My applet does not work well in the cloud, why ?

Jose Arturo Gomez Velasquez shared this problem 1 week ago

My Applets (2) of concave mirrors, when I try it on my machine, it works well and in the cloud, no. If one moves the object (dragging the point "p"), bringing it closer or moving it to the mirror, the properties must be fulfilled, but if you verify, when you place it between the focus and the mirror, the virtual image (inside the mirror), it is formed or it does not appear, and if you download the applet, you can verify that it works very well. WHY ? The same happens, when I move the object between the center and the focus and the image to the infinite leaves the screen, when returning, there is another image ???? Why ?

Comments (11)


Sorry, I don't see the difference. Please can you post screenshots showing

* what's expected

* what's wrong?


thank , my video explaining error:


Please can you sort the Algebra View by Construction Order and then find out which is the first object that is different between the 2 versions


Good morning, thank you for your interest:

I download my own concave mirror applet (any of my two concave mirror applets: example, I install it on my computer, I execute it with my current version of geogebra (when I made these applets, I had older versions of geogebra, I do not remember which one), and it works very well. When I install my applet in my computer and I open it, I check with the geogebra tool of the order of construction of the applet, and in step 41 I place the OBJECT "BLUE", which will be reflected in the concave mirror, and in step 56 , I place the respective image that is formed inverted, for that position in which I put the object in step 41, that is to say for the construction position, between the "focus F" and the center of the mirror "C", I just I do this to put the unique object and the unique image, by the geometry of the mirrors, there are no more objects or images in my applet, only construction lines, when I run the applet, moving the object closer to the mirror, the image is displaced by its construction geometry as I showed it in my video.You can download my Applet, and check it on a computer with the version of geogebra or earlier, and behave very well, forming a single image of either the real world of the mirror (right side in this concave mirror) or of the virtual side of the mirror ie left side of the mirror in black. THANK YOU FOR YOUR ATTENTION

Excuse my English!!


Good day: I do not know if I have already expressed it, but I use LINUX UBUNTU, 18.10, 18.04, in both versions of linux, it works very well. Recently installed in another Ubuntu 19.04 machine, I would fail to test if my Applet works well there. A student, download the Applet to your computer, for your exposure of mirrors and Windows (I do not know, I believe windows 10), DOES NOT WORK WELL, gives the same error as when I run it in the cloud.


Does it help if you swap

M=Intersect[c, k, 1]
R=Intersect[c, k, 2]


M=Intersect[c, k, 2]
R=Intersect[c, k, 1]


Thanks for all your interest.

I can do what you suggest, but that does not change the problem of: because in Geogebra in the cloud, the same Applet behaves in one way and in my geogebra for Linux, in another ????.

I will improve on my Applet, as soon as I can, my definition of the image that is formed in a concave mirror, using a single criterion (central ray or ray reflected by the focus), I saw, that to form the image that should appear in a concave mirror, I usually use indifferently the three "rays" or lines of the theory of curved mirrors, but maybe something happens and surely yes, because I only have to move in small objects, where a parabola coincides with a sphere or circle in this case.


1) The line of "light" that passes through the center of curvature of the sphere, always reflects on itself, that is, on the same line.

A sphere helmet is a very imperfect mirror, and is only required for "small objects" vs. "mirror curvature"

2) The lines of "light" that arrive parallel to a concave mirror and touch the object, must be reflected through its "F" focus, but it is valid for small angles, or what is the same, for a small size of the object compared to its curvature (if the mirror is spherical like the one that is always used in real life for ease of manufacture).

3) The lines or "light" that arrive through the focus "F", are reflected in reverse, that is, parallel and towards infinity (mirror right side).


I use to form the image of the "real world" of the mirror in my Applet (images of the object that are formed on the right side of the reflective surface in my Applet), the central ray that passes through the center "C" of the sphere of the one that builds the mirror.

