Back in the day, the second calculator I owned was a Commodore SR 4190R, a fun little beast. Once I’d found a replacement for the one I had (it’d got lost at some point) and I’d found an example of its more “experienced” brother, the SR 9190R, I decided to try and get copies of all the similarly-bodied calculators that Commodore had made back in the 70s, maybe half a dozen or so. It didn’t take too long, but there was one of that type that just eluded me, the SR4921. Until earlier this month, that is… […]
READ MOREOnce upon a time (all right, it was in May 2010), I wrote an article for PCPlus about generating all possible arithmetic operations with the standard four operators. You can read the article here. After I’d written it, I wrote a blog post about how easy it was to convert the RPN form (Reverse Polish Notation) of the expressions I was generating into the standard algebraic or infix form. You can read that post here. (Note that this post will make more sense if you read these two articles first to get some background.) […]
READ MOREYesterday afternoon I finished my latest PCPlus article on generating all possible arithmetic expressions with four operators. The article explored several algorithms, such as evaluating all full binary trees with a certain number of internal nodes (mine was four), evaluating an expression tree, and the like, and for the sidebar I slipped in a quick bit about RPN (Reverse Polish Notation) and how succinct it is for describing arithmetic expressions (there’s no operator precedence or parentheses to worry about). Equally important is the absolute ease with which you can evaluate an RPN expression compared to an algebraic one (that is, an expression using the standard infix notation). […]
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