Re: integrate bug

Coffee inspired idea:  There is no Maxima-level interface to this, but with one line of Common Lisp, we can do this:

%i1) :lisp(putprop '$f '((x) (($ff) x)) 'integral);

((X) (($FF) X))

Now we can do:

(%i1)  integrate(f(y(x))*diff(y(x),x),x);
(%o1)                              ff(y(x))


Maybe somebody would like to build a Maxima function that allows a user to declare the antiderivative of a function.

--Barton
________________________________
From: Barton Willis via Maxima-discuss <[email protected]>
Sent: Monday, April 27, 2026 4:59 AM
To: Aleksas Domarkas <[email protected]>; <[email protected]> <[email protected]>
Subject: Re: [Maxima-discuss] integrate bug

Caution: Non-NU Email



This isn't an answer to your question, but the user documentation for integrate states:

" integrate does not respect implicit dependencies established by the depends<https://urldefense.com/v3/__https://maxima.sourceforge.io/docs/manual/maxima_singlepage.html*depends__;Iw!!PvXuogZ4sRB2p-tU!CLY3z-JfJBA0okYLkEptJxh6X75cKWTLE4FUu3W-beCDzoZ2YBuigIy71MxOPVNeysWpER47Q7GRnDC34dIk0Q5Vn6wvM20Prg$> function."

One way to avoid the outativity is to make the dependence explicit:

(%i4)  integrate(f(y(x))*diff(y(x),x),x);
(%o4) integrate(f(y(x))*('diff(y(x),x,1)),x)

Notice that integrate can handle

(%i11)       integrate(cos(y(x))*diff(y(x),x),x);
(%o11)      sin(y(x))

But Maxima doesn't have a feature that allows a user to declare that F is an antiderivative of f. Maybe somebody would like to work on that.

--Barton




________________________________
From: Aleksas Domarkas <[email protected]>
Sent: Monday, April 27, 2026 1:35 AM
To: <[email protected]> <[email protected]>
Subject: [Maxima-discuss] integrate bug

Caution: Non-NU Email

 --> depends(y,x);
(%o1) [y(x)]
 --> integrate(f(y)*diff(y,x),x);
(%o39) f(y)*integrate('diff(y,x),x)
 --> constantp(f(y));
(%o2) false
Why integrate is outative for not constant ?

Aleksas

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