# Bold symbol in math-mode, but normal subscript?

I want my subscript on F in the first equation to be like the subscript on A in the second equation.

I've tried to use \emph{ } to override the bolding, but this makes the spacing and sizing of the subscript smaller/closer together than that for A.

\documentclass{article}
\usepackage[fleqn]{amsmath}

\begin{document}

\begin{gather}
Y_i = \bf{F}_{ij} \bf{B} + e_{i}\\
Y_i = A_{ij} = 1,2,...,N \notag
\end{gather}

\end{document}

-

\bf is incorrectly used here; use \mathbf, which takes a parameter to set it in bold font:

\documentclass{article}
\usepackage[fleqn]{amsmath}% http://ctan.org/pkg/amsmath
\begin{document}

\begin{gather}
Y_i = \mathbf{F}_{ij} \mathbf{B} + e_{i}\\
Y_i = A_{ij} = 1,2,\dotsc,N \notag
\end{gather}

\end{document}


As a side note, amsmath provides \dotsc for a math-related \ldots between commas. See section 4.3 Dots (p 11 & 12) of the amsmath documentation for all kinds of math-related dot-commands.

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Nice. Why do you use \dotsc over "..."? –  user16208 Aug 23 '12 at 4:16
@IssacM: I've added some reference to \dotsc in the amsmath documentation. –  Werner Aug 23 '12 at 4:19