There is an app called MyScript Calculator available both on Android and iOS. It does the same thing perfectly and fine. Apple is copying their ideas. As an Asian, I barely use it (for finding log and trig values). I like it because it gives a pen-pencil feeling. The first release of the app was about 11 years ago (ain't sure) and after that, they released version 2 which was more advanced and able to handle advanced mathematics. It didn't need extra RAM, memory and stuff at that time. I'm not judging or criticising Apple, and neither I'm the developer of the app (I'm not the creator). I'm just thinking if you took someone's idea, why not at least give credit to the original ideator? or tell the people that it's inspired by the XYZ company or the company where the product originated from.