A problem with recalling a function

So I have a code, that calculate the output voltage at the three Nodes of an RC Circuit based on the user's Input frequncy.. ( one of three, 1Hz, 8Hz, or 20Hz) .. And the user had only 3 choices, And i designed it using the following errorflag

errorflag = 0;

while (errorflag == 0)

disp(' ')

disp ('Which Frequency do you want to use?')

disp (' (1) 1Hz ')

disp (' (2) 8Hz')

disp (' (3) 20Hz')

freq_choice=input('Please enter choice (1, 2, 3) > ');

disp(' ')

% check for valid input

if( freq_choice == 1 || freq_choice == 2 || freq_choice == 3)

errorflag =1;

else

disp(' *** Invalid choice ')

disp(' *** Please respond with a 1, 2, or 3 ')

disp(' *** Press ENTER to continue ' )

pause

end % if

end % while

Based on the user input, let's assume he chose 1Hz, the output would be a subplot of the output voltage at Node1, Node2, and Node 3.. with 1Hz frequncy.

Now I want to improve the code a bit, expanding the choices to 6 as shown below

errorflag = 0;

while (errorflag == 0)

disp(' ')

disp ('Which analysis do you want to make?')

disp (' (1) Using 1Hz freq across all three Nodes (1&2&3) ')

disp (' (2) Using 8Hz freq across all three Nodes (1&2&3)')

disp (' (3) Using 20Hz freq across all three Nodes (1&2&3)')

disp (' (4) At Node1 ONLY across all three Freq (1Hz & 8Hz & 20Hz)')

disp (' (5) At Node2 ONLY across all three Freq (1Hz & 8Hz & 20Hz)')

disp (' (6) At Node3 ONLY across all three Freq (1Hz & 8Hz & 20Hz)')

freq_choice=input('Please enter choice (1, 2, 3,4,5,6) > ');

disp(' ')

% check for valid input

if( freq_choice == 1 || freq_choice == 2 || freq_choice == 3 || freq_choice == 4 || freq_choice == 5 || freq_choice == 6)

errorflag =1;

else

disp(' *** Invalid choice ')

disp(' *** Please respond with a 1, 2, 3, 4, 5 or ')

disp(' *** Press ENTER to continue ' )

pause

end % if

end % while

And I want to design a function, that takes two inputs from the user .. freq ( the input frequency) and nd (the node number, 1 ,2 or 3) .. (I was not sure about posting the whole code, so I added (......) replacing the circuit formulation part, and left the part that's connected with the two vraibles i wasnt ( freq , nd)

function dc=requiredgraph (freq, nd)

% Declare the number of the nodes and Matricies from the circuit nodal formulation (G ,C ,B)

......

% Our simulation conditions { End time (T) / Number of Points (N) }

......

% The Initial Conditions

......

% Time Vector, based on the Number of Points (N)

.......

%Definining the Input Voltage based on Freq

for i=1:N

Vin(i)=cos(2*pi*freq*t(i));

end

% Solve For V using the Time March Technique

V(:,1)=Vo;

for i=2:N

V(:,i)=((C+G*dt))\(C*V(:,i-1)+B*Vin(i)*dt);

%plotting the function

figure

plot(t,V(nd,:));

title('The Output voltage at Node2, at Frequency of 1Hz');

xlabel('Time');

ylabel('The Output Voltage');

grid on

end

end

Now, if i want to recall this function to plot the graph of output at Node 2 ( nd=2) and Freq of 8Hz ( freq=8) .. How can I do this? Sorry for the long question, and please let me know if there is any missing info.

Thanks in advance. And help is highly appreictated

[Abdelrhman Abdelfatah]

I think i would aslo need to re formulate the figure title to be depending on the user input Freq and the picked nd(Node number), is that even possible?

[Dr. Kelsey Joy]

I recommend revising how you prevent your user from proceeding based on their input. Here is some sample code to help you out with your errorflag portion of code: https://www.mathworks.com/matlabcentral/fileexchange/102674-educational-validating-user-inputs-numbers-and-strings?s_tid=prof_contriblnk

Answer 1

[Abdelrhman Abdelfatah]

Okay I fixed it, by making the output figure, and recalled the function name in another code, and it worked perfectly

function dc=requiredgraph (freq, nd)

% Declare the number of the nodes and Matricies from the circuit nodal formulation (G ,C ,B)

......

% Our simulation conditions { End time (T) / Number of Points (N) }

......

% The Initial Conditions

......

% Time Vector, based on the Number of Points (N)

.......

%Definining the Input Voltage based on Freq

for i=1:N

Vin(i)=cos(2*pi*freq*t(i));

end

% Solve For V using the Time March Technique

V(:,1)=Vo;

for i=2:N

V(:,i)=((C+G*dt))\(C*V(:,i-1)+B*Vin(i)*dt);

%plotting the function

dc=figure

plot(t,V(nd,:));

title('The Output voltage at Node2, at Frequency of 1Hz');

xlabel('Time');

ylabel('The Output Voltage');

grid on

end

end