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 Mar 28 comment The numerical solution of a nonlinear ODE: boundary value problem Could you please cite the paper by any chance? Thank you. Mar 26 comment The numerical solution of a nonlinear ODE: boundary value problem Could this be a version related issue? I just started a fresh kernel and the problem solved fine "right out of the box" using NDSolveValue: NDSolveValue[{(y^\[Prime]\[Prime])[x] == 204/100 (1 - x) (1 + Derivative[1][y][x]^2)^(1/2 ) + ( 1 + Derivative[1][y][x]^2)/y[x], y[0] == 1, y[1] == 1}, y[x], {x, 0, 1}] Mar 26 comment The numerical solution of a nonlinear ODE: boundary value problem Could you share a little about the physics that this equation is solving? That way someone may be able to tell you about any well established boundary condition issue or specification with physical insight, perhaps? It would seem that it is the final term in your equation (1 + Derivative[1][y][x]^2)/y[x] causing the issue. Feb 21 comment How to solve 3D heat equation with Neumann B.C Firstly, it would seem that BC1 has not been defined. I assume this is an initial condition? Feb 20 comment Implementing a boundary condition that is dependent on the solution Could you post your problem statement along with the code? Seems like the heat equation.... with two BCs defined at x=L? Describing the physics may help. Feb 13 comment Is it possible to make a mathematica program which can be viewed online by anyone? This asks me to sign in with my Wolfram ID and password. I guess "public" would need to have a Wolfram ID to access this manipulate object? Feb 7 comment Using NDSolve to find particle trajectory what is the difference with this. In the latter answer, the author did not have to make m a 3D vector. In the current problem, is it the addition of q*E that leads to two matrices that may not be "added" together? Feb 7 comment Using NDSolve to find particle trajectory EquationSimplification->"Residual" is magic? Feb 7 comment Using NDSolve to find particle trajectory I haven't worked with vectors in Mathematica so I may not be able to help with that. However, your ParametricPlot3D has incorrect syntax. Assuming that pos is the position, is your initial acceleration zero? Feb 6 comment Lyapunov Exponent Yes, this package is golden! Its awesome. Feb 6 comment WhenEvent and Resetting of Variable in PDE when operation succeeds @march Indeed! Wow! Was that an easy fix or what... Feb 6 comment WhenEvent and Resetting of Variable in PDE when operation succeeds @Dr.belisarius So, how do I proceed? I am sorry but I do not have a clue. What you say makes sense. Feb 3 comment Phase Portrait to Differential Equation @Searke Good point. However, I do mention given data that made the phase portrait. Feb 3 comment Phase Portrait to Differential Equation Curious to know why this received a "close" request? Jan 30 comment How can I solve a 3D heat transfer partial differential equation? Try looking up NDSolve and NDSolveValue. They both demonstrate the heat equation in (x,y,t). You should be able to extend that to (x,y,z,t). Two-Dim code. Jan 16 comment Heat convection differential equations from 1952 - Mathematica “fails to converge” @xzczd Could you share a link (if on SE, i.e) to the issue you were having with the Young-Laplace equation? I would be interested to look at it. I am into analytical fluid dynamics and heat transfer and mathematica has revolutionized it for me! Jan 16 comment How do I solve a PDE with a strange boundary condition? @xzczdYou worked this problem from a robust fundamental theory put forth by Boris Galerkin!! Bad news for the folks at mathematica ;).. for you'll put them out of business ;)!!! With your permission, I would like to demonstrate your answer to my undergraduate class (that I teach) on FEM. Jan 16 comment Heat convection differential equations from 1952 - Mathematica “fails to converge” @xzczd Yes, this (both F and H) will be asymptotic in the far field. I found a mathematica file that uses the Shooting method by expressing one of these coupled variables as an initial condition. Alas, I do not have the time to express this here because of a lack of time today! I'll try to get to it in the evening. Jan 15 comment Heat convection differential equations from 1952 - Mathematica “fails to converge” I just found this. I'll experiment with this and add more detail to this problem. Nov 13 comment Solution of Poisson equation with two regions Can this be a case for "matched asymptotics" (perturbation methods)?.. or am I over-complicating the problem?