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GeoGebra Topic Question English

Algorithm for rounding to n decimal places

lewws shared this question 4 years ago

Answered

Hi,

From numerous threads, eg.

https://help.geogebra.org/topic/inaccuracy-probem-internal-15-decimals-is-not-enough

https://help.geogebra.org/topic/decimal-precision-question

we know 15 decimal places is limit of precision within Geogebra.

However can anyone assist to use some algorithm using Geogebra scripts or Javascript inside Geogebra to convert a rational number p/q to say n decimal places where n can go up to 200?

Example from external site at mathisfun :

https://www.mathsisfun.com/...

The same question

Comments (18)

chaffeur ● 4 years ago

Hi.

To do what you are looking for Geogebra should provide some devoted instrinsic functions, like the ones below related to the well known package MatLab, or its Octave clone (free of charge).

Normally MatLab works around 15-digit precision, which can be expanded to the desired one through the funnction vpa() of symbolic calculation.

Cheers

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Michael Borcherds ● 4 years ago

You can use the CASView, eg Numeric(1/7,200)

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lewws ● 4 years ago

Thanks, Michael!

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chaffeur ● 4 years ago

Fantastic!

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lewws ● 4 years ago

@chaffeur: Thanks for both your replies.

Btw, how do I transfer these values into a textbox in Graphics 1 or 2 panel?

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Simona Riva ● 4 years ago

Right click on the CAS cell number, then select Copy as Latex in the context menu, create a new Text and paste it there.

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chaffeur ● 4 years ago

I have no idea, unfortunately. What I've done above has been carried out manually through my usual editor (geany) by separating the (pi) single-row along with the vertical green marker. Cheers

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chaffeur ● 4 years ago

According to Simona Riva suggestion

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-Loco- ● 4 years ago

Dynamic Reference:

/AZrY33zcovZCAAAAAElFTkSuQmCC

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chaffeur ● 4 years ago

The problem is: how to split down one row into several lines in i.e. 72 columns? Now, Geogebra doesn't do it.

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-Loco- ● 4 years ago

I have no solution for that... as i can not extract the displayed text programmatically. For other strings there could be done something like there.

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lewws ● 4 years ago

Thanks, -Loco-and @chaffeur perhaps using list commands and a bit of hard coding thing can work (add algorithm to make this work) see attached.

Files: rational-irrati...

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lewws ● 4 years ago

Hi Simona,

Thanks for your contribution of ideas too to copy the Latex.

Am also exploring if I could use the JavaScript Geogebra commands to copy (SetValue) over...

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chaffeur ● 4 years ago

One more idea!

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lewws ● 4 years ago

Thanks again!

Geogebra used to allow for python scripts...Hope it can be incoeporated again in one way or another in the future...

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Michael Borcherds ● 4 years ago

Another way - drag the red point:

https://www.geogebra.org/m/UipIJcvQ

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lewws ● 4 years ago

Michael,

Brilliant! Something the younger students can easily see!Thanks!

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chaffeur ● 4 years ago

So fine, Noel! Thanks a lot

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