On Tue, Sep 8, 2015 at 2:36 PM, Ondřej Čertík <[email protected]> wrote: > On Thu, Sep 3, 2015 at 8:41 AM, Titas Chanda <[email protected]> wrote: >> #### I have already posted it on github. ####### > > Please post a link, so that people don't need to search for it. > >> >> >> >> Hi, >> >> >> sympy sqrt and conjuagte are not commuting for symbols.... >> >> >> >> >> import sympy as sm >> a = sm.Symbol('a') >> sm.sqrt(sm.conjugate(a)) == sm.conjugate(sm.sqrt(a)) >> False >> >> >> >> They are not even cancelling each other.... > > That's because they are not equal to each other. Just try some numbers: > > In [1]: from cmath import sqrt > > In [2]: a = -1 > > In [3]: sqrt(a.conjugate()) > Out[3]: 1j > > In [4]: sqrt(a).conjugate() > Out[4]: -1j > > If you want to understand why, I have thorough notes here: > > http://www.theoretical-physics.net/dev/math/complex.html > > Let me know if you have any questions.
I've added your example into this section: http://www.theoretical-physics.net/dev/math/complex.html#id1 As you can see, there is an extra minus factor when "a" is on the negative real axis (like -1, -2, ...). Ondrej > > Ondrej > >> >> >> Thanks.... >> >> -- >> 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/4f16f8f3-c32e-4d00-989c-e914a2923793%40googlegroups.com. >> For more options, visit https://groups.google.com/d/optout. -- 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/CADDwiVDM4pUUAQnr5UbPQnUa86p7zWAHjLZSOjU0_qgPQHuq%2BQ%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
