Pi Calculator Rev 2

This code has been declared by its author to be Public Domain code.

Pi Calculator Rev 2 by Arem (Posted 20 years ago)
Calculates Pi based on the approximate area of a circle with a given radius multiplied by 1 over that radius squared. This is simply a modification of the equation A=PiR^2. So Pi=A1/R^2. Not as limited by floats as the last one, but it would be less accurate in the long run, plus it is MUCH more time consuming, since the time to run increases exponentially with the radius used.
Open in online IDE r=Input$("Enter a value for the radius (higher is more accurate, 2000 is best): ") total=0 For x=-r To r For y=-r To r If Sqr(x^2+y^2)<r total=total+1 End If Next Next other#=1/Float(r)^2 pivalue#=other#*total Print pivalue# Delay(10000) End

Comments

Jeppe Nielsen

(Posted 20 years ago)

You can square the radius and test with that, instead of using a squareroot. Makes it much faster.
Here shows times for both methods:

Graphics3D 800,600,32,2

r=Input$("Enter a value for the radius (higher is more accurate, 2000 is best): ")

total=0

time=MilliSecs()

For x=-r To r
	For y=-r To r
		
		If Sqr(x*x+y*y)<r
			total=total+1
		End If
	Next
Next

time2=MilliSecs()-time

other#=1/Float(r)^2

pivalue#=other#*total

Print pivalue#
Print "Slow method : "+time2

total=0

time=MilliSecs()

rr=r*r

For x=-r To r
	For y=-r To r
		
		If x*x+y*y<rr
			total=total+1
		End If
	Next
Next

time2=MilliSecs()-time

other#=1/Float(r)^2

pivalue#=other#*total

Print pivalue#
Print "Fast method : "+time2

MouseWait

End

blitz monkey

(Posted 19 years ago)

uh, You know you can just put:

Print "Pi = "+Pi+"

_33

(Posted 19 years ago)

blitz monkey, some times you want to know how the value Pi gets to be calculated for your own purpose (learnin, understanding), I think this example code serves this purpose.

Please don't insult the man.

Floyd

(Posted 19 years ago)

Here's my incomprehensible contribution, in BlitzMax so we can use double precision.

' One of those whiz-bang modern algorithms for Pi.

Framework BRL.StandardIO
Import BRL.Retro

Print ; Print
Print "Eleven iterations give full double precision accuracy."
Print "Twelfth time through the mill adds nothing."
Print ; Print

s! = 0 ; m! = 1 ; d1! = 1 ; d2! = 4 ; d3! = 5 ; d4! = 6

For n = 1 To 12
	s :+ m * ( 4 / d1 - 2 / d2 - 1 / d3 - 1 / d4 )
	m :/ 16 ; d1 :+ 8 ; d2 :+ 8 ; d3 :+ 8 ; d4 :+ 8
	Print RSet(n,4) + "   " + s
Next

' Check that we got it right.

Print
Print "  Pi = " + Pi

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