7 replaced http://mathematica.stackexchange.com/ with https://mathematica.stackexchange.com/ edited Apr 13 '17 at 12:55 Sorry, if this is a duplicate, I was not able to find a corresponding answer. The only question related to mine, as far as I can see it, is this one: How to solve algebra equations containing containing integration and parametersHow to solve algebra equations containing containing integration and parameters . But no answers were given. My problem: I have a nonlinear algebraic system for some unknown variables, say, $$a_1$$ and $$a_2$$, which are in a nonlinear integral of a function containing $$a_1$$ and $$a_2$$ over a region $$\Omega$$, e.g., an ellipse. The constant right hand side is also given. I really just have a nonlinear system. The integrals are not elementary, so I have to use some trick. Sorry, if this is a duplicate, I was not able to find a corresponding answer. The only question related to mine, as far as I can see it, is this one: How to solve algebra equations containing containing integration and parameters . But no answers were given. My problem: I have a nonlinear algebraic system for some unknown variables, say, $$a_1$$ and $$a_2$$, which are in a nonlinear integral of a function containing $$a_1$$ and $$a_2$$ over a region $$\Omega$$, e.g., an ellipse. The constant right hand side is also given. I really just have a nonlinear system. The integrals are not elementary, so I have to use some trick. Sorry, if this is a duplicate, I was not able to find a corresponding answer. The only question related to mine, as far as I can see it, is this one: How to solve algebra equations containing containing integration and parameters . But no answers were given. My problem: I have a nonlinear algebraic system for some unknown variables, say, $$a_1$$ and $$a_2$$, which are in a nonlinear integral of a function containing $$a_1$$ and $$a_2$$ over a region $$\Omega$$, e.g., an ellipse. The constant right hand side is also given. I really just have a nonlinear system. The integrals are not elementary, so I have to use some trick. 6 edited tags | link edited Oct 9 '15 at 14:45 J. M. will be back soon♦ 101k1010 gold badges317317 silver badges477477 bronze badges 5 added 2 characters in body edited Oct 2 '15 at 6:41 Mauricio Fernández 2,8731313 silver badges3434 bronze badges Until now, I am able to treat this using FindRoot and Integrate, but already for the 2D example given below this is kind of slow. I dont know if there is a way to use NIntegrate there. AlternativeAlternatively, I tried a rudimentary Newton algorithm and seems ok, see code below. Until now, I am able to treat this using FindRoot and Integrate, but already for the 2D example given below this is kind of slow. I dont know if there is a way to use NIntegrate there. Alternative, I tried a rudimentary Newton algorithm and seems ok, see code below. Until now, I am able to treat this using FindRoot and Integrate, but already for the 2D example given below this is kind of slow. I dont know if there is a way to use NIntegrate there. Alternatively, I tried a rudimentary Newton algorithm and seems ok, see code below. 4 added 9 characters in body edited Oct 2 '15 at 6:34 Mauricio Fernández 2,8731313 silver badges3434 bronze badges 3 added 433 characters in body edited Oct 2 '15 at 6:25 Mauricio Fernández 2,8731313 silver badges3434 bronze badges 2 added 52 characters in body edited Oct 1 '15 at 14:47 Mauricio Fernández 2,8731313 silver badges3434 bronze badges 1 asked Oct 1 '15 at 14:14 Mauricio Fernández 2,8731313 silver badges3434 bronze badges