FloatMath has been removed in API 23

[Mygod]

http://developer.android.com/reference/android/util/FloatMath.html

Warning: net.simonvt.menudrawer.Scroller: can't find referenced method 'float sqrt(float)' in library class android.util.FloatMath

[ImranAtBhimsoft]

Add this line to you proguard file
-dontwarn net.simonvt.numberpicker.Scroller

Will fix your issue.

[Redman1037]

it should be -dontwarn net.simonvt.menudrawer.Scroller