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scale x and y axis using pixels
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Hi all:
Sometimes we have a picture of a graph (created with other software) and want to show that a certain mathematical model fits it. For this, it is necessary that we have a tool that measures the distance between two points in pixels and that Geogebra can scale x and y axis also in pixels.
With that implemented (witch I think is very easy), a new way of working with models with kids will be very interesting...
Files:
scale_in_pixels...
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Hi,
it's easier to scale the image  if the graph goes from x0 to x1 and from y0 to y1, in its properties change corner 1 to (x0,y0) and corner2 to (x1,y0).
I have another suggestion to that.
What about being able to "zoom 100%". That would mean that one distance unit in Geogebra also represent a pixel on the screen?
You can do the "zoom 100%" thing via ZoomOut[x(Corner[5])/x(Corner[3]Corner[1])].
Hi kondr:
lets see if you understand the main idea: here is a graph token from another software
Now I want you to put the coordinate axes scaled to those in the picture (to construct a model that fits it). Please show me how to do it with your idea
https://ggbm.at/547279
Well, my solution is probably not that elegant, but it works (see attached).
https://ggbm.at/547281
Hi kondr:
I purpose this solution:
https://ggbm.at/547283
Hi Kondr:
well, in fact your solution is not that ellegant but that is not the reason for my insistence in my solution. The creation of a tool that measures the distance (of two points) in pixels seems to me very natural for applications of this kind (with the possibility to give x and y axis distance in pixels also, obviously): it don't deform the image and the pupils will understand the notion of scale and why it is used; so, the "solution" proposed by me in the last post seems didatically very interesting.
Sorry but I can't understand the solution proposed by Grobe.
I didn't say that this feature request will be completely turned down (I wouldn't dare, that's something Mike or Markus must decide), I just wanted to show you that the gain of such feature is not big, because you can achieve the same (or similar) results without such tool.
The activity you describe is certainly interesting and it would be nice if we could find a way how to make the axis mapping easier. But it should be done so that GeoGebra doesn't loose anything from its simplicity (e.g. by generalising existing commands)  new switches / buttons / tools make it harder to use for beginners.
after xmas I came back
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