Créer une intégrale à plusieurs variables génère des constante d'intégration pour rigoler

Falmir shared this problem 3 years ago
Not a Problem

Si on tape une intégrale, il existe un certain nombre de situations ou des constantes d'intégrations apparaissent ad nauséam pendant la frappe :


Si on a une fonction de plusieurs variable:


  1. C(t, x) = intégrale(cos(x)*cos(t-x), x)

et qu'on modifie la formule après qu'elle soit complète (par exemple on ajoute des blancs)


Ou bien avec une intégrale simple:


  1. S(t) = intégrale(cos(t))

si pour le changer le nom de la fonction, on commence par le supprimer... (juste le nom, pas les parenthèses) - [POUF], y-a deux nouvelles constantes qui apparaissent par magie...

Comments (6)

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Confirmed in v.6 Classic online and Graph Calc

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Weird behavior.

If I copy and paste your examples, I get exactly what you described when renaming the functions or just modifying their definition. In this case I get multiple constants. It looks like GeoGebra remembers that the first constant it created was related to the original input of the function. Any time you modify the function, it creates another constant, that is referred to the new definition of the function. This may seem weird, but it's legit.


What I don't understand is why, both in ggb Classic 6 and Graph Calc, if I just type in something like Integral(x^2+2x+1) I get the related integral function without an arbitrary constant.

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Probably because they already had problems with such things and made a bad patch on it ;-)


I forgot to mention that I found this, one year ago. It's most probably related...

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If you read what I wrote, the fact of multiple costants looks legit, because each time you modify a function, it is a new function, so the constant related to the old one remains there.

I understand that it doesn't look intuitive. But the software is not a person. And we are able to extend (usually) our reasoning even if the procedures we have learned are not applied as expected.

This is what differs us from software I guess ;)

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About the bad patch, it's not the best of polite comments :) but I understand you, since we both are not English native speakers.

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Well, it's not about being intuitive. I believe it causes really problematic consequences : Not only is it filling your left panel with garbage you'll need to delete manually afterwards; but also, since those constants are displayed by their values - zero by default means not displayed at all, in fact - in the left pane => there is no way to identify which constant is used in which primitive () - which is especially annoying if you have many primitives (I have filled bug another report about that).

By the way, I don't think it should happen for every character you type because of the preview nor even when you're just inserting whitespaces, because in this case, it IS the same function.

About the bad patch, I didn't mean any harm : I love this software and it's only the patch which was probably bad. We all have times when we must find a quick fix to a problem and were not able to review things thoroughly enough smile

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