Hello, I am trying to formulate QP in cvx, it is from the officical example, `` Exercise 4.3: Solve a simple QP with inequality constraints’’ . The code is as follows,

% From Boyd & Vandenberghe, “Convex Optimization”

% Joëlle Skaf - 09/26/05

%

% Solves the following QP with inequality constraints:

% minimize 1/2x’*P*x + q’*x + r

% s.t. -1 <= x_i <= 1 for i = 1,2,3

% Also shows that the given x_star is indeed optimal

% Generate data

P = [13 12 -2; 12 17 6; -2 6 12];

q = [-22; -14.5; 13];

r = 1;

n = 3;

x_star = [1;1/2;-1];

% Construct and solve the model

fprintf(1,‘Computing the optimal solution …’);

cvx_begin

variable x(n)

minimize ( (1/2)*quad_form(x,P) + q’*x + r)

x >= -1;

x <= 1;

cvx_end

fprintf(1,‘Done! \n’);

When I run it, the error prompted is ``The funtion ‘vec’ corresponding to input paramenters of type ‘double’ is not define ‘’.

I found that both the ‘cvx-funtion’ folder and ‘cvx-funtion-@cvx’ folder contained a ‘quad_form.m’ function. The ‘quad_form.m’ in ‘cvx_funtion’ was supposed to be called during runtime, but the ‘quad_form.m’ in ‘@cvx’ was called.

I don’t know how to solve it.

Thank You.