This is Off Topic related to SMath but a good group here to ask...

Please suggest software that will function as a Math Editor.

For typing in math equations for printing or display (not for solving math like SMath)

I searched for "Math Editor" and found several commercial paid applications...

And a couple of "Open Source" programs including
Math Editor
MathCast


Couldn't find an active support forum for either of these so...
before I invested time in either of these I thought I would ask the folks here for your suggestions.

Open Source or "Free" is the preferred, of course.

For clarity when I ask about a "Math Editor" I'm referring to a program that will allow easy entry of all math symbols like you might see in a text book.

Thanks for any help.

The most complete and tested typographical composition system also suitable for mathematics (but not only) is the TEX from which the LATEX language and the Lualatex, PDFLATEX, Xelatex programs are descended, which allow you to obtain excellent mathematical documents in PDF.
You should refer to TexLive to get all the information and download the program that is complete but rather heavy. Then to write, you will need the documents, you will need an editor (a text editor is also sufficient but TexStudio recommend).
Even Smath had and perhaps still has (but they are not updated for a long time) two plugins to directly export the Latex and Xelatex (some features were not complete). The author of Smath has probably decided to abandon this way and point his resources on Smath Writer.

sergio