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

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

- Pauli

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 (à 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. *