I am trying to typeset some higher-order time derivatives using the dot notation, and I've noticed something strange. The expressions

```
$\dot y + y = \cos(\dot y)$
$\ddot y + y = \cos(\dot y)$
```

give the expected results. However,

```
$\dddot y + y = \cos(\dot y)$
$\ddddot y + y = \cos(\dot y)$
```

causes the higher derivative term to be slightly raised, see below. Any thoughts?

Here is my preamble:

```
\documentclass{article}
\usepackage{amsmath, amssymb, amsfonts, amsthm, fouriernc}
```

## Best Answer

The problem in placement stems from the fact that both

`\dddot`

and`\ddddot`

construct their arguments as`\mathop`

in order to place a "limit" on top of it. However,`\mathop`

centres its contents vertically on the math axis if the argument is a single character (see mathop shifts the baseline, DeclareMathOperator doesn't) - a feature.So, you should trick LaTeX in thinking it is actually more than a single character by adding (say)

`\hspace{0pt}`

:One can correct automatically the behavior by adding the following code after

`\usepackage{amsmath}`

: