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Calculating Pi?
Posted: Mon Jan 16, 2006 1:52 pm
by Kale
Has anyone got a way in PB to accurately calculate Pi? Here are a few ways but not very accurate:
Code: Select all
Debug StrF(4 * (ATan(1/2) + ATan(1/3)), 10)
Debug StrF(4 * (4 * ATan(1/5) - ATan(1/239)), 10)
Debug StrF((16 * ATan(1/5)) - (4 * ATan(1/239)), 10)
Debug StrF(4 * ATan(1), 10)
Any more?
Posted: Mon Jan 16, 2006 3:07 pm
by Rings
Code: Select all
a.s=a.s+ StrF(4 * (ATan(1/2) + ATan(1/3)), 10) + Chr(13)
a.s=a.s+ StrF(4 * (4 * ATan(1/5) - ATan(1/239)), 10)+ Chr(13)
a.s=a.s+ StrF((16 * ATan(1/5)) - (4 * ATan(1/239)), 10)+ Chr(13)
a.s=a.s+ StrF(4 * ATan(1), 10) + Chr(13)
a.s=a.s+ StrD(4 * (ATan(1/2) + ATan(1/3)), 10) + Chr(13)
a.s=a.s+ StrD(4 * (4 * ATan(1/5) - ATan(1/239)), 10)+ Chr(13)
a.s=a.s+ StrD((16 * ATan(1/5)) - (4 * ATan(1/239)), 10)+ Chr(13)
a.s=a.s+ StrD(4 * ATan(1), 10) + Chr(13)
MessageRequester("Info",a.s ,0)
Posted: Mon Jan 16, 2006 3:10 pm
by MikeB
Until we get higher precision floating point with PB (hopefully in V4.0) I don't think you can do an accurate calculation, even then you won't be able to get great precision without resorting to a huge loop calculating each decimal place one by one. This is an inherent problem with a never ending (as far as we know) calculation.
Posted: Mon Jan 16, 2006 3:21 pm
by DarkDragon
Rings wrote:Code: Select all
a.s=a.s+ StrF(4 * (ATan(1/2) + ATan(1/3)), 10) + Chr(13)
a.s=a.s+ StrF(4 * (4 * ATan(1/5) - ATan(1/239)), 10)+ Chr(13)
a.s=a.s+ StrF((16 * ATan(1/5)) - (4 * ATan(1/239)), 10)+ Chr(13)
a.s=a.s+ StrF(4 * ATan(1), 10) + Chr(13)
a.s=a.s+ StrD(4 * (ATan(1/2) + ATan(1/3)), 10) + Chr(13)
a.s=a.s+ StrD(4 * (4 * ATan(1/5) - ATan(1/239)), 10)+ Chr(13)
a.s=a.s+ StrD((16 * ATan(1/5)) - (4 * ATan(1/239)), 10)+ Chr(13)
a.s=a.s+ StrD(4 * ATan(1), 10) + Chr(13)
MessageRequester("Info",a.s ,0)
Works great here: PB 3.94
should I say anything else?
Posted: Mon Jan 16, 2006 5:40 pm
by RichardL
Hi,
A bit off topic.
PI is about 3 and a bit ... good enough for gardening
PI is about 22/7... good enough for early schooling
PI is about 355/113... good to about ten decimal places.
(11 33 55 first three odd numbers with a stutter; that how I remember it.)
Stupid rhyme...
Sir I have a rhyme excelling in mystic force and magic spelling
Celestial sprites elucidate all my own striving can't relate
Twenty places, count the letters! (Assuming I can spell!)
Richard L
Posted: Mon Jan 16, 2006 5:50 pm
by Dare2
Posted: Mon Jan 16, 2006 6:31 pm
by netmaestro
One way to "calculate" pi without reinventing the wheel:
Code: Select all
ProcedureDLL.s GetPi()
#INTERNET_FLAG_RELOAD = $80000000
Bytes.l = 0
Html.s = Space(1024)
r$ ="";
hInet.l = InternetOpen_("http://3.141592653589793238462643383279502884197169399375105820974944592.com/", 1, #Null, #Null, 0)
If hInet
hURL.l = InternetOpenUrl_(hInet, "http://3.141592653589793238462643383279502884197169399375105820974944592.com/", #Null, 0, #INTERNET_FLAG_RELOAD, 0)
If hURL
If InternetReadFile_(hURL, @Html, Len(Html), @Bytes)
Html = Mid(html,FindString(Html,"3.14",1),400)
For i= 1 To Bytes
;If (Mid(Html,i,1) >= "0" And Mid(Html,i,1) <= "9") Or Mid(Html,i,1) = "."
r$ = r$ + Mid(Html,i,1)
;EndIf
Next
InternetCloseHandle_(hURL)
Else
ProcedureReturn "Failed"
EndIf
Else
ProcedureReturn "Failed"
EndIf
InternetCloseHandle_(hInet)
Else
ProcedureReturn "Failed"
EndIf
ProcedureReturn r$
EndProcedure
pi$=Getpi()
MessageRequester("400 digits of pi",pi$)
Posted: Mon Jan 16, 2006 7:22 pm
by jack
Posted: Mon Jan 16, 2006 9:10 pm
by PB
> Sir I have a rhyme excelling in mystic force and magic spelling
> Celestial sprites elucidate all my own striving can't relate
Wouldn't be any good in the USA.
Posted: Mon Jan 16, 2006 10:55 pm
by Num3
Re: Calculating Pi?
Posted: Fri Apr 14, 2006 5:10 pm
by Psychophanta
Kale wrote:Has anyone got a way in PB to accurately calculate Pi? Here are a few ways but not very accurate:
Code: Select all
Debug StrF(4 * (ATan(1/2) + ATan(1/3)), 10)
Debug StrF(4 * (4 * ATan(1/5) - ATan(1/239)), 10)
Debug StrF((16 * ATan(1/5)) - (4 * ATan(1/239)), 10)
Debug StrF(4 * ATan(1), 10)
Any more?
Posted: Fri Apr 14, 2006 5:25 pm
by va!n
Code: Select all
OwnPi.d= ATan(1)*4
Debug OwnPi.d
Debug #PI
Posted: Fri Apr 14, 2006 7:59 pm
by akj
For a method to calculate Pi to a large number of decimal places, see my PB program near the end of the forum topic:
www.purebasic.fr/english/viewtopic.php?t=8530
Posted: Sat Apr 15, 2006 1:11 am
by SFSxOI
maybe i missed something, but isn't the #PI constant in PB enough already?
Posted: Sat Apr 15, 2006 3:16 am
by va!n
@SFSxOI
maybe some ppl only want to know the math / algo behind #pi
