Also type(phi) gives sympy.core.function.UndefinedFunction. This is
confusing.

On 11 March 2016 at 00:31, Aaron Meurer <[email protected]> wrote:

> Since this seems to break only when the function name is "phi", this
> looks like an instance of https://github.com/sympy/sympy/issues/6938.
> But I'm not quite sure what other SymPy function is named "phi". I
> didn't find any in a quick grep.
>
> Aaron Meurer
>
> On Thu, Mar 10, 2016 at 1:54 PM, Sartaj Singh <[email protected]>
> wrote:
> > Apparently, this also does not work,
> >
> > # leosartaj at Mothership in ~/projects/sympy on git:master o [0:09:48]
> > $ isympy
> > IPython console for SymPy 1.0.1.dev (Python 2.7.11-64-bit) (ground types:
> > python)
> >
> > These commands were executed:
> >>>> from __future__ import division
> >>>> from sympy import *
> >>>> x, y, z, t = symbols('x y z t')
> >>>> k, m, n = symbols('k m n', integer=True)
> >>>> f, g, h = symbols('f g h', cls=Function)
> >>>> init_printing()
> >
> > Documentation can be found at http://docs.sympy.org/dev
> >
> > In [1]: phi = symbols('phi', cls=Function)
> >
> > In [2]: phi(5.0)
> >
> ---------------------------------------------------------------------------
> > TypeError                                 Traceback (most recent call
> last)
> > <ipython-input-2-68868fcc8946> in <module>()
> > ----> 1 phi(5.0)
> >
> > /home/leosartaj/projects/sympy/sympy/core/function.pyc in __new__(cls,
> > *args, **options)
> >     718     def __new__(cls, *args, **options):
> >     719         args = list(map(sympify, args))
> > --> 720         obj = super(AppliedUndef, cls).__new__(cls, *args,
> > **options)
> >     721         return obj
> >     722
> >
> > /home/leosartaj/projects/sympy/sympy/core/cache.pyc in wrapper(*args,
> > **kwargs)
> >      93                     retval = cfunc(*args, **kwargs)
> >      94                 except TypeError:
> > ---> 95                     retval = func(*args, **kwargs)
> >      96                 return retval
> >      97
> >
> > /home/leosartaj/projects/sympy/sympy/core/function.pyc in __new__(cls,
> > *args, **options)
> >     390         pr2 = min(cls._should_evalf(a) for a in result.args)
> >     391         if pr2 > 0:
> > --> 392             return result.evalf(mlib.libmpf.prec_to_dps(pr))
> >     393         return result
> >     394
> >
> > /home/leosartaj/projects/sympy/sympy/core/evalf.pyc in evalf(self, n,
> subs,
> > maxn, chop, strict, quad, verbose)
> >    1384             options['quad'] = quad
> >    1385         try:
> > -> 1386             result = evalf(self, prec + 4, options)
> >    1387         except NotImplementedError:
> >    1388             # Fall back to the ordinary evalf
> >
> > /home/leosartaj/projects/sympy/sympy/core/evalf.pyc in evalf(x, prec,
> > options)
> >    1282             if 'subs' in options:
> >    1283                 x = x.subs(evalf_subs(prec, options['subs']))
> > -> 1284             xe = x._eval_evalf(prec)
> >    1285             re, im = xe.as_real_imag()
> >    1286             if re.has(re_) or im.has(im_):
> >
> > /home/leosartaj/projects/sympy/sympy/core/function.pyc in
> _eval_evalf(self,
> > prec)
> >     501
> >     502         with mpmath.workprec(prec):
> > --> 503             v = func(*args)
> >     504
> >     505         return Expr._from_mpmath(v, prec)
> >
> >
> /home/leosartaj/anaconda/envs/my/lib/python2.7/site-packages/mpmath/ctx_mp_python.pyc
