Pros: Excellent layout/colors. 2-line visible RPN stack! Multiple function sets

After searching for and downloading/paying for several RPN calculators, and as a previous user of the HP-48sx back in engineering college and the HP-32SII back in medical residency, allRPNcalc (version 2) is the first RPN calculator that deserves a spot on the front page of my iPhone as a worthy replacement of the functionality and feel of my still-functioning HP calculators. The overall design/layout/colors are well-planned, efficient, and basically beautiful - I keep turning on my iPhone just to look at allRPNcalc, which is an impressive demo app when showing off the features of the iPhone. Finally - an RPN calc with TWO levels of the (four-level) stack displayed! Why dont more RPN calcs do this? I would prefer seeing all 4 levels, but 2 is significantly better than 1. Plus you could always use the roll "R" button or press the information "i" button to see a full list of the stack and registers. And finally - a large "Enter" button! It seems the developers took all of the basic functionality of the old HP RPN calculators, but instead of simply duplicating appearance and multiple shift keystrokes and limited displays (as many other RPN apps do), they smartly modernized it to the iPhone platform.
    Additional features include display of the last operation in the upper right of the screen, easy change of the display output mode (including fractions) using the top green buttons, a triangle solver, built in help that lists the functions of all the keys, and unit conversions (including currencies) with an interesting scroll-wheel interface. The information "i" button is in an odd location, but makes more sense when you realize that the bottom 5 rows of grayish buttons are fixed. The top three rows of brown buttons change their function depending on the "mode", selected by the row of green buttons. I do not use the financial features enough to make any comment on those available functions.
    Although I agree with many suggestions of the reviewers below, I am giving allRPNcalc 5 stars for design and functionality. Suggestions: A reviewer below suggested an "undo" function ("last x" can be helpful but wont preserve y) - how about implementing undo by swiping finger across the number display? As a possible solution for displaying all four levels of the stack, how about pressing and holding the number display will trigger a small window that pops up (same red on black, small font like the stack/registers list) quickly showing t,z,y,x, and then disappears when your finger lets go.

meclizine50mg about allRPNCalc Calculator