I am wondering which research communities use the notation $\mathbf i$, $\mathbf j$, $\mathbf k$ for the three-dimensional unit vectors. The calculus textbook I have to use (Stewart) uses that notation. But I am a mathematician, so maybe there is a physics or engineering community out there where that notation is actually used.

Notations that I am well acquainted with include

• $e_1$, $e_2$, $e_3$
• $e_x$, $e_y$, $e_z$
• $\mathbf e_1$, $\mathbf e_2$, $\mathbf e_3$
• $\mathbf e_x$, $\mathbf e_y$, $\mathbf e_z$
• ...

I have never seen $\mathbf i$, $\mathbf j$, $\mathbf k$ in any research paper ever.

I am wondering which research communities use the notation $\mathbf i$, $\mathbf j$, $\mathbf k$ for the three-dimensional unit vectors. The calculus textbook I have to use (Stewart) uses that notation. But I am a mathematician, so maybe there is a physics or engineering community out there where that notation is actually used.

Notations that I am well acquainted with include

• $e_1$, $e_2$, $e_3$
• $e_x$, $e_y$, $e_z$
• $\mathbf e_1$, $\mathbf e_2$, $\mathbf e_3$
• $\mathbf e_x$, $\mathbf e_y$, $\mathbf e_z$
• ...

I have never seen $\mathbf i$, $\mathbf j$, $\mathbf k$ in any research paper ever. Can you point out a recent example?