On Wed, Apr 3, 2019 at 2:47 PM <[email protected]> wrote:
> The simplest example:
>
> f = piecewise([[[-pi-1, -pi/2], 0], [(-pi/2,pi/2), 1], [[pi/2, pi+1], 0]])
> print(f(-pi))
>
>
I'm not sure why it isn't evaluating symbolic numbers like pi, but here's a
work-around:
sage: f = piecewise([((-pi-*1*, -pi/*2*), *0*), ((-pi/*2*,pi/*2*), *1*),
((pi/*2*, pi+*1*), *0*)])
sage: ff = *lambda* x: f(RR(x))
sage: ff(-pi)
0
sage: f(-*3.1415*)
0
which gives the traceback:
>
> TypeError Traceback (most recent call last)
> <ipython-input-49-655f6ae30ee7> in <module>()
> ----> 1 f(-pi)
>
> /Applications/SageMath-8.7.app/Contents/Resources/sage/local/lib/python2.7/site-packages/sage/symbolic/expression.pyx
> in sage.symbolic.expression._eval_on_operands.new_f
> (build/cythonized/sage/symbolic/expression.cpp:66491)()
> 12677 new_args = list(ex._unpack_operands())
> 12678 new_args.extend(args)
> > 12679 return f(ex, *new_args, **kwds)
> 12680 return new_f
> 12681
>
> /Applications/SageMath-8.7.app/Contents/Resources/sage/local/lib/python2.7/site-packages/sage/functions/piecewise.py
> in __call__(self, parameters, variable, value, **kwds)
> 472 if value is not None:
> 473 substitution[variable] = value
> --> 474 return self.subs(substitution)
> 475
> 476 def _fast_float_(self, *args):
>
> /Applications/SageMath-8.7.app/Contents/Resources/sage/local/lib/python2.7/site-packages/sage/symbolic/expression.pyx
> in sage.symbolic.expression.Expression.substitute
> (build/cythonized/sage/symbolic/expression.cpp:30025)()
> 5289
> smap.insert(make_pair((<Expression>self.coerce_in(k))._gobj,
> 5290
> (<Expression>self.coerce_in(v))._gobj))
> -> 5291 res = self._gobj.subs_map(smap, 0)
> 5292 return new_Expression_from_GEx(self._parent, res)
> 5293
>
> /Applications/SageMath-8.7.app/Contents/Resources/sage/local/lib/python2.7/site-packages/sage/functions/piecewise.py
> in _subs_(self, subs_map, options, parameters, x)
> 226 if hasattr(point, 'pyobject'):
> 227 # unwrap any numeric values
> --> 228 point = point.pyobject()
> 229 else:
> 230 raise ValueError('substituting the piecewise variable
> must result in real number')
>
> /Applications/SageMath-8.7.app/Contents/Resources/sage/local/lib/python2.7/site-packages/sage/symbolic/expression.pyx
> in sage.symbolic.expression.Expression.pyobject
> (build/cythonized/sage/symbolic/expression.cpp:6083)()
> 372
> 373 cdef class Expression(CommutativeRingElement):
> --> 374 cpdef object pyobject(self):
> 375 """
> 376 Get the underlying Python object.
>
> /Applications/SageMath-8.7.app/Contents/Resources/sage/local/lib/python2.7/site-packages/sage/symbolic/expression.pyx
> in sage.symbolic.expression.Expression.pyobject
> (build/cythonized/sage/symbolic/expression.cpp:6009)()
> 428
> 429 if not is_a_numeric(self._gobj):
> --> 430 raise TypeError("self must be a numeric expression")
> 431 return py_object_from_numeric(self._gobj)
> 432
>
> TypeError: self must be a numeric expression
> sage: f(-pi)
> ---------------------------------------------------------------------------
> TypeError Traceback (most recent call last)
> <ipython-input-50-655f6ae30ee7> in <module>()
> ----> 1 f(-pi)
>
> /Applications/SageMath-8.7.app/Contents/Resources/sage/local/lib/python2.7/site-packages/sage/symbolic/expression.pyx
> in sage.symbolic.expression._eval_on_operands.new_f
> (build/cythonized/sage/symbolic/expression.cpp:66491)()
> 12677 new_args = list(ex._unpack_operands())
> 12678 new_args.extend(args)
> > 12679 return f(ex, *new_args, **kwds)
> 12680 return new_f
> 12681
>
> /Applications/SageMath-8.7.app/Contents/Resources/sage/local/lib/python2.7/site-packages/sage/functions/piecewise.py
> in __call__(self, parameters, variable, value, **kwds)
> 472 if value is not None:
> 473 substitution[variable] = value
> --> 474 return self.subs(substitution)
> 475
> 476 def _fast_float_(self, *args):
>
> /Applications/SageMath-8.7.app/Contents/Resources/sage/local/lib/python2.7/site-packages/sage/symbolic/expression.pyx
> in sage.symbolic.expression.Expression.substitute
> (build/cythonized/sage/symbolic/expression.cpp:30025)()
> 5289
> smap.insert(make_pair((<Expression>self.coerce_in(k))._gobj,
> 5290
> (<Expression>self.coerce_in(v))._gobj))
> -> 5291 res = self._gobj.subs_map(smap, 0)
> 5292 return new_Expression_from_GEx(self._parent, res)
> 5293
>
> /Applications/SageMath-8.7.app/Contents/Resources/sage/local/lib/python2.7/site-packages/sage/functions/piecewise.py
> in _subs_(self, subs_map, options, parameters, x)
> 226 if hasattr(point, 'pyobject'):
> 227 # unwrap any numeric values
> --> 228 point = point.pyobject()
> 229 else:
> 230 raise ValueError('substituting the piecewise variable
> must result in real number')
>
> /Applications/SageMath-8.7.app/Contents/Resources/sage/local/lib/python2.7/site-packages/sage/symbolic/expression.pyx
> in sage.symbolic.expression.Expression.pyobject
> (build/cythonized/sage/symbolic/expression.cpp:6083)()
> 372
> 373 cdef class Expression(CommutativeRingElement):
> --> 374 cpdef object pyobject(self):
> 375 """
> 376 Get the underlying Python object.
>
> /Applications/SageMath-8.7.app/Contents/Resources/sage/local/lib/python2.7/site-packages/sage/symbolic/expression.pyx
> in sage.symbolic.expression.Expression.pyobject
> (build/cythonized/sage/symbolic/expression.cpp:6009)()
> 428
> 429 if not is_a_numeric(self._gobj):
> --> 430 raise TypeError("self must be a numeric expression")
> 431 return py_object_from_numeric(self._gobj)
> 432
>
> TypeError: self must be a numeric expression
>
>
>
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