[Tex/LaTex] Power indices on the left side

math-modepositioningspacing

I'm using {^2K} to write the indices on the left side, but when I do so I get an unwanted space between 2 en K. Is there another way to write the "power" indices on the left side?

\section*{text}
\fbox{\parbox{38em}{
\textbf{text} 
\textit{text}
\begin{eqnarray}
f^{(M)}(z)\underbrace{(K_1,K_2,\ldots,K_M)}_\text{operandi}= \sum\limits_{i=1}^m \sum\limits_{j_1=1}^m \sum\limits_{j_2=1}^m \ldots \sum\limits_{j_M=1}^m {^if_{j_1 j_2\ldots j_M}}{^{j_1}K_1}{^{j_2}K_2}\ldots{^{j_M}K_Me_i},
\end{eqnarray}
waarbij $z$ het argument is en
\begin{eqnarray}
K_t &=& [{^1K_t, ^2K_t,\ldots, ^mK_t}]^T \in \mathbb{R}^m, \qquad t = 1,2,\ldots,M, \nonumber \\
{^if_{j_1 j_2\ldots j_M}} &=& \frac{\partial^M{^if(z)}}{\partial^{j1}z\partial^{j2}z\ldots\partial^{jM}z},
\end{eqnarray}
}

The result that I get is this

I'd like to make the sapce there smaller, or to write {^2K_t} in another away.

PS how can I remove the unwanted space here

Best Answer

You can use the command \prescript of the maththools package.

See the following minimal working example:

\documentclass{article}

\usepackage{mathtools}

\begin{document}

\begin{equation*}
    \prescript{2}{}{K}
\end{equation*}

\end{document}
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