Is it possible to change the app launched by the Calculator button in iOS 7? iOS 7 introduced the swipe-up Control Center which has a dedicated Calculator button (on iPhone, but not iPad). For those of us who consider the default four-function Calculator app inadequate, is there a way to make that button launch a different calculator app instead?

If applicable, jailbreak answers are valid but I'm looking for a non-jailbreak solution.
No. 

These apps would then also accessible from the lock screen which would open a whole can of worms about security. Even the standard Apple apps do have problems with that sometimes, it would be even worse with 3rd party apps.