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HP Forum Archive 16

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Super accurate Free42
Message #1 Posted by Tommi on 3 Sept 2006, 3:56 a.m.

I tried my old TVM equation in Thomas Okken's Free42 (decimal version) and was surprised it's now more accurate than my real HP42S.

Example 1:

n=63
i=0.00000161
PV=0
PMT=-1,000,000
END Mode (set B/E=0 in Solver)

Solving for FV:
HP 42S: 63,000,031.4434
Free42: 63,000,031.4433

(correct is 63,000,031.4433)

Example 2:

n=31536000
i=10/n
PV=0
PMT=-0.01
END Mode

Solving for FV:
HP 42S: 331,667.006689
Free42: 331,667.006691

(correct is 331,667.006691)

The TVM Solver can be found here: TVM Solver for HP42S

      
Re: Super accurate Free42
Message #2 Posted by Paul Dale on 3 Sept 2006, 7:07 a.m.,
in response to message #1 by Tommi

Free42 carries 25 digits in its reals so it would be disappointing to not gain some accuracy.

- Pauli

      
Re: Super accurate Free42
Message #3 Posted by Miguel Toro on 3 Sept 2006, 9:51 p.m.,
in response to message #1 by Tommi

Hi Tommi,

I am new here and I wanted to thank you for this excellent version of the TVM. This is the one I will always use from now on. I made a modest contribution to the program, just because I do not have enough memory left in my beloved 42s. Here it is :

00 {78-Byte Prgm }
01 LBL "TVM"
02 MVAR "N"
03 MVAR "I%"
04 MVAR "PV"
05 MVAR "PMT"
06 MVAR "FV"
07 MVAR "B/E"
08 1
09 RCL "I%"
10 %
11 ENTER
12 ENTER
13 ENTER
14 LN1+X
15 RCL* "N"
16 E^X-1
17 RCL* "PMT"
18 RCL ST T
19 1/X
20 RCL+ "B/E"
21 *
22 RCL "PV"
23 RCL ST T
24 LN1+X
25 RCL* "N"
26 E^X
27 *
28 +
29 RCL+ "FV"
30 END

And this is another version if you want to take account of the payments per year (ą la 10B):

00 {88-Byte Prgm }
01 LBL "TVM"
02 MVAR "N"
03 MVAR "I%"
04 MVAR "PV"
05 MVAR "PMT"
06 MVAR "FV"
07 MVAR "P/Y"
08 MVAR "B/E"
09 1
10 RCL "I%"
11 %
12 RCL÷ "P/Y"
13 ENTER
14 ENTER
15 ENTER
16 LN1+X
17 RCL* "N"
18 E^X-1
19 RCL* "PMT"
20 RCL ST T
21 1/X
22 RCL+ "B/E"
23 *
24 RCL "PV"
25 RCL ST T
26 LN1+X
27 RCL* "N"
28 E^X
29 *
30 +
31 RCL+ "FV"
32 END

Please try it and tell me if there are "bugs".

Miguel

Edited: 3 Sept 2006, 10:34 p.m.

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