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dm319 · 06-16-2024, 11:55 PM

Fascinating discussion! Must confess I don't understand everything (understatement), but I think Rob you are saying that the 'correct' solve for i may not be a precise number given the impreciseness of representing the other values (PV/FV etc) using limited precision?

So what I'm about to say is going to sound like I'm ignoring all that...

I'm blaming bxparks for sending me on a rabbit hole of trying to programmatically measure accuracy of these solvers. It has involved all sorts of trouble, including use of AWK (did you know it has arbitrary precision BTW?), discovering that tidyverse isn't compatible with the gnu multiple precision library, but finding that data.table is. And also learning a bit about what 'accuracy' is.

Anyway, I think I have finally arrived at some results which look somewhat correct. I have taken absolute accuracy for interest rate and relative accuracy for all other values.

abs accuracy = -log10(abs(ref - result))
rel accuracy = -log10(abs(ref - result) / abs(ref))

I've given a +3 bonus for precise result (Inf accuracy) and a -3 penalty for failing to come to a solution. I think these results are truer than my 'eyeball, and round in my head the number of digits of precision', which was prone to errors that I kept finding as I added more data.

Code:

|calculator                 |    1|   1b|    2|    3|    4|   5A|   5B|   6A|   6B|    7|  8|    9|   10|   11|   12| acc_mean|

|:--------------------------|----:|----:|----:|----:|----:|----:|----:|----:|----:|----:|--:|----:|----:|----:|----:|--------:|

|R Rmpfr                    | 16.8| 36.1| 36.3| 36.7|   NA| 35.3| 35.0| 35.5| 35.3| 35.5| 42| 36.4| 36.4|   NA|   NA|     34.8|

|NSTK TVM V8                | 16.8| 33.1| 33.2| 32.7| 21.4| 32.3| 32.0| 32.5| 32.3| 32.5| 39| 33.4| 33.4| 28.4| 36.1|     31.3|

|C47 eadc4507f              | 16.8| 32.7| 33.3| 30.6| 18.4| 32.3| 35.0| 32.5| 32.3| 25.0| 37| 31.1| 30.9| 27.7| 33.1|     29.9|

|Plus42 1.1.9               | 16.8| 33.1| 32.4| 33.7| 21.4| 31.8|   NA|   NA| 32.3| 31.4| 36| 29.8| 30.3| 31.0| 23.7|     29.5|

|NSTK TVM V5                | 16.8| 31.0| 33.1| 25.2|  9.3| 31.3| 31.7| 31.4| 32.3| 19.8| 32| 33.4| 25.7|   NA|   NA|     27.2|

|NSTK TVM V6                |  1.3|  3.0| 33.1| 25.2| 21.4| 32.3| 32.0| 32.5| 32.3| 32.5| 39| 29.8| 30.3|   NA|   NA|     26.5|

|TI-83 Plus                 | 13.8| 12.9| 12.8| 13.3| 21.4| 11.7|   NA|   NA| 11.9| 20.4| 19|  5.6|  5.2| 10.8|  1.0|     12.3|

|RPN83P v0.9.0              | 13.1| 12.9| 13.4| 13.4| 21.4| 12.0| 11.3| 11.4| 11.5| 11.4| 13|  5.6|  5.2| 11.7|  1.9|     11.3|

|Casio FC-200               |  9.6|  9.3|   NA| 10.6| 12.1|  5.7|  8.3|  5.4|  5.4| 19.7| 12|   NA|   NA|   NA|   NA|      9.8|

|HP-17BII                   | 12.4| 10.7| 11.7| 12.2| 11.1|  5.7|  8.3|  5.4|  5.4| 11.7| 12|   NA|   NA|   NA|   NA|      9.7|

|HP-17B                     | 12.4| 10.7| 11.7| 12.2| 11.1|  5.7|  8.3|  5.4|  5.4| 11.9| 12|  6.6|  6.2|   NA|   NA|      9.2|

|TI BA II Plus Professional |  9.6|  9.5|  8.7| 10.6| 13.2|  8.7|   NA|   NA|  8.4| 16.7| 12|  4.6|  4.5|  9.5|  3.3|      9.2|

|HP-12cp                    | 12.4| 11.0| 11.7| 12.2| 11.1|  5.7|  8.3|  5.4|  5.4| 21.4| 12|  3.2|  3.5| 11.0|  2.8|      9.2|

|HP-20b                     | 12.4| 10.7| 11.7| 12.2| 11.1|  5.7|  8.3|  5.4|  5.4| 11.7| 12|  6.6|  6.2| 10.9|  2.8|      8.9|

|HP-30b                     | 12.4| 10.7| 11.7| 12.2| 11.1|  5.7|  8.3|  5.4|  5.4| 11.7| 12|  6.6|  6.2| 10.9|  2.8|      8.9|

|Sharp PC-1403H HPF 188177  |  9.6|  8.5|  8.8| 10.6| 21.4|  8.7|   NA|  5.4|  5.4|  9.7| 15|  1.7|  1.2|  6.1|  1.0|      8.1|

|HP-12c comma               |  9.6|  9.5| 11.7|  7.2|  6.0|  8.7|   NA|  8.4|   NA|  6.7| 12|  3.2|  3.2|   NA|   NA|      7.8|

|HP-92                      |  9.6|  8.5|  8.8| 10.6| 21.4|  5.7|  8.3|  5.4|  5.4|  9.7| 12|  1.7|  1.6|  4.3|  1.2|      7.6|

|Sharp EL-735               |  9.6|  8.3|  8.7|  3.5| 21.4|  5.7|  8.3|  5.4|  5.4|  9.7|  9| 12.3|  2.7|  1.2|  1.6|      7.5|

|HP-12c                     |  9.6|  8.6|  8.8| 10.6|  9.1|  5.7|  8.3|  5.4|  5.4| 19.7| 12|  1.7|  1.6|  4.6|  1.0|      7.5|

|HP-37E                     |  9.6|  8.5|  8.8| 10.6|  9.0|  5.7|  8.3|  5.4|  5.4|  9.7| 12|  1.7|  1.6|  6.0|  1.0|      6.9|

|HP-38E                     |  9.6|  8.5|  8.8| 10.6|  9.0|  5.7|  8.3|  5.4|  5.4|  9.7| 12|  1.7|  1.6|  6.0|  1.0|      6.9|

|HP-27                      |  9.6|  9.5|  8.8|  9.0|  9.0|  5.7|  8.3|  5.4|  5.4|  6.7|  6|  1.5| -1.8|  4.3| -2.0|      5.7|

|HP-22                      |  9.6|  8.6|  8.8|  9.0|  9.0|  5.7|  8.3|  5.4|  5.4|  6.7|  6|  1.7| -1.8|  4.7| -2.0|      5.7|

|Sharp PC-1421              |  9.6|  8.2|  8.7|  3.5|  6.0|  8.7|   NA|  8.4|   NA|  9.7|  9|  1.7|  1.6| -9.0|  1.6|      5.2|

|HP-70                      |  9.3|  6.6|  8.8|  1.2|  9.0|  5.7|  8.3|  5.4|  5.4|  6.7|  6|  1.7| -1.8| -1.1| -2.0|      4.6|

|HP-80                      |  9.6|  5.1|  9.4|  1.2|  6.0|  5.7|  8.3|  5.4|  5.4|  6.7|  6|  1.3| -1.8| -1.0| -2.0|      4.3|

I do have pretty graphs but they will have to wait until I'm happy these results are robust.

More importantly: does anyone have an HP-41 with financial pack? Also I'm missing the Prime. Wouldn't mind a bit more Casio too while I'm at it.