Subject:
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Re: Hold on primitives by pneaster
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Newsgroups:
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lugnet.cad
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Date:
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Wed, 11 Jun 2003 18:04:13 GMT
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Viewed:
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485 times
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In lugnet.cad, Bernd Broich wrote:
> Niels Karsdorp <nkp.nkp@hetnet.nl> schrieb im Newsbeitrag
> news:HGBE24.1IJM@lugnet.com...
> > Sorry, i don't know who pneaster is, but he did put a hold
> > on some primitives for differences in values. • It's me...
> >
> > I would like to know how these values are to be calculated
> > (and who calculated the correct values, me or pneaster)
I have had a few emails with the Parts Tracker admin's lately to discuss the
creation of primitives. I was INCORRECTLY using the rounding method that rounded
only the final results. Like this; round( r* sin( Angle ), 4).
The agreed upon method is r* round( sin( Angle ),4).
I am still not fully sure about another final rounding.
in example; round( r* round( sin( Angle ), 4), 4)
This is the current method I am using.
> >
> > I calculated the first value with the formula:
> > 7 * SIN( PI / 8), where PI = 3.14159265358979
> > (Excel can't handle more digits for PI)
> > Which results into 2.67878402655563, rounded to 2,6788
> >
> > If I use Windows Calculator with
> > PI=3.1415926535897932384626433832795
> > the result is
> > 2.6787840265556284020992198882128
> > rounded as 2.6788
> >
> > How does pneaster get the result 2.6789 ????
Niels,
ok, your "8" comes from 180/22.5 = 8
(this is to get from degrees to radians)
Angle = 22.5 = 360/16 (This is 1/16 of a normal primitive segment)
and so... 7 * round( sin( PI / 180 * 22.5),4) = 2.6789
sin (PI/180*22.5)=0.382683432
round(0.382683432, 4)= 0.3827
7* 0.3827 = 2.6789
> I've the same problem on my parts.
> The parts is (maybe) checked by inlining the edge.dat and then
> multiplied this with the radius (for example in MLCAD).
Yes, This is the desired end result. For making resized primitives match up to
large sized primitives.
>
> This comes to the result of the review. The points of the edge
> with radius 1 is approximate by 4 digits, but this leads to an
> error when you multiply this with R to get a new circle with
> this radius.
I'm not following you here. Give me an example.
>
> So the question is how to calculate new (round) primitives?
>
> a) With the correct points new calculated as you write above?
> or b) With the R=1 points multiplied with the new Radius?
>
> CU Bernd
Here is a reason for doing this this way.
How many times have you actually calculated the true points and made a new
primitve Only to find out that when another rescaled primitive will not match up
and render correctly. This is the reason why the method I have shown above must
be used.
Anyone else care to comment too?
Paul Easter
http://www.geocities.com/pneaster/lcad_util.htm
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Message has 3 Replies:
 | | Re: Hold on primitives by pneaster
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| Paul Easter <pneaster@knoxy.nospm.net> schrieb im Newsbeitrag news:HGBwv1.22HB@lugnet.com... (...) For example sin(22.5°)= 0.3827 for R=1 (in edge.dat) 15*sin(22.5°)= 5.7403 for correct point 15* (0.3827) = 5.7405 for stretching the edge.dat A (...) (21 years ago, 11-Jun-03, to lugnet.cad)
| | | Re: Hold on primitives by pneaster
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| (...) Thanx for the explanation, it's clear to me now. I'll update my primitive generator and reupload the primitives I have put on the PT Niels (21 years ago, 11-Jun-03, to lugnet.cad)
| | | Re: Hold on primitives by pneaster
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| (...) I assume that this apply also to parts? Or not, because parts (partsize) won't be multiplicated as is with primitives. I created the 9V curve 2867.dat with the 'incorrectly' rounding method witch is pending in the parts tracker for (...) (21 years ago, 13-Jun-03, to lugnet.cad)
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Message is in Reply To:
| | Re: Hold on primitives by pneaster
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| Niels Karsdorp <nkp.nkp@hetnet.nl> schrieb im Newsbeitrag news:HGBE24.1IJM@lugnet.com... (...) I've the same problem on my parts. The parts is (maybe) checked by inlining the edge.dat and then multiplied this with the radius (for example in MLCAD). (...) (21 years ago, 11-Jun-03, to lugnet.cad)
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