# Bold upright i-hat and j-hat for vector notation

I am trying to typeset a vector with i-hat and j-hat components:

\documentclass{article}

\usepackage{amsmath}
\usepackage{mathtools}

\newcommand{\ihat}{\mathbf {\hat \imath}}
\newcommand{\jhat}{\mathbf {\hat \jmath}}
\newcommand{\vect}[1]{\mathbf #1}

\begin{document}
\begin{align}
\vect{F} &= 3\ihat + 4\jhat
\end{align}
\end{document}

However, \imath and \jmath will always be italicized, no matter what modifiers I apply \mathbf, \mathrm, etc.

How do I make \imath and \jmath bold and upright?

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The \mathrm command has no effect on \imath or \jmath. LaTeX is smart enough to remove the dot on the i or j when adding a hat. –  Count Zero Sep 12 '11 at 14:07

For bold and upright, you could use the regular text-version of \imath and \jmath, which are \i and \j:

\newcommand{\ihat}{\hat{\textbf{\i}}}
\newcommand{\jhat}{\hat{\textbf{\j}}}

Additionally, if you want the \hat to be bold as well, then use \boldsymbol.

\newcommand{\ihat}{\boldsymbol{\hat{\textbf{\i}}}}
\newcommand{\jhat}{\boldsymbol{\hat{\textbf{\j}}}}

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\DeclareMathSymbol{\ii}{\mathalpha}{letters}{"10}
\DeclareMathSymbol{\jj}{\mathalpha}{letters}{"11}

\newcommand{\ihat}{\mathbf {\hat{\ii}}}
\newcommand{\jhat}{\mathbf {\hat{\jj}}}
\newcommand{\vect}{\mathbf}

The last line is a better definition of your \vect command.

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