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(35S) Perimeter of ellipse (Ramanujan 2nd Approximation)
06-27-2021, 08:53 AM (This post was last modified: 06-27-2021 09:06 AM by mchris.)
Post: #1
(35S) Perimeter of ellipse (Ramanujan 2nd Approximation)
Put the two radii in X and Y stack and execute. It uses registers A and B
Code:
P001    LBL P
P002    STO B
P003    RDN
P004    STO A
P005    RCL–B
P006    x^2
P007    RCL A
P008    RCL+B
P009    x^2
P010    /
P011    3
P012    *
P013    ENTER
P014    ENTER
P015    4
P016    X<>Y
P017    –
P018    SQRT
P019    10
P020    +
P021    /
P022    1
P023    +
P024    RCL A
P025    RCL+B
P026    *
P027    π
P028    *
P029    RTN
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06-27-2021, 09:07 AM
Post: #2
RE: (35S) Perimeter of ellipse (Ramanujan 2nd Approximation)
And if we put the following code to the end we get also the distance of the focal points from the center, on stack Y
Code:
P029    RCL A
P030    X^2
P031    RCL B
P032    X^2
P033    -
P034    ABS
P035    SQRT
P036    X<>Y
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06-27-2021, 02:46 PM
Post: #3
RE: (35S) Perimeter of ellipse (Ramanujan 2nd Approximation)
Just for checking, a numerical example please
Pedro
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06-27-2021, 08:15 PM
Post: #4
RE: (35S) Perimeter of ellipse (Ramanujan 2nd Approximation)
(06-27-2021 02:46 PM)PedroLeiva Wrote:  Just for checking, a numerical example please
Pedro

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06-27-2021, 09:07 PM
Post: #5
RE: (35S) Perimeter of ellipse (Ramanujan 2nd Approximation)
That´s great, Thank you
Pedro
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07-03-2021, 08:26 AM (This post was last modified: 07-03-2021 03:47 PM by J-F Garnier.)
Post: #6
RE: (35S) Perimeter of ellipse (Ramanujan 2nd Approximation)
Here is an alternate version, using no registers, that runs on any scientific RPN machine:

Code:
 01*LBL "P"
 02 +
 03 ENTER^
 04 ENTER^
 05 ENTER^
 06 LASTX
 07 -
 08 LASTX
 09 -
 10 X<>Y
 11 /
 12 X^2
 13 3
 14 *
 15 ENTER^
 16 ENTER^
 17 4
 18 X<>Y
 19 -
 20 SQRT
 21 10
 22 +
 23 /
 24 1
 25 +
 26 *
 27 PI
 28 *
 29 RTN

Example with y=4, x=6:
41C: 31.73087918
32S: 31.7308791784
true: 31.730879178581...

J-F
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07-03-2021, 01:55 PM
Post: #7
RE: (35S) Perimeter of ellipse (Ramanujan 2nd Approximation)
HP-11C, HP-15C:

Code:

001- LBL D
002- ENTER
003- Rv
004- x<>y
005- -
006- LASTx
007- R^
008- +
009- /
010- LASTx
011- x<>y
012- x^2
013- 3
014- *
015- ABS
016- 4
017- LASTx
018- -
019- SQRT
020- 1
021- 0
022- +
023- +
024- LASTx
025- /
026- *
027- pi
028- *
029- RTN

wp34s:

Code:

0001 LBL A
0002 [<->] XYYZ
0003 STO+ Z
0004 -
0005 RCL/ Y
0006 x[^2]
0007 # 003
0008 [times]
0009 SDR 001
0010 # 004
0011 RCL- L
0012 [sqrt]
0013 SDR 001
0014 INC X
0015 /
0016 INC X
0017 [times]
0018 # [pi]
0019 [times] 
0020 END

or


0015 +
0016 RCL/ L
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07-31-2021, 01:36 PM (This post was last modified: 07-31-2021 01:43 PM by dlidstrom.)
Post: #8
RE: (35S) Perimeter of ellipse (Ramanujan 2nd Approximation)
Here’s a SysRPL implementation using Jazz syntax:

Code:

::
 CK2NOLASTWD
 CK&DISPATCH2
 REALREAL
 ::
  0
  {{ a b h }}
  a b %- DUP %*
  a b %+ DUP %*
  %/ !h
  %PI a b %+ %*
  %1 %3 h %*
  %10 %4 %3 h %* %- %SQRT %+
  %/
  %+
  %*
 ;
;

112.5 bytes
# 9C0Eh

2xHP48GX, HP 50g, two Retrotronik ram cards, DM42
/Daniel Lidström
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