please, I need help! I don't find the solution to my ODE using bvp4c solver.

Hello,

• I have already asked my question, and remarks pushed me to revise my program, but I still get errors.
• I have a fourth order ODE/BVP. It describes the stream function in the flow of turbulent gas above a liquid fluid film flowing over an inclined plane.
• I use the bvp4c solver to solve this EDO/BVP. This is the solver that used the author of the article on which I work.
• Two errors are displayed compiling program.
• I attach the program that I do. Could you please help me understand and solve the problem? I will be very grateful.

[Torsten]

You forgot to include the error messages.

Best wishes

Torsten.

[Nadjah]

error messages are:

1. Error using alpha.Too many output arguments.
2. Error in exo3_bvp (line 17)sol = bvp4c(@odes,@bcs,solinit,alpha)

Thank you.

[Torsten]

In the program documentation, you write that alpha is an unknown parameter.

Is this true ?

Best wishes

Torsten.

[Nadjah]

Yes, it is true.

Answer 1

[Torsten]

a) If alpha is to be determined by bvp4c, then

1. Change the call to bvp4c from

sol = bvp4c(@odes,@bcs,solinit,alpha);

to

sol = bvp4c(@odes,@bcs,solinit);

2. You will Need to supply a forth boundary condition in function "odes".

Take a look at the example

Compute Fourth Eigenvalue of Mathieu's Equation

under

http://de.mathworks.com/help/matlab/ref/bvp4c.html

b) The x-array in your function "odes" is supplied by bvp4c. So you can't redefine it as

x=0:0.001:200;

Calculate derivatives of your function psi1 before calling bvp4c on your preferred x-grid and use interp1 to interpolate the derivatives at the points required by bvp4c in "odes".

Best wishes

Torsten.

[Torsten]

Should read

2. You will need to supply a fifth boundary condition in function "odes".

Best wishes

Torsten.