> > in __call__(self, prec, dps, rounding)
> >     344         if not rounding: rounding = rounding2
> >     345         if dps: prec = dps_to_prec(dps)
> > --> 346         return self.context.make_mpf(self.func(prec, rounding))
> >     347
> >     348     @property
> >
> >
> /home/leosartaj/anaconda/envs/my/lib/python2.7/site-packages/mpmath/libmp/libelefun.pyc
> > in f(prec, rnd)
> >     114     def f(prec, rnd=round_fast):
> >     115         wp = prec + 20
> > --> 116         v = fixed(wp)
> >     117         if rnd in (round_up, round_ceiling):
> >     118             v += 1
> >
> >
> /home/leosartaj/anaconda/envs/my/lib/python2.7/site-packages/mpmath/libmp/libelefun.pyc
> > in g(prec, **kwargs)
> >      95         memo_prec = f.memo_prec
> >      96         if prec <= memo_prec:
> > ---> 97             return f.memo_val >> (memo_prec-prec)
> >      98         newprec = int(prec*1.05+10)
> >      99         f.memo_val = f(newprec, **kwargs)
> >
> > TypeError: unsupported operand type(s) for >>: 'long' and 'mpf'
> >
> >
> > This does work though,
> >
> >>>> phi(5)
> > φ(5)
> >
> > However,
> >
> >>>> p = symbols('p', cls=Function)
> >>>>  p(5.0)
> > p(5.0)
> >
> >>>> p(t).xreplace({t: 5.0})
> > p(5.0) # works without any problems
> >
> >
> > By My understanding, is symbols with cls=Function arg not expected to
> make
> > an undefined function?
> >
> >
> > On Friday, 11 March 2016 00:03:38 UTC+5:30, Jason Moore wrote:
> >>
> >> I don't understand this behavior:
> >>
> >> Python 3.5.1 |Continuum Analytics, Inc.| (default, Dec  7 2015,
> 11:16:01)
> >> Type "copyright", "credits" or "license" for more information.
> >>
> >> IPython 4.1.2 -- An enhanced Interactive Python.
> >> ?         -> Introduction and overview of IPython's features.
> >> %quickref -> Quick reference.
> >> help      -> Python's own help system.
> >> object?   -> Details about 'object', use 'object??' for extra details.
> >>
> >> In [1]: from sympy import *
> >>
> >> In [2]: phi = symbols('phi', cls=Function)
> >>
> >> In [3]: t = symbols('t')
> >>
> >> In [4]: phi(t).xreplace({t: 0})
> >> Out[4]: phi(0)
> >>
> >> In [5]: phi(t).xreplace({t: 0.0})
> >> Out[5]: 1.61803398874989
> >>
> >> In [6]: phi(t).xreplace({t: 5.0})
> >>
> >>
> ---------------------------------------------------------------------------
> >> KeyError                                  Traceback (most recent call
> >> last)
> >>
> >>
> /home/moorepants/miniconda3/lib/python3.5/site-packages/sympy/core/evalf.py
> >> in evalf(x, prec, options)
> >>    1209     try:
> >> -> 1210         rf = evalf_table[x.func]
> >>    1211         r = rf(x, prec, options)
> >>
> >> KeyError: phi
> >>
> >> During handling of the above exception, another exception occurred:
> >>
> >> TypeError                                 Traceback (most recent call
> >> last)
> >> <ipython-input-6-ec5c48b4cb2f> in <module>()
> >> ----> 1 phi(t).xreplace({t: 5.0})
> >>
> >>
> >>
> /home/moorepants/miniconda3/lib/python3.5/site-packages/sympy/core/basic.py
> >> in xreplace(self, rule)
> >>    1086             args = tuple(args)
> >>    1087             if not _aresame(args, self.args):
> >> -> 1088                 return self.func(*args)
> >>    1089         return self
> >>    1090
> >>
> >>
> >>
> /home/moorepants/miniconda3/lib/python3.5/site-packages/sympy/core/function.py
> >> in __new__(cls, *args, **options)
