Prime and Saturn calculators

[Albert Chan]

(07-06-2024 05:31 PM)dm319 Wrote:  What about problem 7? Any ideas why the HP-12c gets closer to the result but the Saturns don't?

I think it is just luck, perhaps 0 was stored in I as guess, before solving rate.

HP12C: N=10, PV=-100, PMT=10, FV=1E-10

1E-4 [I] [I] -->  5.322034956E-11, [12x] -->  6.386441947E-10
1E-8 [I] [I] --> -1.400000000E-18, [12x] --> -1.680000000E-17
0      [I] [I] -->  1.818181818E-11, [12x] -->  2.181818182E-10

HP-12c internals is still a mystery ... Why would it overshoot to negative rate?

With little compounding effect, curve is practically a straight line (col 3 = npmt slope)
Also, there is very little difference among curves NPV, NPMT, NFV. (they overlap when plotted!)

Code:

lua> n,pv,pmt,fv = 10, -100e10, 10e10, 1 -- scaled so fv=1
lua> tvm(n,0,pv,pmt,fv, true)
0                       0.1                     -550000000000.45
1.8181818181803308e-13  -2.7269853042355408e-14 -550000000000.75
1.818181818179835e-13   0                       -550000000000.75
1.818181818179835e-13
lua> _ * 1200
2.181818181815802e-10