The DefineFunction command sends the given string, defn, to be executed by a Python interpreter. Typically the string defn will contain a Python function definition beginning with "def ".

This command is equivalent to calling Python:-EvalString with the output=none option.

This command always returns NULL.  A subsequent EvalString or GetVariable command must be used if you want to get a reference to the procedure that was defined.

This function is part of the Python package, so it can be used in the short form DefineFunction(..) only after executing the command with(Python). However, it can always be accessed through the long form of the command by using Python[DefineFunction](..).

$\mathrm{with}\left(\mathrm{Python}\right)\:$

$\mathrm{DefineFunction}\left(''def\; mysum(a,b):\; return\; a+b''\right)$

$\mathrm{EvalString}\left(''mysum(1,2)''\right)$

$3$

$\mathrm{MySum}≔\mathrm{GetVariable}\left(''mysum''\right)$

$\mathrm{MySum}\left(4\,5\right)$

$9$

$\mathrm{DefineFunction}\left(''def\; flatten(lst):\backslash n\backslash treturn\; sum(\; ([x]\; if\; not\; isinstance(x,\; list)\; else\; flatten(x)\backslash n\backslash tfor\; x\; in\; lst),\; []\; )''\right)\:$

$\mathrm{EvalString}\left(''flatten([[1],2,[[3],4,5]])''\right)$

$\left[1\,2\,3\,4\,5\right]$

The Python[DefineFunction] command was introduced in Maple 2018.

For more information on Maple 2018 changes, see Updates in Maple 2018.