How to get "f of A" pronounced with a long A ?

[steveTFC]

How can I get the en-us voice to say "f of A" and use a long A? I see that the en dictionary says to prounounce single letter "a" as a long A. Is there a rule that makes an exception for the phrase "of a"? How could I change this rule?

( In typing mathematical text to be used as audio, I type mathematical expressions such a "f(A)" as the words "f of A". )

[steveTFC]

I "cloned" the project, following directions in the youTube video "Increase Text to Speech pronunciation quality with eSpeak | Tutorial" by Thorsen-Voice. I edited the file en_list. Commented out the line " (of a) 0v0 $nounf " by preceding the line with two slashes. I recompiled the en language using "sudo espeak-ng --compile=en". That worked to pronounce "f of a" with a long 'a' when the sentence ends immediately after that.

To get "f of a" pronounced the way I wanted when the phrase doesn't end a sentence, I added the line "a eI" to the MAIN DICTIONARY section and recompiled.