Is RPN still relevant?

[Thomas Klemm]

(12-18-2023 01:50 PM)dm319 Wrote:  I know some numbers - 60km to get home, the car is running at around 30kwh/100km at the moment (yes I know not good!), 15% of a 64.7kwh battery left, and the app says I'm charging at 11kW. As I walked up to my office, I pulled out my phone with free42, and had a timer running for 55 mins before I got there.

If anyone can visualise that formula in their mind, and know how many preceding brackets to put into their algebraic calculator, then I salute you.

\[
\frac{\frac{30 \text{kWh}}{100 \text{km}} 60 \text{km} - \frac{15}{100} 64.7 \text{kWh}}{11 \text{kW}} \approx 0.75409 \text{h}
\]

I would enter this as:

(30/100*60-15/100*64.7)/11

Not too many parentheses, I guess.

However if I want to use a fancy Lisp like Clojure I'd use:

(/ (- (* (/ 30 100) 60) (* (/ 15 100) 64.7)) 11)
0.754090909090909

Don't be imitated by the many parentheses.
In the Replete app the results are stored in *1, *2, *3.
So you can do it a bit similar to how you would do that with RPN:

(* (/ 30 100) 60)
18

(* (/ 15 100) 64.7)
9.705

(- *2 *1)
8.295

(/ *1 11)
0.754090909090909

First I wondered how you ended up with 55 minutes because my result is only 45' 15".

But then I noticed that you wrote:

(12-18-2023 01:50 PM)dm319 Wrote:  I knew I needed a bit of a top up to get back home (…)

Thus I assume that our results agree.