## [geogebra-cas] GeoGebraCAS Update

• From: "Markus Hohenwarter" <markus@xxxxxxxxxxxx>
• To: geogebra-cas@xxxxxxxxxxxxx
• Date: Wed, 24 Sep 2008 16:28:56 -0400

```Dear CAS-friends,

Quan has made very good progress on the basic user interface of the
CAS. We can now save and load sessions in a basic notebook style
interface where you can insert/remove rows flexibly. There are a few
things that Quan will finish up until next week. Then we plan to give
you a first version to play with Yacas.

GUI:
The idea is then to continue with a substitute dialog on the user
interface side (Quan and I discussed this, very similar to Derive's
"Simplify, Subexpression substitution" dialog).

Syntax:
On the syntax side, I will then start to introduce another layer to
hide Yacas from the end-user. Right now, I am thinking of a
translation layer that is basically the current GeoGebra syntax. I.e.
the user can enter both GeoGebra expressions and Yacas expressions
where GeoGebra expressions are automatically converted into Yacas
expressions in the background. We have quite some of the logic for
this in place, what we will really need then is examples - and
probably I will need to extend GeoGebra's syntax a bit ;-)

Connection CAS <-> GeoGebra
An important question is also how we want to connect the CAS window
with the rest of GeoGebra.
a) CAS -> GeoGebra is relatively straight forward: create an object in
GeoGebra that is dynamically linked to a certain CAS row. When that
CAS row updates, the object in GeoGebra is updated (if possible) or
set to undefined (if not possible)
b) GeoGebra -> CAS might be a bit trickier, let's see how we can do
this best. We could maybe use some kind of dynamic substitution where
a CAS row declares that it uses certain values of objects in GeoGebra,
e.g
A CAS row "a x + b y = c" could be linked to sliders a, b, c in
GeoGebra. Everytime the CAS row is evaluated in the CAS window (by
pressing a certain key), it would use the current slider values of a,
b, c.

start playing with the system. I'll keep you posted.

cheers,
Markus

--
Markus Hohenwarter, PhD
Florida Center for Research in Science, Technology, Engineering, and Mathematics
Florida State University, www.fcrstem.org

GeoGebra: www.geogebra.org
IGI: www.geogebra.org/IGI

```

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• » [geogebra-cas] GeoGebraCAS Update