Yes, It is a bug Indeed. Thanks for reporting. Fixed in this PR: https://github.com/sympy/sympy/pull/9231 Please have a look.
*Reference:* http://functions.wolfram.com/ElementaryFunctions/ArcCosh/02/ http://www.wolframalpha.com/input/?i=ArcCosh%5B-z%5D On Tuesday, March 31, 2015 at 8:10:18 PM UTC+5:30, Arnaud Usciati wrote: > > Hello everybody, > > I tried values with acosh function and I found an issue. > Suppose x = symbols('x', real=True) and f = lambda x: acosh(-x). > > For instance : > > Input : f(1) > > Output : I*pi > --> That's OK > > > Input : f(-1) > > Output : 0 > --> That's OK > > But f(x) returns -acosh(x) instead of acosh(-x) ! It's wrong because > 'acosh' it's certainly not odd !! > > Arnaud > > > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/0edb8ee5-af2c-4fec-9d0b-5665ae7edef1%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
