In [1]: latex(1/cos(x)) Out[1]: \operatorname{cos}^{-1}\left(x\right)

In [2]: pprint(1/cos(x)) 1
────── cos(x)

[1] should output \frac{1}{\operator ...}

It is not ease to fix, because it is related with "medium" issue 2552

In [1]: 1/cos(x) Out[1]: 1/cos(x)

In [2]: (1/cos(x)).args Out[2]: (cos(x), -1)

issue 2552: substitution does not work for (1/(x*y)).subs(x*y, 2) because :

In [15]: a = 1/(x*y)

In [16]: a.args Out[16]: ⎛1 1⎞ ⎜─, ─⎟ ⎝x y⎠

I don't think that's related. All that needs to be done here is to check the sign of the exponent. The logic can (and should) be copied from the pretty printer/string printer.

pull request 736

We have moved issues to GitHub https://github.com/sympy/sympy/issues.

Migrated to http://github.com/sympy/sympy/issues/5883