Frobenius Definition and 107 Threads

  1. E

    Solving ODEs with Frobenius Method: Troubleshooting and Tips

    i need your help...i had to solve some ode using the frobenius method but half-way through i stuck... for the first ode i didn't know what to do when i had to multiply the sinx and cosx with y,y',y" ii)i had a problem because of the cosx and i couldn't equate the series...--->second ode...
  2. J

    Differential Equation: Frobenius

    My problem: find the first solution and use it to find the second solution for x^2*y"-x*y'+(x^2+1)y=0 assuming y=summation from n=0 to infinity for An*x^n+r substituting and solving gives me r=1 and a general equation: An=A(n-2)/((n+r)*(n+r-2)+1) for n >= 2 plugging r into my...
  3. J

    Frobenius Method: Finding Solutions for x^2*y"-x*y'+(x^2+1)y=0

    Somebody please help, I'm not sure I know what is going on with this. My problem: find the first solution and use it to find the second solution for x^2*y"-x*y'+(x^2+1)y=0 assuming y=summation from n=0 to infinity for An*x^n+r substituting and solving gives me r=1 and a general...
  4. A

    Solution to Frobenius Problem for N=2: Proof?

    does anyone know a proof for the solution to the frobenius problem for n=2? that is, that the smallest not possible number expressable as a linear combination of a and b is (a-1)(b-1)??
  5. M

    Another question dealing with Frobenius method

    This is another question I have trouble proving: Suppose the coefficients of the equation: w'' + p(z)w' + q(z)w = 0 are analytic and single-valued in a punctured neighborhood of the origin. Suppose it is known that the function w(z) = f(z) ln z is a solution, where f is analytic and...
  6. S

    Frobenius method with imaginary powers

    I need to solve a linear, second order, homogeneous ODE, and I'm using the Frobenius method. This amounts to setting: y = \sum_{n=0}^{\infty} c_n x^{n+k} then getting y' and y'', plugging in, combining like terms, and setting the coefficient of each term to 0 to solve for the cn's. This...
  7. C

    Proving Frobenius Norm of Matrix A

    Hi I'm in the process of proving a matrix norm. The Frobenius norm is defined by an nxn matrix A by ||A||_F=sum[(|aij|^2)^(1/2) i=1..n,j=1..n] I'm having trouble showing ||A+B|| <= ||A|| + ||B|| thanks for the help
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