Setting line coordinates

Marek Nedvěd shared this question 3 years ago

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Hello,

I have a problem with setting coordinates of existing line. At the other hand, setting coordinates of points works fine.

I made arbitrary line f with Line tool. Then I set a javascript inside a button:

ggbApplet.setCoords("f", 1, 1, 1);

But nothing happens.

As I wrote, setting a coordinates of point works well by this way. Could you advice me, please?

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Comments (9)

Michael Borcherds ● 3 years ago

setCoords() is for Points - try setting the coords of A and B

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Marek Nedvěd ● 3 years ago

Are you sure? There is written something different: 505f7f45ede4f59c9c84bd6efcb3326c

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jumera ● 3 years ago

Hello

Do you really think that a line have 3 coordinates..?

https://wiki.geogebra.org/e...

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Marek Nedvěd ● 3 years ago

Yes I do, the third coordinate is the absolute term "c" in equation: ax + by + c = 0

Try it:

ggbApplet.getXcoord("some_line_name");

ggbApplet.getYcoord("some_line_name");

ggbApplet.getZcoord("some_line_name");

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mathmagic ● 3 years ago

por muy absurdo que me parecía la explicación he probado a ver qué pasaba

primero he creado una recta libre escribiendo x+2y=3 (no usando dos puntos; escribiendo)

después he deseleccionado la casilla fix (a no fijo) en las propiedades de la recta

a continuación he escrito setcoords(eq1,4,5,6) and OHH! sorpresa!!!

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jumera ● 3 years ago

it was so absurd that i didn't try..!

But it doesn't work in scripts...

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mathmagic ● 3 years ago

be sure the line is not fix

the script works

Files: foro.ggb

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jumera ● 3 years ago

ok (perhaps don't fix line is the solution for Marek)

Finally, this is difference between mathematic and computing

coordinate of line is absurd for mathematics but not for computing

(other example : f=2x is absurd for mathematics but f(x)=2x is absurd for computing !)

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Michael Borcherds ● 3 years ago

Depends how you look at it

In general, there is no difference either algebraically or logically between the homogeneous coordinates of points and lines

https://en.wikipedia.org/wi...

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