[MWForum]more "Intersection"
Jeff Knope
mwforum@lists.mathcats.com
Thu, 12 Aug 2004 13:27:41 -0700
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Hi Wendy,
I think you're right about the relatively rough positioning based on =
pixel color. Consider, in the math, there is actually 9-place precision =
both ways in the space of a single pixel. That's a really big number of =
discreet locations.
I added code to Daniel's so it draws the lines. The top and bottom lines =
here are Daniel's, so you can see where I put it in:
make "y4 last last last :l
ht
pu setpos list :x1 :y1
pd setpos list :x2 :y2
pu setpos list :x3 :y3
pd setpos list :x4 :y4
pu home st=20
make "d1x :x1 - :x2
I can't recall for sure, I think you have to hatch a turtle too.
--Jeff
----- Original Message -----=20
From: "Wendy Petti" <wpetti@mathcats.com>
To: <mwforum@lists.mathcats.com>
Sent: Thursday, August 12, 2004 11:42 AM
Subject: RE: [MWForum]more "Intersection"
> Following up on Jeff's comparison of Daniel's mathematical code and my
> graphical code: very interesting! Can anyone explain to me why the =
output
> would be slightly different? Is this because a line segment of =
pensize 1,
> drawn on a computer screen, is still crude enough to cause a bit of
> deviation from a pure mathematical line?
>=20
> Can we modify Daniel's code to draw the line segments, too, for those =
of us
> who like a visual representation of what we're doing?
>=20
> Or I suppose we can use mine to draw the line segments while using =
Daniel's
> to output the point of intersection...
>=20
> (And thanks, Jeff, for the TOWARD utility.)
>=20
> Wendy
>=20
>=20
> _______________________________________________
> MWForum mailing list
> MWForum@lists.mathcats.com
> http://lists.mathcats.com/mailman/listinfo/mwforum
> Attachments archived at:
> http://www.mathcats.com/mwforum/attachments.html
> To unsubscribe or for administrative questions contact=20
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>=20
>
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<DIV><FONT face=3DArial size=3D2>Hi Wendy,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>I think you're right about the =
relatively rough=20
positioning based on pixel color. Consider, in the math, there is =
actually=20
9-place precision <EM>both ways </EM>in the space of a single pixel. =
That's a=20
really big number of discreet locations.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>I added code to Daniel's so it draws =
the lines. The=20
top and bottom lines here are Daniel's, so you can see where I put it=20
in:</FONT></DIV><FONT face=3DArial size=3D2>
<DIV><BR>make "y4 last last last :l</DIV>
<DIV> </DIV>
<DIV>ht<BR>pu setpos list :x1 :y1<BR>pd setpos list :x2 :y2<BR>pu setpos =
list=20
:x3 :y3<BR>pd setpos list :x4 :y4<BR>pu home st </DIV>
<DIV> </DIV>
<DIV>make "d1x :x1 - :x2<BR></DIV>
<DIV>I can't recall for sure, I think you have to hatch a turtle =
too.</DIV>
<DIV> </DIV>
<DIV>--Jeff</DIV>
<DIV> </DIV>
<DIV> </DIV></FONT>
<DIV><FONT face=3DArial size=3D2>----- Original Message ----- </FONT>
<DIV><FONT face=3DArial size=3D2>From: "Wendy Petti" <</FONT><A=20
href=3D"mailto:wpetti@mathcats.com"><FONT face=3DArial=20
size=3D2>wpetti@mathcats.com</FONT></A><FONT face=3DArial =
size=3D2>></FONT></DIV>
<DIV><FONT face=3DArial size=3D2>To: <</FONT><A=20
href=3D"mailto:mwforum@lists.mathcats.com"><FONT face=3DArial=20
size=3D2>mwforum@lists.mathcats.com</FONT></A><FONT face=3DArial=20
size=3D2>></FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Sent: Thursday, August 12, 2004 11:42=20
AM</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Subject: RE: [MWForum]more=20
"Intersection"</FONT></DIV></DIV>
<DIV><FONT face=3DArial><BR><FONT size=3D2></FONT></FONT></DIV><FONT =
face=3DArial=20
size=3D2>> Following up on Jeff's comparison of Daniel's mathematical =
code and=20
my<BR>> graphical code: very interesting! Can anyone =
explain to=20
me why the output<BR>> would be slightly different? Is this =
because a=20
line segment of pensize 1,<BR>> drawn on a computer screen, is still =
crude=20
enough to cause a bit of<BR>> deviation from a pure mathematical=20
line?<BR>> <BR>> Can we modify Daniel's code to draw the line =
segments,=20
too, for those of us<BR>> who like a visual representation of what =
we're=20
doing?<BR>> <BR>> Or I suppose we can use mine to draw the line =
segments=20
while using Daniel's<BR>> to output the point of =
intersection...<BR>>=20
<BR>> (And thanks, Jeff, for the TOWARD utility.)<BR>> <BR>>=20
Wendy<BR>> <BR>> <BR>>=20
_______________________________________________<BR>> MWForum mailing=20
list<BR>> </FONT><A href=3D"mailto:MWForum@lists.mathcats.com"><FONT =
face=3DArial=20
size=3D2>MWForum@lists.mathcats.com</FONT></A><BR><FONT face=3DArial =
size=3D2>>=20
</FONT><A =
href=3D"http://lists.mathcats.com/mailman/listinfo/mwforum"><FONT=20
face=3DArial=20
size=3D2>http://lists.mathcats.com/mailman/listinfo/mwforum</FONT></A><BR=
><FONT=20
face=3DArial size=3D2>> Attachments archived at:<BR>> </FONT><A=20
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face=3DArial=20
size=3D2>http://www.mathcats.com/mwforum/attachments.html</FONT></A><BR><=
FONT=20
face=3DArial size=3D2>> To unsubscribe or for administrative =
questions contact=20
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href=3D"mailto:mwforum-admin@lists.mathcats.com"><FONT=20
face=3DArial =
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face=3DArial size=3D2>> <BR>> </FONT></BODY></HTML>
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