.. py:function:: integral(fs) Computes the surface integral of each field in ``fs``. :param fs: input fieldset :type fs: :class:`Fieldset` :rtype: number or ndarray The result is either a **number** (for one input field) or an **ndarray** (for multiple input fields). The computations are based on the cell area (in m\ :sup:`2` units) returned by :func:`grid_cell_area`.
.. mv-minigallery:: integral