I'm not sure about sin, cos and tan. To me it doesn't make a lot of sense to apply these operations to a 3D vector, the meaning is not obvious, and I can't think of good examples where doing component-wise sin/cos/tan would make sense.

In D6713#158901, @Brecht Van Lommel (brecht) wrote:

I'm not sure about sin, cos and tan. To me it doesn't make a lot of sense to apply these operations to a 3D vector, the meaning is not obvious, and I can't think of good examples where doing component-wise sin/cos/tan would make sense.

both GLSL and OSL support it, I've seen it used in noise generators, the book of shaders has a live example on this page

Although at first sight it doesn't make a whole lot of sense sin on a vector both OSL and GLS clarify in the documentation the operation will be performed component wise

The rationale for adding extra functions is to ensure that scalar/float and vectors have the same operators available. This is pretty standard in OSL, GLSL and Godot for example and makes sense from a user perspective.
The only downside I can see is that the menu is bigger but that can be addressed by another patch in the future. This is the reason for putting the vector specific functions at the start of the menu so they are immediately accessible and have the other functions match the float math node menu.
Whether the functions are useful can be left to the artist to explore. 😃

Godot visual shader, for example, exposes the same functions for scalar and vector values.
https://godotengine.org/article/major-update-for-visual-shader-in-godot-3-2

@Brecht Van Lommel (brecht) I was going to add faceforward as a function which needs the extra vector socket so it made sense to expose this to the wrap function. It gets hidden in the UI if it's not needed.

Do unused sockets impact Cycles/Eevee memory usage? Is that what you mean by overhead?

In Cycles SVM it adds overhead in that it will write the default value to the stack, then load it.

What you can do is add a separate SVM node for operations that use different parameters, even if the shares the same Cycles shader node.

In D6713#161284, @Brecht Van Lommel (brecht) wrote:

In Cycles SVM it adds overhead in that it will write the default value to the stack, then load it.

What you can do is add a separate SVM node for operations that use different parameters, even if the shares the same Cycles shader node.

Ok, that's useful, is there an example for this?

The UV map node is an example of this, but it's really just a matter of if/else in ::compile(SVMCompiler &compiler) and then adding another node in kernel/svm.

Cleaned warning in: 1bb7d42cf66