Hi,

I'm planning to generate a sin tone in a given frequnecy and length then apply fade-in effect to beginning of this tone and fade-out effect to end of this tone. And finally save this tone to wav file. Is it possible with pure data? Is there any example?

Look here for a lesson on generating the tone:

http://pd-tutorial.com/english/ch03.html#id420457

Saving the file can be done with either [writesf~] or [soundfiler].