BUG: Si(pi).n() throws error in sage 9.2-2

[David Minnix]

Hi there,

I am using sagemath 9.2-2 installed with apt on PopOs 21.04. When I try to evaluate `Si(pi).n()` I get the following error:

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TypeError Traceback (most recent call last) /usr/lib/python3/dist-packages/sage/symbolic/expression.pyx in sage.symbolic.expression.Expression.numerical_approx (build/cythonized/sage/symbolic/expression.cpp:35783)() 6069 try: -> 6070 x = x._convert(kwds) 6071 except TypeError: # numerical approximation for real number failed /usr/lib/python3/dist-packages/sage/symbolic/expression.pyx in sage.symbolic.expression.Expression._convert (build/cythonized/sage/symbolic/expression.cpp:10297)() 1464 """ -> 1465 cdef GEx res = self._gobj.evalf(0, kwds) 1466 return new_Expression_from_GEx(self._parent, res) /usr/lib/python3/dist-packages/sage/functions/exp_integral.py in _evalf_(self, z, parent, algorithm) 868 import mpmath --> 869 return mpmath_utils_call(mpmath.si, z, parent=parent) 870 /usr/lib/python3/dist-packages/sage/libs/mpmath/utils.pyx in sage.libs.mpmath.utils.call (build/cythonized/sage/libs/mpmath/utils.c:7121)() 438 mp.prec = orig --> 439 y = mpmath_to_sage(y, prec) 440 if parent is None: /usr/lib/python3/dist-packages/sage/libs/mpmath/utils.pyx in sage.libs.mpmath.utils.mpmath_to_sage (build/cythonized/sage/libs/mpmath/utils.c:5511)() 271 y = RealField(prec)() --> 272 mpfr_from_mpfval(y.value, x._mpf_) 273 return y /usr/lib/python3/dist-packages/sage/libs/mpmath/utils.pyx in sage.libs.mpmath.utils.mpfr_from_mpfval (build/cythonized/sage/libs/mpmath/utils.c:4695)() 166 cdef long bc --> 167 sign, man, exp, bc = x 168 if man: TypeError: Cannot convert mpz to sage.rings.integer.Integer During handling of the above exception, another exception occurred: TypeError Traceback (most recent call last) <ipython-input-15-6561919e4fcc> in <module> ----> 1 Si(pi).n() /usr/lib/python3/dist-packages/sage/structure/element.pyx in sage.structure.element.Element.n (build/cythonized/sage/structure/element.c:8382)() 883 0.666666666666667 884 """ --> 885 return self.numerical_approx(prec, digits, algorithm) 886 887 def _mpmath_(self, prec=53, rounding=None): /usr/lib/python3/dist-packages/sage/symbolic/expression.pyx in sage.symbolic.expression.Expression.numerical_approx (build/cythonized/sage/symbolic/expression.cpp:35856)() 6072 pass # try again with complex 6073 kwds['parent'] = R.complex_field() -> 6074 x = x._convert(kwds) 6075 6076 # we have to consider constants as well, since infinity is a constant /usr/lib/python3/dist-packages/sage/symbolic/expression.pyx in sage.symbolic.expression.Expression._convert (build/cythonized/sage/symbolic/expression.cpp:10297)() 1463 0 1464 """ -> 1465 cdef GEx res = self._gobj.evalf(0, kwds) 1466 return new_Expression_from_GEx(self._parent, res) 1467 /usr/lib/python3/dist-packages/sage/functions/exp_integral.py in _evalf_(self, z, parent, algorithm) 867 """ 868 import mpmath --> 869 return mpmath_utils_call(mpmath.si, z, parent=parent) 870 871 def _derivative_(self, z, diff_param=None): /usr/lib/python3/dist-packages/sage/libs/mpmath/utils.pyx in sage.libs.mpmath.utils.call (build/cythonized/sage/libs/mpmath/utils.c:7121)() 437 finally: 438 mp.prec = orig --> 439 y = mpmath_to_sage(y, prec) 440 if parent is None: 441 return y /usr/lib/python3/dist-packages/sage/libs/mpmath/utils.pyx in sage.libs.mpmath.utils.mpmath_to_sage (build/cythonized/sage/libs/mpmath/utils.c:5511)() 270 if hasattr(x, "_mpf_"): 271 y = RealField(prec)() --> 272 mpfr_from_mpfval(y.value, x._mpf_) 273 return y 274 elif hasattr(x, "_mpc_"): /usr/lib/python3/dist-packages/sage/libs/mpmath/utils.pyx in sage.libs.mpmath.utils.mpfr_from_mpfval (build/cythonized/sage/libs/mpmath/utils.c:4695)() 165 cdef long exp 166 cdef long bc --> 167 sign, man, exp, bc = x 168 if man: 169 mpfr_set_z(res, man.value, MPFR_RNDZ) TypeError: Cannot convert mpz to sage.rings.integer.Integer

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I believe this should be able to be approximated numerically and should return approximately 1.851937

[Antonio Rojas]

This is not a Sage problem, it's a mpmath 1.2 issue, which broke Sage detection when using distro packages. You either need to revert commit [1] or set the MPMATH_SAGE env variable.

[1] https://github.com/fredrik-johansson/mpmath/commit/84ca137f