Eagle snafu,CIRCLE command

[Robert Baer]

I gave an example to show how it is done.

Then give three totally different examples none having 0,0 for
center, two of which have the same center and the third having a
circumference the same as one of the other two examples.
Restriction: No MOVEs allowed.

 

[Robert Baer]

That is one way to do it. But, I gave an example to show you how to do it.

Did not see it.

 

[Robert Baer]

On 12/3/2013 7:31 AM, John S wrote:
On 12/2/2013 9:49 PM, Robert Baer wrote:
The following commands were tried (no more, and no less):
CHANGE LAYER 121
CHANGE WIDTH 0.0005
CIRCLE (0.496 2.842) (1 0)
Note that last command is EXACTLY from the so-called help; gives
radius of 2.884957 and if i try CIRCLE (0.496 2.842)(0 0) the
result is
exactly the same.
The position of the center does have some effect on this bogus
"diameter".

It's doing exactly as it is told. The problem is that the second set of
enclosed numbers (1 0) is NOT the radius, it is a POINT on the
circumference. Notice that your circle's circumference passes through
the point x=1, y=0 in the first case and through x=0, y=0 in the second
case. Of course, it defines the same circle because one circle passes
through both points.

To follow up with an example, if you want a circle with center at
0.496,2.842 and a 1 inch radius:

* Make sure your grid is set for inches
* CIRCLE (0.496 2.842) (1.496 2.842)

NOT what the "help" sez....Syntax CIRCLE • •.. [center, circumference]

It says ...[center, CIRCUMFERENCE]. That means two sets of coordinates.
Let me try this another way...

What is the radius of a circle whose center is at (0.496 2.842) and
whose circumference passes through (1 0)? Does the same circle's
circumference just happen to pass through (0 0)?

* NO!! Impossible.

Now try CIRCLE (0.496 2.842) (1.496 2.842) and use the info button to
read the circle's radius. You will see that it is 1 inch. That's because
the circumference passes through (1.496 2.842). As you can see, the
horizontal value 1.496 is one inch greater than 0.496 and the y
coordinate has not changed.

* Something is corrupted in Eagle; whatever i attempt to draw is invisible.
I cannot take your word for that due to the massive difference
between the TWO circles described (same center but different crossings
of circumference).

 

[Lasse Langwadt Christensen]

Den torsdag den 5. december 2013 18.27.00 UTC+1 skrev Robert Baer:

Then give three totally different examples none having 0,0 for

center, two of which have the same center and the third having a

circumference the same as one of the other two examples.

Restriction: No MOVEs allowed.

do the math CIRCLE (X Y) (X+radius Y)

GRID inch 1;
CIRCLE (0 0) (1 0);
CIRCLE (1 0) (2 0);
CIRCLE (3 3) (4 3);

three two inch circles at 0,0 1,0 3,3


-Lasse

 

[John S]

Then give three totally different examples none having 0,0 for
center, two of which have the same center and the third having a
circumference the same as one of the other two examples.
Restriction: No MOVEs allowed.

Well, do you actually mean "having a circumference the same as one of
the other two examples" or do you mean having an XY POINT ON THE
CIRCUMFERENCE the same as one of the other two examples? Do you see the
difference in the two phrases? A circle's circumference is one number. A
coordinate on the circle's circumference is a pair of numbers. Lasse
gave 3 examples but the first is at 0,0. And he did not specify that it
was the RADIUS. Nevertheless it should serve as a good example.

Tell you what, give me your circle's center and desired radius and I
will give your the coordinates you need to draw it.

Thanks, Lasse.

John

 

[John S]

Then give three totally different examples none having 0,0 for
center, two of which have the same center and the third having a
circumference the same as one of the other two examples.
Restriction: No MOVEs allowed.

Elaborating on Lasse's approach, let (x,y) be the circle's center. Let R
be the circle's radius. There are an infinite number of ways to draw
your desired circle, but the 4 easiest are shown below:

(x,y) (x+R,y)
(x,y) (x-R,y)
(x,y) (x,y+R)
(x,y) (x,y-R)

These all define the same circle.

