Error when integrating absolute value

[pinkman]

(12-09-2019 06:51 AM)parisse Wrote:  No, but ask yourself, how did you get this result? You probably cut the integral in several parts.

Yes I did. I even did twice before writing my question!

(12-09-2019 06:51 AM)parisse Wrote:  The problem here is to find the cut positions. You have to solve an equation for that, and after I had problems with more complicated inputs, I decided to solve this equation only if it was univariate. This is not the case if there is a parameter, that's why you got the warning and a wrong answer.

Ok understood, but just to be sure: if k is not a function of x, and here it is not, it is a coefficient (a constant factor), not a parameter, isn’t it? Because you had the right result 4 without the k, and this constant k is out of the abs() operand, it doesn’t interfere with the result, doesn’t it?

(12-09-2019 06:51 AM)parisse Wrote:  I have already modified the source code to solve it for this input because the dependancy in k can easily be removed, now you will get 4*k. But keep in mind that in other situations, it might be wrong, you should always read carefully the warnings and check your answer if there is a warning.

What kind of situations? A function of x? It would be revealed by the symbolic preprocessing, no? Are there any other situations?

Please note: these are real questions, not reproaches or provocation. I just want to be sure I understand the limits of CAS, because sometimes, even in presence of a warning message, I (we all?) blindly trust the machine

Et puis aussi c’est barbant de tout écrire en anglais ! Je veux juste savoir dans quels cas ce k aurait une influence sur l’intérieur de l’intégrale. Merci !