Integration of a function of multiple variables

[Fabrice Silva]

Dear Sympiers,

I have been puzzled by the results of the integration on some unknown function of several variables. For instance:

>>> import sympy as sy

>>> x, y, t = sy.symbols('x y t', real=True)

>>> vx = sy.Function('v_x')(x,y,t)

vx being thought as a scalar field in the 2D plane.

>>> sy.integrate(vx, (y))

gives the expected primitive of the field wrt the second argument y.

However

>>>sy.integrate(vx.diff(x), (y))

assumes that vx.diff(x) does not depend on y, and thus the primitive is simply y*vx.diff(x).

Did I miss some fundamental point in this trivial example ?

Best regards

Fabrice

[Aaron Meurer]

It seems this is a bug. I opened https://github.com/sympy/sympy/issues/12899.

Aaron Meurer

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[Boris Ettinger]

Created a pull request to fix the issue https://github.com/sympy/sympy/pull/12971