 

[John S]

Dew tell.
Draw a circle with center at x=0.496, y=2.842 and circumference
crossing x=0, y=0.
What is the radius? Hint: SQRT(0.496^2 + 2.842^2) or about 2.885.
Now draw a NEW circle with center at x=0.496, y=2.842 and
circumference crossing x=0, y=1.
What is the radius? Hint: a circle of about 1.819 radius; leave
calculation to the student.

My mistake, Robert. I should have said (0 0) and (1 0) describe the same
circle. And yet that is not exact. There is a small difference in the
diameter which I did not want to bring up at the time because I just
wanted to tell you how to do this in Eagle.

My mistake may have caused confusion for both of us. One of the problems
(which I had hoped to avoid) is that your example is so very close that,
unless you are very careful, they look identical.

Cheers,
John

 

[Robert Baer]

"none having 0,0 for center"

 

[John S]

Then give three totally different examples none having 0,0 for
center, two of which have the same center and the third having a
circumference the same as one of the other two examples.
Restriction: No MOVEs allowed.

I did. If you do not have the decency to respond, then I will never try
to help you again.

Cheers.

 

[Robert Baer]

I did. If you do not have the decency to respond, then I will never try
to help you again.

Cheers.

Help??
I gave two DIFFERENT circles, same centers, one thru 0,0 and another
thru 0,1 and you blew me off.
It takes THREE points to define a circle,so no mater how one
"interprets" the so-called help, one cannot figure how to construct a
particular "wiggle".

 

[Lasse Langwadt Christensen]

Den lørdag den 14. december 2013 05.03.48 UTC+1 skrev Robert Baer:

Help??

I gave two DIFFERENT circles, same centers, one thru 0,0 and another

thru 0,1 and you blew me off.

It takes THREE points to define a circle,so no mater how one

"interprets" the so-called help, one cannot figure how to construct a

particular "wiggle".

a circle only takes to points, one center and one on the circumference

-Lasse

 

[[email protected]]

Den lørdag den 14. december 2013 05.03.48 UTC+1 skrev Robert Baer:

a circle only takes to points, one center and one on the circumference

If the only information you have is the points, it takes three. But
yes, two, plus knowing which one is the center will also define a
circle.

 

[John S]

Help??
I gave two DIFFERENT circles, same centers, one thru 0,0 and another
thru 0,1 and you blew me off.

No, I tried to help.

It takes THREE points to define a circle,so no mater how one
"interprets" the so-called help, one cannot figure how to construct a
particular "wiggle".

I did not know that there was a "wiggle" in a circle. In Eagle it does
not take three points. Do you not understand my email which told you how
to make a circle? Do you have problems reading the group? Do you have a
comprehension problem? I will repeat my post here:

"Elaborating on Lasse's approach, let (x,y) be the circle's center. Let
R be the circle's radius. There are an infinite number of ways to draw
your desired circle, but the 4 easiest are shown below:

(x,y) (x+R,y)
(x,y) (x-R,y)
(x,y) (x,y+R)
(x,y) (x,y-R)

These all define the same circle."

I have seen that you have some arithmetic abilities. Will these
relations help? If not, please ask and I will try to explain.

John S

 

[Robert Baer]

If the only information you have is the points, it takes three. But
yes, two, plus knowing which one is the center will also define a
circle.

THANKS! That clarity does help!

 

[Robert Baer]

No, I tried to help.


I did not know that there was a "wiggle" in a circle. In Eagle it does
not take three points. Do you not understand my email which told you how
to make a circle? Do you have problems reading the group? Do you have a
comprehension problem? I will repeat my post here:

"Elaborating on Lasse's approach, let (x,y) be the circle's center. Let
R be the circle's radius. There are an infinite number of ways to draw
your desired circle, but the 4 easiest are shown below:

(x,y) (x+R,y)
(x,y) (x-R,y)
(x,y) (x,y+R)
(x,y) (x,y-R)

These all define the same circle."

I have seen that you have some arithmetic abilities. Will these
relations help? If not, please ask and I will try to explain.

John S

OK; accepted.

 

[John S]

OK; accepted.

I do not understand your response. OK what? Accepted what? Are we done
with this?