I found the following interesting function and its analysis at Non-analytic smooth function article in Wikipedia. I include a screen capture below for those who don't wish to navigate away:
I could not find a clear reference in the article as to the source of this example. Hence my question:
Question: who found the example above ?
I found the Fabius function article gives another example of a smooth but nowhere analytic function after reading this great MSE question but I need a reference for the nameless example I post above. Thanks in advance for your insight on this matter.