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<FONT face=Arial
size=2>Robin:
<FONT face=Arial
size=2>
Can you direct me to
the portion of the cited web site where it says that 3 points are sufficient to
define a parabola? Three points would be sufficient to define a parabola if you
know the semi latus rectum (factor F below).
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size=2>
Please bear with me.
While both the circle and the parabola are conic sections their equations are
different.
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size=2>
Equation of Circle :
X**2 + Y**2 = R**2 R is the radius
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Equation of
parabola: Y**2 =
4FX F is the
semi latus rectum
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size=2>
Here is a little
exercise you can do. All you need are two pieces of paper, a
pencil, a compass, a straight edge (a ruler will do) and maybe an
eraser.
Place 3 points on a
piece of paper, they must not be on a straight line. Call them A, B, and C. Draw
the lines A-B and B-C. Bisect these 2 lines and draw the perpendicular
bisectors. the bisectors will meet at the center of the circle. Next select any
other 3 points on the circle and repeat this little exercise. These
bisectors will also meet at the center of the circle. Before the days
of electronic navigation, the basis of this method was used by
navigators near shore or in narrow channels to locate the position of
the vessel.
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size=2>
If you draw a
parabola and select two or more sets of three points on the parabola
and repeat the exercise, the bisectors will not meet at the same
place.
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size=2>
If you have any
further questions please write me privately
<FONT face=Arial
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<FONT face=Arial
size=2>Lionel
<FONT face=Arial
size=2>
<FONT face=Arial
size=2>
<FONT face=Arial
size=2>
<FONT face=Tahoma
size=2>-----Original Message-----From: Robin Hood
[mailto:robinhood@xxxxxxxx] Sent: Sunday, January 05, 2003 4:51
AMTo: Metastockusers@xxxxxxxxxxxxxxxSubject: Re:
[Metastockusers] RE:Re: Bar Count since certain date
Hi Lionel
Three points are sufficient as parabola is made by tho points equidistanced
(? in english ?) form another one.
<A
href="http://www.xahlee.org/SpecialPlaneCurves_dir/Parabola_dir/parabola.html";>http://www.xahlee.org/SpecialPlaneCurves_dir/Parabola_dir/parabola.html for
examples (by google).
Here is a chart form an Italian site which I don't name because of
netiquette (I think...). They build a parabola from three points, in effect.
It's the same effect I'd like to reproduce with Metastock... but the trouble are
the input dates (x coordinates) :-(
robin
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
----- Original Message -----
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black">From:
Lionel
Issen
To: <A
title=Metastockusers@xxxxxxxxxxxxxxx
href="mailto:Metastockusers@xxxxxxxxxxxxxxx";>Metastockusers@xxxxxxxxxxxxxxx
Sent: Saturday, January 04, 2003 4:57
PM
Subject: RE: [Metastockusers] RE:Re: Bar
Count since certain date
Three points
always define a circle. I think that you need at least 4 points to define
a parabola. When curve fitting a parabola you need more than 4 points as data
points always have some noise, they don't fall on a nice smooth
curve.
<FONT
face=Tahoma size=2>-----Original Message-----From: Robin Hood
[mailto:robinhood@xxxxxxxx] Sent: Saturday, January 04, 2003 8:25
AMTo: Metastockusers@xxxxxxxxxxxxxxxSubject: Re:
[Metastockusers] RE:Re: Bar Count since certain date
Hi Group
Thanks to Spyros for his formula.
In order to build a parabolic trend-line, I need three points (geometry
requires it). It means three x,y (date, price) coordinates.
The problem is that metastock accepts only six inputs (in oder to define
dates I need 3+3+3=9 inputs :-( ).
Is there another way to make this?
Now, the formula inputs are as follows, but I'd like to change the
numbers with dates since I don't understand very well and immediately their
sequence
x1:=Input("point 1 : x1",-100000000,100000000,0);y1:=Input("
y1",-100000000,100000000,0);x2:=Input("point 2 :
x2",-100000000,100000000,0);y2:=Input("
y2",-100000000,100000000,0);x3:=Input("Point 3:
x3",-100000000,100000000,0);y3:=Input(" y3",-100000000,100000000,0);
Thanks in advance, Robin
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
----- Original Message -----
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black">From:
SR
To: <A
title=Metastockusers@xxxxxxxxxxxxxxx
href="mailto:Metastockusers@xxxxxxxxxxxxxxx";>Metastockusers@xxxxxxxxxxxxxxx
Sent: Saturday, January 04, 2003 2:24
PM
Subject: [Metastockusers] RE:Re: Bar
Count since certain date
bruneski came up with a variation of my approach which is
corrects somefailures of my version.So I suggest trying this
one:{BarsSinceDate}d:=Input("Day",1,31,1);m:=Input("Month",1,12,1);y:=Input("Year",1920,2030,2002);mydate:=
10000*y + 100*m + d;date:= 10000*Year() + 100*Month() +
DayOfMonth();count:=BarsSince(mydate<=date); {use '<' if first day
is not to becounted}count:=count +
Cum(If(count=0,1,0));countTo unsubscribe from
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