eVX is a scientific calculation tool to quickly evaluate an arbitrary expression, using an algebraic form. You can combine a range of functions with up to 6 variables. The latest CODATA 2014 and IAU 2012 and 2015 fundamental and astronomical constants are included. The user can elect to use c.g.s. units (common in astrophysics) or the more standard S.I. Units.eVX for iOS is an adaptable small footprint app that works well with the new split screens in iOS9. A comprehensive custom keyboard allows rapid entry of any algebraic expression, and eVX also works well with any connected keyboards. eVX on OSX is called 'eValuator', and is a free app on the Mac Appstore.eVX works with iOS X 8.1 or newer including the latest iOS9 including the new iPhone 6s Plus and split screens on new iPads. It works on an iPhone 4s, but it is a bit of a squeeze, and eVX is designed for iPhone 5s or larger iPhones, and all iPads that support iOS 8.1 or newer, including the new iPad Pro.eVX is an OSX/iOS universal app. Available as a free app on OSX under the name Evaluator. Click the support link to find out how to find both versions.eVX is completely standalone, and does not access the network.- Enter any algebraic expression, using any set of the variables, numbers, the operators and functions below, and any of the builtin constants.- Optionally set up any of up to 6 variable values: x, y, z, t, a, or b.- The expression is evaluated as you type, with the answer appearing at the top.- There is no need for enter/return or equals buttons.- Green indicates a valid expression and answer.- The answer may be selected, copied, or shared as desired.- Expressions, and any constants or notes, can be saved in the scrapbook memory system.