select the optional second function to display (yellow) 
  This box is shown only in the case the profile contains another function depending on selected variable.
  This function is plotted dependently. It means it has exactly the same scale and position as the main function.
  The dependence mentioned above allowes precise observing of relations between the functions.
  The definition domain of this function is not expressed. Please switch the functions if it is required.

Notice:  It is possible that there are functions of very different scales to plot together.
My recommendation is: transform one of them appropriately and show this transformed one. There are probably enough names (26 total) in the profile to do that.
For example:
         vertical enlarging 100 times: use 100*(sin(x) + x^3) instead of sin(x) + x^3.
         horizontal enlarging 10 times: use sin(x/10) + (x/10)^3 instead of sin(x) + x^3.
strom