For me, Opalcalc sits nicely between the input complexity of the calculator (infix or postfix? Do I start with a number and apply a trig function to it, or start with the function as if I were writing the formula on paper? How do I get at the stats functions again?) and the big iron of the fullblown spreadsheet
Completely agree. After checking it out further, I have to say this makes a nice complement to CalcTape which I will continue using for it's sleek interface. OpalCalc makes it a bit hard to see your caption/ comments sitting at the results to which they belong.
But I am very impressed by its features. Not that I am much of a math guy. But the date-time functions alone are amazing. Easy to create time sheets. He provides a nice Workday example sheet (example #5). And just recently I discovered the smart handling of currency conversion. On the first conversion it will get ALL rates and save them in currencies.txt to have them as up-to-date as possible when you're offline.
Celsius to Fahrenheit, Least Common Mulitiple (to check up on kids' homework), custom units .... I am glad this calculator came up in this thread.