No, unfortunately, non-trivial relational assumptions like this are largely not implemented. As you may or may not know, the assumptions system in SymPy is currently in a bit of a mess. There are two assumptions systems, the "old" one, which is the one you used, and the "new" one, which uses ask() and Q.
Neither can handle this, or really any kind of non-trivial Add.is_positive type assumption. It's not even clear to me at the moment how one would go about implementing such things. Aaron Meurer On Fri, Feb 7, 2014 at 11:47 AM, Patrick O'Neill <[email protected]> wrote: > Howdy folks, > > I'm a very new to sympy, and am stumped by the following error. Considering > the following code snippet: > > from sympy import * > print sympy.__version__ > #'0.7.4.1-git' > epsilon,beta = var("epsilon,beta",positive=True) > (exp(epsilon*beta) - 1).is_positive # is None > > Sympy knows that beta and epsilon are positive, but seems not to know that > the exponential function takes positive quantities to quantities greater > than one. Is there a workaround for this issue, or is there something > fundamental to sympy's internals that makes this sort of deduction > impossible? > > I checked the mailing list, stack overflow and the issue tracker, and didn't > see anything pertaining to this question, but I admit I might not know what > I'm looking for. > > Thanks in advance! > > Cheers, > Pat. > > > On Fri, Feb 7, 2014 at 12:45 PM, Patrick O'Neill <[email protected]> wrote: >> >> Howdy folks, >> >> I'm a very new to sympy, and am stumped by the following error. >> Considering the following code snippet: >> >> from sympy import * >> print sympy.__version__ >> #'0.7.4.1-git' >> epsilon,beta = var("epsilon,beta",positive=True) >> (exp(epsilon*beta) - 1).is_positive # is None >> >> Sympy knows that beta and epsilon are positive, but seems not to know that >> the exponential function takes positive quantities to quantities greater >> than one. Is there a workaround for this issue, or is there something >> fundamental to sympy's internals that makes this sort of deduction >> impossible? >> >> I checked the mailing list, stack overflow and the issue tracker, and >> didn't see anything pertaining to this question, but I admit I might not >> know what I'm looking for. >> >> Thanks in advance! >> >> Cheers, >> Pat. > > > -- > 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. > For more options, visit https://groups.google.com/groups/opt_out. -- 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. For more options, visit https://groups.google.com/groups/opt_out.
