Consider the following logarithmic equation: log(3*x) - log(1 - x) - log(4*x + 1)
Wolfram alpha <http://www.wolframalpha.com/input/?i=solve(log(3*x)+-+log(-x++%2B+1)+-+log(4*x+%2B+1),+x)> gives the result as `-1/2` and `1/2`, but mentions `-1/2` is only valid when considering complex valued logarithm. So to solve this equation in the `Real` domain, should `-1/2` be considered as a solution because substituting it in the equation will give log with negative argument and I suppose (I am not sure though) it should not be considered in the real domain When these solutions are checked using checksol() <https://github.com/sympy/sympy/blob/master/sympy/solvers/solvers.py#L173> the result is `True` for both the cases because the `I*pi` terms get canceled out. A brief background of this situation: I was implementing log solver for `_transolve` in #14792 <https://github.com/sympy/sympy/pull/14792> and the idea is to convert the equation into a single instance of `log` (using `logcombine`) which can further be solved by passing it to `_solveset`, but result returned from `solveset` can have unwanted solutions (see this test <https://github.com/sympy/sympy/pull/14792/files#diff-eec0422923e8f100745c015cd8fdd6cfR994>). To remove such solutions `checksol()` can be used but it possesses a problem as mentioned above, so I tried a different approach to remove these solutions (see here <https://github.com/sympy/sympy/pull/14792/files#diff-eec0422923e8f100745c015cd8fdd6cfR994> ) The problem is what should be done here, should such solutions be considered? If not is the approach used efficient enough to remove logarithmic singularities? -- 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 https://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/c3915e4d-bb5d-443c-b38c-5f8aa2696478%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
