the `/`character cannot be part of a symbol's name (not acepted by the
Python interpreter). Try :
```
sage: logr = SR.symbol("logr", latex_name='L_{x/x_0}')
sage: x*logr
logr*x
sage: latex(x*logr)
L_{x/x_0} x
```
BTW (question of taste...), I'd rather use `logr = SR.symbol("logr",
latex_name=r'L_{\frac{x}{x_0}}')`...
HTH,
Le lundi 4 juillet 2022 à 23:22:53 UTC+2, Markk a écrit :
> sage: x = SR.symbol('x')
> ....: x_0 = SR.symbol('x_0')
> ....: logr = SR.symbol('L_x/x_0')
> ....: logr_ex = logr == log(x/x_0)
> ....: latex(logr_ex)
> ....: latex(logr_ex.solve(x)[0])
> L_{\mathit{x/x}_{0}} = \log\left(\frac{x}{x_{0}}\right)
> x = x_{0} e^{\frac{L_{x}}{x_{0}}}
>
> The above attempt at using a symbol with a fraction in the subscript works
> (see first latex() result) until after an operation like solve(), which
> scrambles the symbol (second latex() result).
>
> Variations of logr = SR.symbol('L_{x/x}_0') with braces also work until an
> operation such as logr_ex.solve(x) with the code above, which crash Maxima
> with the traceback excerpts:
> ---------------------------------------------------------------------------
> RuntimeError Traceback (most recent call last)
> /usr/lib/python3/dist-packages/sage/interfaces/interface.py in
> __init__(self, parent, value, is_name, name)
> 731 try:
> --> 732 self._name = parent._create(value, name=name)
> 733 except (TypeError, RuntimeError, ValueError) as x:
> ...
> RuntimeError: ECL says: THROW: The catch MACSYMA-QUIT is undefined.
>
> During handling of the above exception, another exception
> occurred:---------------------------------------------------------------------------
> RuntimeError Traceback (most recent call last)
> /usr/lib/python3/dist-packages/sage/interfaces/interface.py in
> __init__(self, parent, value, is_name, name)
> 731 try:
> --> 732 self._name = parent._create(value, name=name)
> 733 except (TypeError, RuntimeError, ValueError) as x:
> ...
> /usr/lib/python3/dist-packages/sage/interfaces/interface.py in
> __init__(self, parent, value, is_name, name)
> 732 self._name = parent._create(value, name=name)
> 733 except (TypeError, RuntimeError, ValueError) as x:
> --> 734 raise TypeError(x)
> 735
> 736 def _latex_(self):
>
> TypeError: ECL says: THROW: The catch MACSYMA-QUIT is undefined.
>
> Looks like a bug, but maybe I've overlooked the correct way to define such
> symbols.
>
>
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