hi. I want to draw the 3D PLOT of this but i can only draw 2-D. kindly help. I am new.

x = (0:(1/60):1);  % intial data as given by problem
m = length(x);
t = zeros(1,m);
t = (0:(1/60):0.5);
t(1, 32:61) = 0;

y = 40*sin(pi*x); % function vector
theta = [1; 0.2;0.8]; %initial theta

aplha = 0.1;

lambda = 2;

X = ones(m,3);

X(:,2) = x;

X(:,3) = t;

h_theta = X*theta;   
h_theta = h_theta';

% error 
J = 0;

for i = 1:m
    J = J + (h_theta(i)-y(i))^2;
end

J = J/(2*m) ;  % error using initial theta

Reg = lambda/(2*m) * sum(theta(2:3,1));

J = J + Reg

v = pinv(X'*X)*X'*y' % calculated perms




x1 = (0:0.25:1);
t1 = (0:0.1:0.4);

for i = 1:length(x1)
    pol(i) = v(1) + v(2)*x1(i) + v(3)*t1(i);
    
      
end

pol


plot3(x1,t1,pol, 'r-')

[Walter Roberson]

That is a 3D plot. It happens to be a straight line segment in 3D, which makes sense considering the way you construct the coordinates.

[rana zain]

i want my results to be like that. So help me change my coordinates please.

[rana zain]

can someone please answer my query. its urgent.

[Walter Roberson]

x1 = (0:0.25:1);

That is a row vector of length 5

t1 = (0:0.1:0.4);

That is a row vector of length 5

for i = 1:length(x1)
    pol(i) = v(1) + v(2)*x1(i) + v(3)*t1(i);   
end

That clearly calculates linear combinations. Another way of writing it would be

pol = v(1) + v(2)*x1 + v(3)*t1;

Now, you could potentially make a grid of x1 and t1 values, such as

[X1, T1] = meshgrid(x1, t1);
pol = v(1) + v(2)*X1 + v(3)*T1;
surf(X1, T1, pol, 'edgecolor', 'none')

However it is clear that with pol being a linear combination, that you would just get a plane out.

You will need to modify the way you calculate pol a fair bit in order to get anything like what you ask for.

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/29922-why-your-question-is-not-urgent-or-an-emergency

[rana zain]

Still i am not getting the required answer. the answer is supposed to look like this but i don't get the desired answer.

i have attached the question asked also. Can you guide me. what changes must be made?

[rana zain]

Can someone answer this query?

[Abdolkarim Mohammadi]

Those surfaces must be drawn with surf(), and it requires pol to be a matrix, not a vector.

[Walter Roberson]

No, no one can answer the query, not unless they happen to be taking (or giving) the same clasd this is homework for, and so can supply the missing information.

We cannot plot y because there is no equation for y in what you posted. Instead there are equations for the seemingly irrelevant f and g.

[rana zain]

the value of y is y= 40*sin(pi*x) as given in the problem. i still attached my whole question in pdf form.