Re: figura centrata in documento in due colonne

EDIT:
Allego un esempio minimo compilabile:`\documentclass[twocolumn]{article}
\usepackage{lipsum}
\usepackage{tikz}
\begin{document}
\lipsum[1-5]
\begin{figure*}[t]
\centering
\begin{tikzpicture}
\draw[help lines] (0,0) grid (3,2);
\pgfsetcornersarced{\pgfpoint{5mm}{5mm}}
\pgfpathrectanglecorners{\pgfpointorigin}{\pgfpoint{3cm}{2cm}}
\pgfusepath{stroke}
\end{tikzpicture}
\caption{Figura di prova centrata}
\end{figure*}
\lipsum[1-6]
\end{document}`