# trigonometry – How to cast this trigonometric polynomial into a convex function?

I’m trying to solve this minimization problem
begin{align} min frac{1}{2}vec{w}^top vec{w} end{align}
where
begin{align} vec{w} = begin{bmatrix} f_1 begin{bmatrix} mu sintheta\ mu costheta\ 1 end{bmatrix} + displaystylesum_{i=2}^n f_i begin{bmatrix} mu vec{r}_i^top [sintheta, costheta, -mu ]^top\ mu vec{v}_i^top [stheta, ctheta, -mu ]^top\ 1 end{bmatrix} end{bmatrix},quad thetain[0,2pi] end{align}
where $$theta$$ is the only variable and other vectors and scalars are given. Is it possible to recast this trigonometric polynomial into a convex function? Any help would be appreciated!