I am trying to plot freq vs max(x)/max(y) values for the following data. But I am having an error as shown below.Can anyone help me with this.

% file 1

for f=1:100

t = [0:0.01:2];

x0 = [0;0];

[t,x]=ode23('for1', t, x0);

[val,idx] = max(x) ;

fr(f)=f;

val(f)=val;

hold on

end

plot(fr,val/0.001,'*r')

%file 2

function f = for1(t,x)

c = 376.9900;

k = 7.1061e+05;

Y = 0.001;

f=zeros (2,1);

f(1) = x(2);

f(2) = -(c*x(2)/5)-(k.*x(1)/5)+((k/5).*Y.*sin(2.*pi.*f.*t))+( (c/5).*Y*2*pi.*f.*cos(2*pi.*f.*t));

end

Unable to perform assignment because the

left and right sides have a different

number of elements.

%ERROR

Error in for1 (line 8)

f(2) =

-(c*x(2)/5)-(k.*x(1)/5)+((k/5).*Y.*sin(2.*pi.*f.*t))+(

(c/5).*Y*2*pi.*f.*cos(2*pi.*f.*t));

Error in odearguments (line 90)

f0 = feval(ode,t0,y0,args{:}); % ODE15I

sets args{1} to yp0.

Error in ode23 (line 114)

odearguments(FcnHandlesUsed,

solver_name, ode, tspan, y0, options,

varargin);

Error in test1 (line 4)

[t,x]=ode23('for1', t, x0);

Required Output:

[Jesus Sanchez]

Please format your code properly! It's difficult to see it otherwise. The error is that the result of this:

f(2) =
    -(c*x(2)/5)-(k.*x(1)/5)+((k/5).*Y.*sin(2.*pi.*f.*t))+(
    (c/5).*Y*2*pi.*f.*cos(2*pi.*f.*t));

is a vector, as the input variable t is also a vector. You are assigning it to a "single nomber", which is f(2). You should modify it, either by allowing f to have a matrix form or using a for loop to give one value of t each time.

[Ketha Jaya Sandeep]

Thank you Mr.Jesus Sanchez for your support.

I rectified that error, but I am encountering a new error with the following code.

x0 = [0;0];

for f=1:100

for tspan=0:0.01:2

[t,x]=ode23('for1', tspan, x0);

end

[val,idx] = max(x) ;

fr(f)=f;

val(f)=val;

hold on

end

plot(fr,val,'*r')

ERROR

Error using odearguments (line 83)

The last entry in tspan must be different from the first entry.

Error in ode23 (line 114)

odearguments(FcnHandlesUsed,solver_name, ode, tspan, y0, options,varargin);

Error in test1 (line 4)

[t,x]=ode23('for1', tspan, x0);

[Jesus Sanchez]

I am sorry, I have never worked with ode23 before, so I am not sure how to help you further :(. From the error message, it seems that tspan must be a vector, so you will have to work under this assumption and modify your function consequently.