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Hi everybody,

When I was a youg student, I used a program which allowed me to calculate thousands decimals digits of PI.
It was a "stupid" game, but I was terribly impressed by this powerful calculation and watched during long, long minutes my lovely calculator.
It was on a TI 58C but I remembered that the french magazine "Sciences et Vie" gave the same program for the hp 41C.
More than 25 years after, i am looking for this program.
is someone can help me?
Thanks

Philippe

THANK YOU MIKE!!!!!!

PHILIPPE

The best PI program for the 41C I know is one published in PPC Calculator Journal V7 N5 Page 9 June 1980, 'PI TO 1,110 PLACES' by Ron Knapp.
It's based on Machin's formula:

pi=16 arctan (1/5) - 4 arctan(1/239)

Not the best method to calculate pi today, though.

Anyway, it took "only" 11 1/2 hours to compute pi to 1000 places back then. Not bad considering that a contemporaneous Apple II program did that task in 40 hours.

I've just run it on Emu42 running on my slow Pentium III: 1000 places in little less than 7 minutes.

Regards,

Gerson.

I've been running the Deep Pi program found on voidware.com on 3 different HP-41CX's, each using an AC adapter, for several month now (continuously).

Originally, the Deep Pi program calculated 6 digits of Pi at a time. But it was discovered that in at least one instance the 6th digit in a group was off by 1.

Also, I modified the Deep Pi program by inserting a RUNSW and STOPSW to time the generation of each set of 6 digits. Those 2 commands appear at steps 2 and 9, respectively.

Some results:

The first 6 digits of PI (after the 3) take about 38 minutes. The "deeper" into Pi you go the longer it takes.
Digits 619 thru 625 took over 274 hours, nearly 11.5 days.

I'd never make it without the AC adapters plugged into the battery packs. I just love seeing my calculators really work. The Deep Pi program keeps my 41s cranking!

Thanks Hugh Steers, for sharing Deep Pi on voidware.com.

Mark Taylor

Hi Philippe,

Many years ago I played with the program published in "Science et Vie", and ported it to various calculators. By now the program is in my HP41 emulator, just for fun of course... Here it is :

01 LBL "PI"
02 CLRG
03 FIX 00
04 LBL 00
05 1
06 -
07 X=0?
08 GTO 03
09 VIEW X
10 100
11 STO 00
12 CLX
13 LBL 01
14 RCL IND 00
15 FRC
16 X<>Y
17 1 E5
18 /
19 X<> Z
20 *
21 +
22 INT
23 LASTX
24 FRC
25 X<> IND 00
26 INT
27 R^
28 *
29 +
30 1 E5
31 /
32 INT
33 LASTX
34 FRC
35 1 E5
36 *
37 ST+ IND 00
38 RDN
39 DSE 00
40 GTO 01
41 1.1
42 STO 00
43 R^
44 2
45 *
46 1
47 +
48 R^
49 LBL 02
50 X<>Y
51 RCL IND 00
52 INT
53 1 E5
54 R^
55 *
56 +
57 ENTER
58 R^
59 /
60 INT
61 X<> IND 00
62 FRC
63 X<> Z
64 MOD
65 +
66 1 E5
67 *
68 ENTER
69 R^
70 /
71 INT
72 1 E5
73 /
74 ST+ IND 00
75 RDN
76 X<>Y
77 MOD
78 ISG 00
79 GTO 02
80 X<>Y
81 1
82 -
83 2
84 /
85 2 E4
86 ST+ 01
87 X<>Y
88 GTO 00
89 LBL 03
90 FIX 05
91 1.1
92 STO 00
93 CLD
94 LBL 04
95 RCL IND 00
96 STOP
97 ISG 00
98 GTO 04
99 GTO 03
100 LBL 12
101 END

I remember it was a VERY slow program, even at that time. The constants at lines 10, 41 and 91 determine the number of decimals to be computed (100 => 1,000 decimals).

Have fun !

Marc

Hi again !

I read my posting and saw that the carriage returns were mysteriously deleted, resulting in an unusable listing. Here's another one, without line numbers :

LBL "PI"
CLRG
FIX 00
LBL 00
1
-
X=0?
GTO 03
VIEW X
100
STO 00
CLX
LBL 01
RCL IND 00
FRC
X<>Y
1 E5
/
X<> Z
*
+
INT
LASTX
FRC
X<> IND 00
INT
R^
*
+
1 E5
/
INT
LASTX
FRC
1 E5
*
ST+ IND 00
RDN
DSE 00
GTO 01
1.1
STO 00
R^
2
*
1
+
R^
LBL 02
X<>Y
RCL IND 00
INT
1 E5
R^
*
+
ENTER
R^
/
INT
X<> IND 00
FRC
X<> Z
MOD
+
1 E5
*
ENTER
R^
/
INT
1 E5
/
ST+ IND 00
RDN
X<>Y
MOD
ISG 00
GTO 02
X<>Y
1
-
2
/
2 E4
ST+ 01
X<>Y
GTO 00
LBL 03
FIX 05
1.1
STO 00
CLD
LBL 04
RCL IND 00
STOP
ISG 00
GTO 04
GTO 03
END

I hope it'll be more readable. My apologies !

