solving an inequality
in [Matlab]
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From: ehsan on 31 May 2010 07:10 Hi, I have a system of inequality consisting of a lot of inequalities. How can I find if it has any answer or not, or possibly find a solution for it? thanks
From: us on 31 May 2010 07:19 "ehsan " <ehsan.safavieh(a)gmail.com> wrote in message <hu05ed$k2l$1(a)fred.mathworks.com>... > Hi, > > I have a system of inequality consisting of a lot of inequalities. How can I find if it has any answer or not, or possibly find a solution for it? > > thanks what have YOU done so far to solve YOUR particular problem... us
From: Bruno Luong on 31 May 2010 07:24 "ehsan " <ehsan.safavieh(a)gmail.com> wrote in message <hu05ed$k2l$1(a)fred.mathworks.com>... > Hi, > > I have a system of inequality consisting of a lot of inequalities. How can I find if it has any answer or not, or possibly find a solution for it? No easily in general. Bruno
From: John D'Errico on 31 May 2010 09:13 "ehsan " <ehsan.safavieh(a)gmail.com> wrote in message <hu05ed$k2l$1(a)fred.mathworks.com>... > Hi, > > I have a system of inequality consisting of a lot of inequalities. How can I find if it has any answer or not, or possibly find a solution for it? > > thanks Usually, if there are any solutions, there are infinitely many. But finding A single solution is not so easy. Are they linear inequalities or nonlinear? Nonlinear problems are significantly more difficult. You can always use a tool like lsqlin or fmincon to find a solution if one exists. John
From: ehsan on 2 Jun 2010 07:52
"ehsan " <ehsan.safavieh(a)gmail.com> wrote in message <hu05ed$k2l$1(a)fred.mathworks.com>... > Hi, > > I have a system of inequality consisting of a lot of inequalities. How can I find if it has any answer or not, or possibly find a solution for it? > > thanks Thank you guys, My problem is a set of inequalities like: (A+xi)/(B-yi) > (C+xi)/(D+yi) , xi^2+yi^2=E , xi > xi+1 , yi < yi+1 ; i=1:n The problem with fmincon, lsqlin, ... is that they try to minimize a FUNCTION regarding some equalities and inequalities, but I don't have any function to minimize. I just want a feasible solution or interval for the variables. I tried to use maple -> solve function but it didn't work: >>maple( 'solve({((A+e1)/(B-ep1))<((C+2*ep2)/(D+2*e2)), ((C+2*ep2)/(D+2*e2))< ((A+2*e2)/(B-2*ep2)), e1<e2, ep1>ep2 })' ) Warning: Warning, solutions may have been lost (perhaps my problem had no answer) do you know any other tools or tricks? |