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Adam's Images

Wednesday 25 April 2012: RPN

Feeling a lot better today even if I have zero blip creativity. Unlike yesterday which was mostly dry and sunny today has been very wet and miserable.

From start of spring term in the third year* at grammar school I use to have a Casio fx-570 calculator with me at all times for maths and later all three sciences. It saw me through 'O' levels and then 'A' levels, and nearly made it through to my finals. I replaced it with the near identical fx-570CD Super-FX model for my finals. I used it a bit while doing my second degree but even as an academic I never used a calculator in anger.

Since leaving academia I've never used a physical calculator for anything. Any thing to do with money I use a spreadsheet and if I do need to do real sums, every computer I have access to (desktop, laptop, phone) comes with a calculator built-in - the Linux desktop calculators being amazingly powerful beasts.

This is not a blip of my Casio, instead it's a blip of a HP 32S II reverse Polish notation calculator. It was gift from an in-law, who also had one. I knew of them but had never seen a real one, once when we were visiting and we asked for a calculator for something and this appeared I was impressed to see it. Hence it appeared as a gift later that Christmas. It works of a stack and in effect the reverse of the way all other calculators work. It's a bit strange but it's actually more efficient and in many respects a better design.

On a regular calculator you trpe 2 + 3 = and it gives 5.

On an RPN calculator you type 2 <enter> 3 <enter> + and it gives 5.

There isn't the space here to really explain it, but it's a really elegant way of doing complex calculations, you just have to unlearn what you have been taught in school and then you'll appreciate how beautiful it is for some problems you may want to solve.

* don't know what that is in current schools


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