No, I'm saying that someone like Donald Knuth is obligated, by the terms of his employment as a premier academic, to sit on the cutting edge of both mathematics and computer science.
/u/dxbydt commented on this very well, so I'll only reinforce the point that not everyone is Donald Knuth. If the distinction between DS and Engineer is blurred in your specific instance, and you're capable of Knuth-ian levels of work in both, you are almost certainly underpaid and need to lead a team or start a company yourself, stat, since a top-tier combination of those skills is exceedingly rare.
/u/dxbydt commented on this very well, so I'll only reinforce the point that not everyone is Donald Knuth. If the distinction between DS and Engineer is blurred in your specific instance, and you're capable of Knuth-ian levels of work in both, you are almost certainly underpaid and need to lead a team or start a company yourself, stat, since a top-tier combination of those skills is exceedingly rare.