Marc

dear all,

I am going to take some vacation this week and i will try both program to test what is the faster one.......
I will keep you inform....
I am glad to see that I was not alone a long time ago to have fun with this crazy test.
Marc,apparently it is not the same program between the 2 Mails.
I understand that I have to use the last one which seems to be shorter

Philippe

Marc,

Disregard my previous mail.
I understand now!!!!!
My brain is not working so fast that my HP 41.......

Philippe

Marc,
I took the liberty of formatting your post. Feel free to edit yours, adding the [pre] and [\pre] codes before and after the program listing. Then delete this one, password 12345:

Hi Philippe,

Many years ago I played with the program published in "Science et Vie", and ported it to various calculators. By now the program is in my HP41 emulator, just for fun of course... Here it is :

``` 01 LBL "PI"
02 CLRG
03 FIX 00
04 LBL 00
05 1
06 -
07 X=0?
08 GTO 03
09 VIEW X
10 100
11 STO 00
12 CLX
13 LBL 01
14 RCL IND 00
15 FRC
16 X<>Y
17 1 E5
18 /
19 X<> Z
20 *
21 +
22 INT
23 LASTX
24 FRC
25 X<> IND 00
26 INT
27 R^
28 *
29 +
30 1 E5
31 /
32 INT
33 LASTX
34 FRC
35 1 E5
36 *
37 ST+ IND 00
38 RDN
39 DSE 00
40 GTO 01
41 1.1
42 STO 00
43 R^
44 2
45 *
46 1
47 +
48 R^
49 LBL 02
50 X<>Y
51 RCL IND 00
52 INT
53 1 E5
54 R^
55 *
56 +
57 ENTER
58 R^
59 /
60 INT
61 X<> IND 00
62 FRC
63 X<> Z
64 MOD
65 +
66 1 E5
67 *
68 ENTER
69 R^
70 /
71 INT
72 1 E5
73 /
74 ST+ IND 00
75 RDN
76 X<>Y
77 MOD
78 ISG 00
79 GTO 02
80 X<>Y
81 1
82 -
83 2
84 /
85 2 E4
86 ST+ 01
87 X<>Y
88 GTO 00
89 LBL 03
90 FIX 05
91 1.1
92 STO 00
93 CLD
94 LBL 04
95 RCL IND 00
96 STOP
97 ISG 00
98 GTO 04
99 GTO 03
100 LBL 12
101 END
```
I remember it was a VERY slow program, even at that time. The constants at lines 10, 41 and 91 determine the number of decimals to be computed (100 => 1,000 decimals).

Have fun !

Marc

Marc,
Ditto previous message.

Hi again !

I read my posting and saw that the carriage returns were mysteriously deleted, resulting in an unusable listing. Here's another one, without line numbers :

```LBL "PI"
CLRG
FIX 00
LBL 00
1
-
X=0?
GTO 03
VIEW X
100
STO 00
CLX
LBL 01
RCL IND 00
FRC
X<>Y
1 E5
/
X<> Z
*
+
INT
LASTX
FRC
X<> IND 00
INT
R^
*
+
1 E5
/
INT
LASTX
FRC
1 E5
*
ST+ IND 00
RDN
DSE 00
GTO 01
1.1
STO 00
R^
2
*
1
+
R^
LBL 02
X<>Y
RCL IND 00
INT
1 E5
R^
*
+
ENTER
R^
/
INT
X<> IND 00
FRC
X<> Z
MOD
+
1 E5
*
ENTER
R^
/
INT
1 E5
/
ST+ IND 00
RDN
X<>Y
MOD
ISG 00
GTO 02
X<>Y
1
-
2
/
2 E4
ST+ 01
X<>Y
GTO 00
LBL 03
FIX 05
1.1
STO 00
CLD
LBL 04
RCL IND 00
STOP
ISG 00
GTO 04
GTO 03
END
```
I hope it'll be more readable. My apologies !

Marc

;-)

you’re most welcome,

however, originally, i’d hoped the program would be interesting and find at least 1000 digits before slowing up too much, but in fact it slows up far too much way before that (eg around 200 digits).

the idea of calculating stateless digit portions of pi comes from here:

```http://numbers.computation.free.fr/Constants/Algorithms/nthdigit.html
```

and this paper here:

```http://numbers.computation.free.fr/Constants/Algorithms/nthdecimaldigit.pdf
```

i did some work to improve and adapt this approach to calculators (10 digit overflow, for example). but its still not efficient enough. i'm hoping one, day the decimal version will be improved theoretically to make this an exciting possibility.