%hpp = 500e6;
%pl = [0; 0];                                   
%ql = [1; 1];                                   
%pr = [hep*(ur(1)-300); hpp*(ur(2)-300)];                                   
%qr = [1; 1];  
%------------------------------------------------------------------------------
function [pl,ql,pr,qr] = pdebc(xl,ul,xr,ur,t)
pl = [0;ul(1)];
ql = [300;300];
pr = [ur(1)-300;ur(2)];
qr = [300;300];  

%[uMinusV, KeDuDx] = pdex5pde(x,t,sol(:,:,1),sol(:,:,2));
%dlmwrite('uMinusV.txt', uMinusV, 'delimiter', '\t');
%dlmwrite('KeDuDx.txt', KeDuDx, 'delimiter', '\t');

Answer 1

[Image Analyst]

You need to create your output inside the function then return it to the calling routine:

function output = pde_TwoTemperature_solve 

If you want to save something in a file, there are lots of functions for that, like save(), writematrix(), fprintf(), etc.

[Pravin Karna]

Can you please elaborate a bit. where do we create the output. I tried creating an extra output arguement in the pdex5pde function to save the values but how to call them in the main function. The output are not saved in the sol maatrix where Te and Tp are only stored I did something like this

function [c,f,s,d] = pdex5pde(x,t,u,DuDx)

%function [c,f,s,uMinusV,KeDuDx] = pdex5pde(x,t,u,DuDx)

%------------Au-----------

g=1e17;

rho=8.96e3;

Ce=96.8;

Ci=3.62e6;

delta=15.3e-9;

tao=100e-15;

F=17;

alpha=398;

beta=0.16;

Tf=6.42e4;

tp=100e-15;

w0=650e-9;

tp=200e-15;

tee = 200e-15;

Ke=alpha*(u(1)/u(2));

Kl=7;

xx=500e-9;

dt=200e-15;

S=(((0.49*F)/(delta*(tp+tee))) * (exp(-2.77 * (((t) - (2 * (tp + tee))) / (tp + tee))^2)));

%S=(0.49*F/((tao*(delta+100e-9))*(exp(-x(end)/(delta+100e-9)))))*(exp((-x/(delta+100e-9))+(-2.77*((t/tao).^2))));;%Ë«Âö³åÌ弤¹âÔ´Ïî

%%%---------------%%%%%%%-------------------------

c = [Ce*u(1)/g; Ci/g];

f = [ (Ke)*DuDx(1)/g; (Kl)*DuDx(2)/g];

s1 = -(u(1)-u(2))+S/g;

s2 =(u(1)-u(2));

s = [s1; s2];

d1=u(1)-u(2);

d2=(Ke)*DuDx(1)/g;

d=[d1;d2];

[Image Analyst]

I have no idea what's going on in this uncommented code. I have no idea which of those dozens of variables you consider to be the, or an, "output". Only you know that.