Brunello Tirozzi

Adesso ti spedisco l’inizio del file latex con cui lavoro.
\documentclass[12pt]{article}
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\newcommand{\Pz}{\frac{\pa^2}{\pa z^2}}
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\title{On the solutions of Grad-Shafranov equation for the protosphera}

\author{ Paolo Buratti$^{1}$,Brunello Tirozzi$^{1,2}$, Franco Alladio$^1$, Paolo Micozzi$^1$\\
$^1$ Enea Research Center, Frascati, Italy\\ $^2$ Department of Physics, University La Sapienza of Rome, Italy}

\begin{document}

\maketitle

Let us start from the Grad-Shafranov equation

\begin{equation}
\Pz\psi+r \pr (\frac{1}{r}\pr \psi)=-r j_\phi
\end{equation}

where

$$j_\phi= r \frac{d p}{d \psi}+\frac{I_A(\psi) I_(\psi)^{‘}}{r}$$

where $I_A$ is an arbitrary flux function which takes the value $1$ outside the plasma region, \cite{Nucl.Fusion}, $p$ is the plasma pressure.

$$ I_A(\psi) I_A(\psi)^{‘}=K \psi \rightarrow I_A= K^2 \psi$$

The magnetic field is represented

E’ chiaramente un testo matematico e \Pz è stato accettato come risulta dal pdf ( guarda le prime righe. \Pz è stato definito come derivata seconda rispetto a z nel newcommand relativo. Il problema è sapere perchè debbo premere r per fargli prendere il \newcommand. Ti allego anche il file latex. Quando compili ti dà errore perchè non ti allego le figure. Non serve per questa discussione