what visually looks like an "exponential equation" is in fact overlapping discrete lines and intersecting points. if you just leave the intersecting points and connect them with a line you will see that they don't exactly make a neat "exponential equation" graph but discrete line sections. Therefore there's so automatic program to turn the bunch of lines into an equation where the lines intersect. You could possibly use logic/proof (math) theory application to derive the equation where the lines get closer and closer together, but nothing automatic afaik. Each line is itself a simple gradient equation and has no (automatic) relationship to another line with a steeper gradient.