LambertW displaying in jupyter lab

[vasarm]

When using JupyterLab and trying to raise LambertW function to some power (for example multiplying with itself) then it raises error when trying to display it. Same thing happens if I use sp.Pow() method as well.

For example sp.Pow(sp.LambertW(2), 2) causes the error as well.

In [1]: import sympy as sp

In [2]: function = sp.LambertW(2) * sp.LambertW(2)

In [3]: function

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
~\miniconda3\lib\site-packages\IPython\core\formatters.py in __call__(self, obj)
    343             method = get_real_method(obj, self.print_method)
    344             if method is not None:
--> 345                 return method()
    346             return None
    347         else:

~\miniconda3\lib\site-packages\sympy\core\_print_helpers.py in _repr_latex_(self)
     62         """
     63         from sympy.printing.latex import latex
---> 64         s = latex(self, mode='plain')
     65         return "$\\displaystyle %s$" % s

~\miniconda3\lib\site-packages\sympy\printing\printer.py in __call__(self, *args, **kwargs)
    371 
    372     def __call__(self, *args, **kwargs):
--> 373         return self.__wrapped__(*args, **kwargs)
    374 
    375     @property

~\miniconda3\lib\site-packages\sympy\printing\latex.py in latex(expr, **settings)
   2946 
   2947     """
-> 2948     return LatexPrinter(settings).doprint(expr)
   2949 
   2950 

~\miniconda3\lib\site-packages\sympy\printing\latex.py in doprint(self, expr)
    252 
    253     def doprint(self, expr):
--> 254         tex = Printer.doprint(self, expr)
    255 
    256         if self._settings['mode'] == 'plain':

~\miniconda3\lib\site-packages\sympy\printing\printer.py in doprint(self, expr)
    289     def doprint(self, expr):
    290         """Returns printer's representation for expr (as a string)"""
--> 291         return self._str(self._print(expr))
    292 
    293     def _print(self, expr, **kwargs):

~\miniconda3\lib\site-packages\sympy\printing\printer.py in _print(self, expr, **kwargs)
    327                 printmethod = '_print_' + cls.__name__
    328                 if hasattr(self, printmethod):
--> 329                     return getattr(self, printmethod)(expr, **kwargs)
    330             # Unknown object, fall back to the emptyPrinter.
    331             return self.emptyPrinter(expr)

~\miniconda3\lib\site-packages\sympy\printing\latex.py in _print_Pow(self, expr)
    649         else:
    650             if expr.base.is_Function:
--> 651                 return self._print(expr.base, exp=self._print(expr.exp))
    652             else:
    653                 tex = r"%s^{%s}"

~\miniconda3\lib\site-packages\sympy\printing\printer.py in _print(self, expr, **kwargs)
    327                 printmethod = '_print_' + cls.__name__
    328                 if hasattr(self, printmethod):
--> 329                     return getattr(self, printmethod)(expr, **kwargs)
    330             # Unknown object, fall back to the emptyPrinter.
    331             return self.emptyPrinter(expr)

TypeError: _print_LambertW() got an unexpected keyword argument 'exp'

[oscarbenjamin]

This can be fixed with something like:

diff --git a/sympy/printing/latex.py b/sympy/printing/latex.py
index debc81ca8d..5bf0cff782 100644
--- a/sympy/printing/latex.py
+++ b/sympy/printing/latex.py
@@ -2422,11 +2422,15 @@ def _print_DMF(self, p):
     def _print_Object(self, object):
         return self._print(Symbol(object.name))
 
-    def _print_LambertW(self, expr):
+    def _print_LambertW(self, expr, exp=None):
+        arg0 = self._print(expr.args[0])
+        exp = r'^{%s}' % (exp,) if exp is not None else ''
         if len(expr.args) == 1:
-            return r"W\left(%s\right)" % self._print(expr.args[0])
-        return r"W_{%s}\left(%s\right)" % \
-            (self._print(expr.args[1]), self._print(expr.args[0]))
+            result = r"W%s\left(%s\right)" % (exp, arg0)
+        else:
+            arg1 = self._print(expr.args[1])
+            result = r"W_{%s}%s\left(%s\right)" % (exp, arg0, arg1)
+        return result
 
     def _print_Morphism(self, morphism):
         domain = self._print(morphism.domain)

[Arnab1181412]

Hi Can I get to solve this problem I am a new contributor. Can you guide me for the same.

[mohajain]

This can be fixed with something like:

I have made the changes suggested by @oscarbenjamin. Is there anything else that needs to be done?

[BalasubramanyamEvani]

Hello @oscarbenjamin could you please review my PR - #21849