Allow tan to be used in df.eval.

[domsmrz]

• closes BUG: Unsupported operations #55091 (Replace xxxx with the GitHub issue number)
• Tests added and passed if fixing a bug or adding a new feature (not explicitly adding brand new tests but there are tests covering all the _unary_math_ops.
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.

[yuanx749]

While at it, is it feasible to also add other functions? I noticed the functions supported by NumExpr here, such as conj, real, imag.

[domsmrz]

While at it, is it feasible to also add other functions? I noticed the functions supported by NumExpr here, such as conj, real, imag.

Probably, but I'd prefer to keep this PR as is, since this is pure straight-forward fix.
Adding where is discussed here: #34834 .
I can imagine that adding complex-number operation should be easier than that but I'm not sure how well pandas handles them, so I'd prefer to delegate it to separate PR (at very least it would require adding tests)

[mroeschke]

Can you add a test for this?

[domsmrz]

Just by adding "tan" to the list _unary_math_ops a standard test (which is applied to all these functions) is automatically added:

pandas/pandas/tests/computation/test_eval.py

Line 1615 in 454e2e1

@pytest.mark.parametrize("fn", _unary_math_ops)

Let me know if you meant anything more specific.

[mroeschke]

Thanks @domsmrz