i'm using the {fei} class im my document and my preamble is pretty simple as follows
\documentclass[rascunho]{fei}
\usepackage[utf8]{inputenc}
\usepackage{gensymb}
\usepackage{cancel}
when using the \ref{} command to call an equation as in the example below, the resut is pretty much the expected:
\begin{equation}
\nu_{max} \propto T \Leftrightarrow \nu_{max}=Constante_{2}.T
\label{eq4}
\end{equation}
onde, para um corpo negro, a equação (\ref{eq3})
But when using the exact same command to call in a figure i get an error, the code go as following:
\begin{figure}[h!]
\center
\includegraphics[scale=0.9]{fig15.jpg}
\label{fig15}
\end{figure}
Any equation that i reference works perfectly fine, but every single figure i try use the same method shows this error, i read that compiling 2 or more times might be able to fix the issue, but i tried several times and it persists.
i'm pretty sure it must be something really simple and easy to fix, but cant find what no matter how much i try....
figure
environment without\caption
doesn't generate a number LaTeX can refer to. By the way you should use\centering
rather than\center
.siunitx
and input the value of the constant as\SI{2,898e-3}{\meter\kelvin}