On Mon, Mar 1, 2021 at 4:58 PM Oscar Benjamin <[email protected]> wrote:
> On Mon, 1 Mar 2021 at 13:43, Bruno Nicenboim <[email protected]> > wrote: > > > > On Fri, Feb 26, 2021 at 9:01 PM Oscar Benjamin < > [email protected]> wrote: > >> > >> I don't think your constraints are enough to determine what the > >> correct solution should be. For example if we have the values: > >> {mu_1:1, mu_2:2, tau:2, psi:1, x:2} > >> > >> Then neither solution satisfies the constraint: > > > > yes, it's true. I realize that a missing piece of information is that > psi < min(mu_1,mu_2,x). Is there a way to include this to get only one > solution from solveset? > > > > And is changing the domain of solveset the right approach? > > In principle yes, but I wouldn't be surprised if `solveset` is unable > to handle a case like this. > > There isn't really a sympy function that handles this kind of case. > The solve function can handle a mix of equations and inequalities but > it doesn't treat them in the way that you want. The solveset function > is only for a single equation so you would have to encode the > inequality constraints in the domain somehow (which is not so easy for > the last constraint you have shown). > ok, thanks! But for example here: ``` K_pp = tau**2*(2*mu_1**2*mu_2**2*t**2*tau**4 + mu_1**2 + mu_2**2 + t*(-2*mu_1**2*mu_2*tau**2 - 2*mu_1*mu_2**2*tau**2))/((mu_1*t*tau**2 - 1)**2*(mu_2*t*tau**2 - 1)**2) ``` This is another version without the psi, so the two constraints for t should be enough. But this is still giving me two solutions ``` cset = ConditionSet(t, t < 1/(mu_1 * tau**2)).intersect(ConditionSet(t, t < 1/(mu_1 * tau**2))) s_x = solveset(K_p - x, t, domain=cset) ``` As follows. ``` Intersection(ConditionSet(t, t < 1/(mu_1*tau**2)), {(-2*mu_1*mu_2 + mu_1*x + mu_2*x)/(2*mu_1*mu_2*tau**2*x) - sqrt(4*mu_1**2*mu_2**2 + mu_1**2*x**2 - 2*mu_1*mu_2*x**2 + mu_2**2*x**2)/(2*mu_1*mu_2*tau**2*x), (-2*mu_1*mu_2 + mu_1*x + mu_2*x)/(2*mu_1*mu_2*tau**2*x) + sqrt(4*mu_1**2*mu_2**2 + mu_1**2*x**2 - 2*mu_1*mu_2*x**2 + mu_2**2*x**2)/(2*mu_1*mu_2*tau**2*x)}) \ Intersection(ConditionSet(t, t < 1/(mu_1*tau**2)), {1/(mu_2*tau**2)}) ``` I understand correctly that this is the right approach, but solveset is just unable to find the right solution given the specific domain? > > There has been discussion recently on this last about adding a solver > for systems of inequalities. > > -- > Oscar > > -- > You received this message because you are subscribed to a topic in the > Google Groups "sympy" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/sympy/oIKJ0nJHZC8/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/CAHVvXxQgpaZZOCAefpBpXPfLE3PnuvDnfuaN%2BdU50d%2B244RZnQ%40mail.gmail.com > . > -- Bests, Bruno Nicenboim -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAHRDyEa9EMRmLA%3D596G%2BxWwyMtxS-%3DGOE9yBUtsA68tgpZ9eiQ%40mail.gmail.com.
