def evalf_subs(prec, subs):
 newsubs = {}
 for (a, b) in subs.items():
  b = S(b)
  if b.is_Float:
   b = b._eval_evalf(prec)
  newsubs[a] = b
 return newsubs

def evalf_subs ( prec , subs ) : newsubs = { } for ( a , b ) in subs . items ( ) : b = S ( b ) if b . is_Float : b = b . _eval_evalf ( prec ) newsubs [ a ] = b return newsubs
change all float entries in subs to have precision prec .