.. index:: UserFunctionMD
A UserFunctionMD is the multi-dimensional equivalent of :ref:`UserFunction <func-UserFunction>`. It is defined by a string formula. The formula is assigned by setting string attribute Formula:
`` "name=UserFunctionMD,Formula=a + y + (b + 0.1*y) * x, a=0, b=2"``
The fitting parameters become defined only after the Formula attribute is set that is why Formula must go first in UserFunctionMD definition.
.. attributes::
.. properties::
.. categories::
.. sourcelink::