How to save values in a specific position+stop output

I am using fzero to solve a non-linear function, and then using a for-loop to plot the function for different values of p.

volume=fzero(@(V) volume(V,P), fstart);

for P=5:1:15
    Volume=fzero(@(V) volume(V,P),fstart);
end

P=P+1;

plot(Volym)

Several questions;

How do i stop the loop from displaying every value of 'Volume' in the command window? The ';' in the loop doesnt seem to stop this.

How do i get the Volume loop to store the values in a 1x10 double, starting with P=5 on the first and P=15 on the tenth? Currently, the loop saves the first 5 (for P=0 until P=4 as zeros, which makes the Volume expression a 1x15 double instead. So essentially i need a way to ignore the first 5 columns.

Answer 1

[madhan ravi]

You need to upload your missing parts of your code to be debugged:

volume=fzero(@(V) volume(V,P), fstart);
P=5:15;
Volume=zeros(size(P)); % preallocate
for i=1:numel(P)
    Volume(i)=fzero(@(V) volume(V,P(i)),fstart);
end
plot(Volym)

[Maximilian Jatzkowski]

The attached documents are my code and my function (sorry for the swedish language comments). If i use what you commented above, i get a 1x11 double, but the subsequent plot only goes from P=5 to P=11. I still need the volym-function to be plotted from P=5 to P=15

[Maximilian Jatzkowski]

Thanks! Replacing helped with getting unneccessary outputs! :)

now i still have trouble with my volym output being a 1x15 double and not a 1x10 double.

Just to clarify, i want Volym to only include values of fzero for P=5 to P=15.

How do i fix this?

[madhan ravi]

P has only 11 points :

n=2;
a=1.360;
b=0.003183;
R=0.0821;
T=300;
P=5;
% fplot(@(V) volym(V,P),[0 0.1]);
fstart=0.1;
P=5:15; % if you want 15 points then try linspace(5,15,15)
Volume=zeros(size(P)); % preallocate
for i=1:numel(P)
    Volume(i)=fzero(@(V) volym(V,P(i)),fstart);  % function call
end
Volym=volym(Volume,P);
xx=linspace(P(1),P(end),1000);
yy=interp1(P,Volym,xx,'spline'); % for a smooth curve
plot(P,Volym,'o',xx,yy)
% axis([5 15 0.1 0.12])
title('Volume dependent on Pressure')
xlabel('Pressure')
ylabel('Volume')
 
function Volym=volym(V,P)  % function definition
n=2;
a=1.360;
b=0.003183;
R=0.0821;
T=300;
Volym=(P+(a.*(n./V).^2)).*(V-(n.*b))-n.*R.*T;
end

The graph :

Note: I still have no idea what you are trying to do but clarify.

[madhan ravi]

If it’s what you were looking for make sure to accept the answer else let know.