Help with plotting 3d function

Hey!

I need help with exercise 2.b. This is my script that i have written

%% Exercise 2.b

clear

clf

clc

k=1;

L=6;

T=10

x=linspace(0,L,100); t=linspace(0,T,100);

for i=1 : length(x)

for j=1 : length(t)

u(i,j)=(8/(pi^2)).*(1./(n.^2)).*sin(n.*pi/2).*cos(n.*pi.*t(j)/6).*sin(n.*pi.*x(i)/6);

end

end

surf(t,x,u)

xlabel('t'); ylabel('x')

The problem that i need help with is how to put in the value of n. In the exercise it says that i should put n between 1->100 but i dont know how to do it....

Could someone pleas help me...?

[Star Strider]

Note that n is the index with respect to , and your code does not appear to be doing that summation.

Answer 1

[Praveen Iyyappan Valsala]

Most intuitive way is to add another loop to sum up function outputs of all n.

for i=1 : length(x)
    for j=1 : length(t)
        for n=1:100
            u(i,j)=u(i,j)+(8/(pi^2)).*(1./(n.^2)).*sin(n.*pi/2).*cos(n.*pi.*t(j)/6).*sin(n.*pi.*x(i)/6);
        end
    end
end

Little more efficient way.

n=1:100;
for i=1 : length(x)
    for j=1 : length(t)
        u(i,j)=(8/(pi^2)).*sum((1./(n.^2)).*sin(n.*pi/2).*cos(n.*pi.*t(j)/6).*sin(n.*pi.*x(i)/6));
    end
end

if you want even more cool code. learn about meshgrid function.

[Jacob Andréasson]

Thank you so much!!!!