in evalf routines in numbers, don't evalf until it's know that foo is a number
in evalf routines in numbers, don't evalf until it's know that foo is a number

    In a few places, an evaluation was being performed and then a test
    of whether the result is a number or not was being made. This caused
    problems with the evalf routine which is expecting to work with numbers.

    An example of a failure:

    >>> b = Symbol('b', positive=True)
    >>> oo**polar_lift(-b+1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "sympy\core\decorators.py", line 65, in __sympifyit_wrapper
    return func(a, sympify(b, strict=True))
  File "sympy\core\decorators.py", line 105, in binary_op_wrapper
    return func(self, other)
  File "sympy\core\expr.py", line 129, in __pow__
    return Pow(self, other)
  File "sympy\core\cache.py", line 91, in wrapper
    func_cache_it_cache[k] = r = func(*args, **kw_args)
  File "sympy\core\power.py", line 84, in __new__
    obj = b._eval_power(e)
  File "sympy\core\numbers.py", line 1705, in _eval_power
    n = exp.evalf()
  File "sympy\core\evalf.py", line 1055, in evalf
    result = evalf(self, prec+4, options)
  File "sympy\core\evalf.py", line 986, in evalf
    re = re._to_mpmath(prec, allow_ints=False)._mpf_
  File "sympy\core\evalf.py", line 1122, in _to_mpmath
    raise ValueError(errmsg)
ValueError: cannot convert to mpmath number

lindsayad/sympy,farhaanbukhsh/sympy,kmacinnis/sympy,MridulS/sympy,garvitr/sympy,emon10005/sympy,grevutiu-gabriel/sympy,Gadal/sympy,AkademieOlympia/sympy,mafiya69/sympy,jerli/sympy,pandeyadarsh/sympy,chaffra/sympy,sunny94/temp,kevalds51/sympy,sahmed95/sympy,abhiii5459/sympy,cccfran/sympy,ChristinaZografou/sympy,ga7g08/sympy,dqnykamp/sympy,asm666/sympy,liangjiaxing/sympy,chaffra/sympy,jbbskinny/sympy,toolforger/sympy,lidavidm/sympy,Vishluck/sympy,kaushik94/sympy,Vishluck/sympy,moble/sympy,sampadsaha5/sympy,Curious72/sympy,meghana1995/sympy,hargup/sympy,jaimahajan1997/sympy,wyom/sympy,souravsingh/sympy,yukoba/sympy,yashsharan/sympy,Sumith1896/sympy,abloomston/sympy,oliverlee/sympy,kaichogami/sympy,MechCoder/sympy,hargup/sympy,jamesblunt/sympy,vipulroxx/sympy,dqnykamp/sympy,pbrady/sympy,jaimahajan1997/sympy,Arafatk/sympy,AkademieOlympia/sympy,Titan-C/sympy,hrashk/sympy,sampadsaha5/sympy,atreyv/sympy,diofant/diofant,iamutkarshtiwari/sympy,MridulS/sympy,shipci/sympy,yashsharan/sympy,jamesblunt/sympy,MridulS/sympy,wanglongqi/sympy,cccfran/sympy,srjoglekar246/sympy,Gadal/sympy,mafiya69/sympy,wanglongqi/sympy,asm666/sympy,yukoba/sympy,vipulroxx/sympy,sampadsaha5/sympy,chaffra/sympy,abhiii5459/sympy,sahilshekhawat/sympy,sunny94/temp,saurabhjn76/sympy,ChristinaZografou/sympy,skidzo/sympy,madan96/sympy,aktech/sympy,AunShiLord/sympy,saurabhjn76/sympy,Davidjohnwilson/sympy,wyom/sympy,madan96/sympy,pbrady/sympy,emon10005/sympy,madan96/sympy,Designist/sympy,vipulroxx/sympy,jbbskinny/sympy,Mitchkoens/sympy,ahhda/sympy,aktech/sympy,skirpichev/omg,beni55/sympy,bukzor/sympy,sahmed95/sympy,AunShiLord/sympy,shikil/sympy,pbrady/sympy,Mitchkoens/sympy,sahilshekhawat/sympy,debugger22/sympy,Arafatk/sympy,Shaswat27/sympy,VaibhavAgarwalVA/sympy,ahhda/sympy,grevutiu-gabriel/sympy,lindsayad/sympy,lidavidm/sympy,atsao72/sympy,yashsharan/sympy,lindsayad/sympy,jaimahajan1997/sympy,cccfran/sympy,aktech/sympy,Titan-C/sympy,jerli/sympy,saurabhjn76/sympy,VaibhavAgarwalVA/sympy,wanglongqi/sympy,dqnykamp/sympy,yukoba/sympy,debugger22/sympy,asm666/sympy,amitjamadagni/sympy,drufat/sympy,kumarkrishna/sympy,wyom/sympy,Arafatk/sympy,MechCoder/sympy,maniteja123/sympy,Sumith1896/sympy,kumarkrishna/sympy,jerli/sympy,ahhda/sympy,Sumith1896/sympy,kevalds51/sympy,souravsingh/sympy,jamesblunt/sympy,drufat/sympy,toolforger/sympy,Curious72/sympy,sahilshekhawat/sympy,kmacinnis/sympy,atreyv/sympy,mcdaniel67/sympy,abloomston/sympy,atsao72/sympy,AunShiLord/sympy,Davidjohnwilson/sympy,grevutiu-gabriel/sympy,cswiercz/sympy,pandeyadarsh/sympy,mcdaniel67/sympy,meghana1995/sympy,bukzor/sympy,toolforger/sympy,oliverlee/sympy,garvitr/sympy,Davidjohnwilson/sympy,shipci/sympy,shikil/sympy,kumarkrishna/sympy,souravsingh/sympy,VaibhavAgarwalVA/sympy,sahmed95/sympy,iamutkarshtiwari/sympy,oliverlee/sympy,farhaanbukhsh/sympy,ChristinaZografou/sympy,flacjacket/sympy,cswiercz/sympy,hargup/sympy,Gadal/sympy,debugger22/sympy,mcdaniel67/sympy,atreyv/sympy,emon10005/sympy,Titan-C/sympy,beni55/sympy,liangjiaxing/sympy,Shaswat27/sympy,hrashk/sympy,iamutkarshtiwari/sympy,rahuldan/sympy,Mitchkoens/sympy,amitjamadagni/sympy,ga7g08/sympy,moble/sympy,jbbskinny/sympy,garvitr/sympy,maniteja123/sympy,cswiercz/sympy,postvakje/sympy,Curious72/sympy,ga7g08/sympy,kaichogami/sympy,kaichogami/sympy,skidzo/sympy,abloomston/sympy,atsao72/sympy,Vishluck/sympy,postvakje/sympy,Designist/sympy,shipci/sympy,Designist/sympy,rahuldan/sympy,hrashk/sympy,sunny94/temp,moble/sympy,mafiya69/sympy,kaushik94/sympy,MechCoder/sympy,kevalds51/sympy,skidzo/sympy,kaushik94/sympy,bukzor/sympy,rahuldan/sympy,liangjiaxing/sympy,pandeyadarsh/sympy,kmacinnis/sympy,shikil/sympy,AkademieOlympia/sympy,lidavidm/sympy,beni55/sympy,maniteja123/sympy,drufat/sympy,Shaswat27/sympy,farhaanbukhsh/sympy,postvakje/sympy,abhiii5459/sympy,meghana1995/sympy