> >>     683     def __new__(cls, *args, **options):
> >>     684         args = list(map(sympify, args))
> >> --> 685         obj = super(AppliedUndef, cls).__new__(cls, *args,
> >> **options)
> >>     686         return obj
> >>     687
> >>
> >>
> >>
> /home/moorepants/miniconda3/lib/python3.5/site-packages/sympy/core/function.py
> >> in __new__(cls, *args, **options)
> >>     380         pr2 = min(cls._should_evalf(a) for a in result.args)
> >>     381         if pr2 > 0:
> >> --> 382             return result.evalf(mlib.libmpf.prec_to_dps(pr))
> >>     383         return result
> >>     384
> >>
> >>
> >>
> /home/moorepants/miniconda3/lib/python3.5/site-packages/sympy/core/evalf.py
> >> in evalf(self, n, subs, maxn, chop, strict, quad, verbose)
> >>    1315             options['quad'] = quad
> >>    1316         try:
> >> -> 1317             result = evalf(self, prec + 4, options)
> >>    1318         except NotImplementedError:
> >>    1319             # Fall back to the ordinary evalf
> >>
> >>
> >>
> /home/moorepants/miniconda3/lib/python3.5/site-packages/sympy/core/evalf.py
> >> in evalf(x, prec, options)
> >>    1215             if 'subs' in options:
> >>    1216                 x = x.subs(evalf_subs(prec, options['subs']))
> >> -> 1217             re, im = x._eval_evalf(prec).as_real_imag()
> >>    1218             if re.has(re_) or im.has(im_):
> >>    1219                 raise NotImplementedError
> >>
> >>
> >>
> /home/moorepants/miniconda3/lib/python3.5/site-packages/sympy/core/function.py
> >> in _eval_evalf(self, prec)
> >>     484
> >>     485         with mpmath.workprec(prec):
> >> --> 486             v = func(*args)
> >>     487
> >>     488         return Expr._from_mpmath(v, prec)
> >>
> >>
> >>
> /home/moorepants/miniconda3/lib/python3.5/site-packages/sympy/mpmath/ctx_mp_python.py
> >> in __call__(self, prec, dps, rounding)
> >>     344         if not rounding: rounding = rounding2
> >>     345         if dps: prec = dps_to_prec(dps)
> >> --> 346         return self.context.make_mpf(self.func(prec, rounding))
> >>     347
> >>     348     @property
> >>
> >>
> >>
> /home/moorepants/miniconda3/lib/python3.5/site-packages/sympy/mpmath/libmp/libelefun.py
> >> in f(prec, rnd)
> >>     114     def f(prec, rnd=round_fast):
> >>     115         wp = prec + 20
> >> --> 116         v = fixed(wp)
> >>     117         if rnd in (round_up, round_ceiling):
> >>     118             v += 1
> >>
> >>
> >>
> /home/moorepants/miniconda3/lib/python3.5/site-packages/sympy/mpmath/libmp/libelefun.py
> >> in g(prec, **kwargs)
> >>      95         memo_prec = f.memo_prec
> >>      96         if prec <= memo_prec:
> >> ---> 97             return f.memo_val >> (memo_prec-prec)
> >>      98         newprec = int(prec*1.05+10)
> >>      99         f.memo_val = f(newprec, **kwargs)
> >>
> >> TypeError: unsupported operand type(s) for >>: 'int' and 'mpf'
> >>
> >> Can someone explain to me what is going on? I would expect "t" to be
> >> simply replaced with the number.
> >>
> >> Jason
> >> moorepants.info
> >> +01 530-601-9791
> >
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> >
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-- 
Regards
*Sartaj Singh*

*Mathematics and Computing*,
Indian Institute of Technology,
Varanasi - 221 005 INDIA

E-mail: [email protected], *[email protected]
<[email protected]>*

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