Plot an equation by calling a function

Hi.

I tried to write a function and then call it to plot me y , it didn;t work out . could you please tell me what is wrong with it ?

Here is the function :

function [y]=myfunn(m,c,k,x0,v0,t)
w0=sqrt(k/m);
zeta=c/(2*sqrt(k*m));

if(zeta>0 && zeta<1)
y=(exp(zeta.*(-1).*t)).*((x0.*cos(w0.*sqrt(1-zeta.^2).*t))+(v0+zeta.*w0.*x0).*sin(sqrt(1-zeta.^2).*t)./(w0.*sqrt(1-zeta.^2)));

elseif(zeta==1)
y=(exp(zeta.*(-1).*t)).*(x0+t.*(zeta.*w0.*x0));


elseif(zeta>1)
y=(exp(zeta.*(-1).*t)).* ...
(((v0+(zeta+sqrt(zeta.^2-1)))).*exp(w0.*sqrt(zeta.^2-1).*t)./2.*w0.*sqrt(zeta.^2-1)  + ...
 ((-v0+(-zeta+sqrt(zeta^2-1))))*exp(-1*w0.*sqrt(zeta.^2-1).*t)./2.*w0.*sqrt(zeta.^2-1));

end
      
end

And here is the script when I tried to call it and then plot it :

clc
clear
close all
m=input('Please enter mass : ')
c=input('Please enter damping : ')
k=input('Please enter stifness : ')
x0=input('Please enter x at t=0 : ')
v0=input('Please enter v at t=0 : ')
t=input('Please enter time : ')
[y]=myfunn(m,c,k,x0,v0,t);
t=linspace(0,t,100);
plot(t,y)
xlabel('time')
ylabel('x(t)')
grid on
hold on 

Maybe I am wrong in calling a function ask ask it to plot .... Idk

[Walter Roberson]

@Fatemeh Salar

You have marked this as duplicate. What is the link to the other post that it is a duplicate of?

[Fatemeh Salar]

@Walter Roberson I changed the entire question and now wanted to delete it . I post it again here , so I flagged this question to get deleted (apperantly I can't delete it by myself)

Thanks.

[Rik]

You received an answer. That is why you can no longer delete it. Materially editing your question will only make it confusing for future readers with a similar question.

Asking a second question is not a problem, but why mutilate the first question in order to do so?

Answer 1

[KSSV]

It looks like your e in the function is exp. Change the function to:

function [y]=myfun(a,b,c,t)
if (a*b/c>1)
    y = (exp(a))*sin(c.*t)./sqrt(b);
elseif (a*b/c<1 && a*b/c>0)
    y = sin(a)*sqrt(b.*t)./sin(c);    
elseif (a*b/c < 1)
    y = cos(a)*exp(b.*t)./c;
end
end

If e is not exp, then you need to define e like a,b,c and input into the function.

[Fatemeh Salar]

@KSSV I forgot to put e=3.14 , still it ain't work ....

Matter of fact my function works (it provide me a number as y) but it can't plot anything .

[KSSV]

Use the function which I gave. It works.

[Fatemeh Salar]

@KSSV

My bad! I think I asked a question I already knew its answer lol

The thing is I made a mistake at the first place. There was an error for another function of mine not that one you saw earlier. So instead of deleting my previous question I edited it.

The proplem is with my function [y]=myfunn(m,c,k,x0,v0,t)

And the picture was the result of this function that ain't working :S