How can i display a funtion dependenet to x ?

Hi How can i can i display f with values in function of x ?

L=3;

sol(1)=2;

psi=1;

f (x) = @(x) cos ( (sol(1)/L) *x)- cosh( (sol(1)/L) *x)+ psi *( sin( (sol(1)/L) *x)- sinh( (sol(1)/L) *x));

Answer 1

[Star Strider]

This works:

L=3;
sol(1)=2;
psi=1;

f = @(x) cos ( (sol(1)/L) *x)- cosh( (sol(1)/L) *x)+ psi *( sin( (sol(1)/L) *x)- sinh( (sol(1)/L) *x));

x = linspace(-10, 10);

figure(1)
plot(x, f(x))
grid
xlabel('x')
ylabel('f(x)')

See the documentation for the linspace function to understand how to change the limits and number of elements in the ‘x’ vector.

[Mallouli Marwa]

If i want to display f when x=[0:L], i obtain this error :

Subscript indices must either be real positive integers or logicals.

Please help me

[Torsten]

I would be surprised if you get this error if you simply replace

x = linspace(-10, 10);

by

x = linspace(0, L);

in Star Strider's code.

Best wishes

Torsten.

[Mallouli Marwa]

How can i determine the expression of df(x)/dx ?

Please other solution then diff.

[Torsten]

Then I only see the "pencil and paper" solution.

Best wishes

Torsten.

[Star Strider]

Thank you, Torsten. I’m UTC-7 here. I appreciate your comments.

A numeric evaluation of df(x)/dx would be the gradient function.