Since the port to kirigami 2, plotting doesn't work in kalgebra-mobile. Clicking the '+' icon doesn't do anything and throws an error: file:///usr/lib/qt/qml/org/kde/kirigami.2/private/ActionButton.qml:125: TypeError: Type error
This is an issue in Kirigami 2.0.0 and is fixed for 2.1.0.