To form the virtual image that occurs when I bring the object closer to the mirror, I use the prolongation (dotted line) of the reflected beam.

The two previous criteria are coincident in small objects and since my applet uses is the mirror "spherical" color black, and the yellow line would be a parabolic mirror (perfect). How do I use the two criteria to form my image, maybe there is a strange behavior of the applet for some case ?????

For all the above, I must take time to improve my Applet or change it and try, but my concern is more to know because the same Applet, behaves differently in GEOGEBRA in the cloud, in Geogebra in windows and in Geogebra in linux ??? ?????

The whole problem translates into how I formed the VECTOR "Image" vs VECTOR "Object", on one side or the other of the mirror: "Virtual world" (left side mirror surface) Vs "Real world" (right side mirror surface)




Gracias por todo su interes.

Yo puedo hacer lo que Usted me sugiere, pero eso no cambia el problema de: ¿ porque en Geogebra en la nube, el mismo Applet se comporta de una forma y en mi geogebra para Linux, de otra ????.

Yo voy a mejorar en mi Applet , apenas pueda, mi definicion de la imagen que se forma en un espejo concavo, usando un solo criterio (rayo central o rayo reflejado por el foco) , ya vi, que para formar la imagen que debe aparecer en un espejo concavo, normalmente me valgo indiferentemenete de los tres "rayos" o lineas de la teoria de espejos curvos, pero quizas algo pasa y de seguro que si, porque solo debo moverme en pequeños objetos, donde una parabola coincide con una esfera o circulo en este caso.


1) La linea de "luz" que pasa por el centro de curvatura de la esfera , siempre se refleja sobre si mismo , es decir, sobre la misma linea.

Un casco de esfera es un espejo muy imperfecto, y solo es preciso para "pequeños objetos" vs "curvatura espejo"

2) Las lineas de "luz" que llegan paralelas a un espejo concavo y tocan el objeto, deben reflejarse pasando por su "F" Foco, pero es valido para pequeños angulos, o lo que es lo mismo, para un tamaño pequeño del objeto comparado con su curvatura (si el espejo es esferico como el que siempre se usa en la vida real por facilidad de fabricacion).

3) Las lineas o "luz" que llegan por el foco "F", se reflejan a la inversa, es decir, paralelas y hacia el infinito (lado derecho espejo).


Yo uso para formar la imagen del "mundo real" del espejo en mi Applet (imagenes del objeto que se forman al lado derecho de la superficie reflectiva en mi Applet), el rayo central que pasa por el centro "C" de la esfera de la que se construye el espejo.

Para formar la imagen virtual que se da cuando acerco mucho el objeto al espejo, uso la prolongacion (linea punteada) del rayo reflejado.

Los dos criterios anteriores son coincidentes en pequeños objetos y ya que mi applet usa es el espejo "esferico" color negro , y la linea amarilla seria un espejo parabolico (perfecto). Como uso los dos criterios para formar mi imagen, quizas alli hay un comportamiento extraño del applet para algun caso ?????

Por todo lo anterior, debo sacar tiempo para mejorar mi Applet o cambiarlo y probar, pero mi inquietud es mas de saber porque el mismo Applet, se comporta diferente en GEOGEBRA en la nube, en Geogebra en windows y en Geogebra en linux ????????

Todo el problema se traduce en como formo el VECTOR "Image" vs VECTOR "Object", a un lado u otro del espejo: "Mundo virtual" (lado izquierdo superficie espejo ) Vs "Mundo real" (lado derecho superficie espejo)



Please make sure you are using the latest version (v536+) across all your computers


En mi linux (Debian version). In windows 5-0-536.0.

My student tried with several versions (one is the one that you refer to me 5-0-536.0.) and gives the same error when forming the image of the object in the concave mirror (spherical). Only in my linux with the referred version ( or other previous ones, it works well.



4.0.34 has the bug. Please upgrade and make my suggested changes

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