Eigenvalue bounds












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I am looking for any information on the bounds of the eigenvalues of the cubic spline interpolation matrix when all the values are positive. The bounds in question are:



$$frac{1}{6} Min(x_n) le |lambda| le Max(x_n) $$



This should hold for any eigenvalue of the matrix and the matrix looks like



$$
begin{bmatrix} frac{x_0}{3} & frac{x_0}{6} & 0 & ... \ frac{x_0}{6} & frac{x_0 + x_1}{6} & frac{x_1}{6} & 0 & ... \ 0 & frac{x_1}{6} & frac{x_1 + x_2}{3} & frac{x_2}{6} & 0 & ... \ 0 & 0 & ... \ 0 & 0 & 0 & frac{x_{n-2}}{6} & frac{x_{n-2} + x_{n-1}}{3} & frac{x_{n-1}}{6} \ 0 & 0 & 0 & 0 & frac{x_{n-1}}{6} & frac{x_{n-1}}{3}
end{bmatrix}$$

Is there a name for this bounds and where it comes from would be helpful.










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  • You seem to have at least one typo.
    – Ian
    Dec 1 at 4:56












  • In any case the upper bound is quite suboptimal, you can easily use Gerschgorin's theorem to make the coefficient be $2/3$ instead. The lower bound is more problematic.
    – Ian
    Dec 1 at 4:58
















0














I am looking for any information on the bounds of the eigenvalues of the cubic spline interpolation matrix when all the values are positive. The bounds in question are:



$$frac{1}{6} Min(x_n) le |lambda| le Max(x_n) $$



This should hold for any eigenvalue of the matrix and the matrix looks like



$$
begin{bmatrix} frac{x_0}{3} & frac{x_0}{6} & 0 & ... \ frac{x_0}{6} & frac{x_0 + x_1}{6} & frac{x_1}{6} & 0 & ... \ 0 & frac{x_1}{6} & frac{x_1 + x_2}{3} & frac{x_2}{6} & 0 & ... \ 0 & 0 & ... \ 0 & 0 & 0 & frac{x_{n-2}}{6} & frac{x_{n-2} + x_{n-1}}{3} & frac{x_{n-1}}{6} \ 0 & 0 & 0 & 0 & frac{x_{n-1}}{6} & frac{x_{n-1}}{3}
end{bmatrix}$$

Is there a name for this bounds and where it comes from would be helpful.










share|cite|improve this question
























  • You seem to have at least one typo.
    – Ian
    Dec 1 at 4:56












  • In any case the upper bound is quite suboptimal, you can easily use Gerschgorin's theorem to make the coefficient be $2/3$ instead. The lower bound is more problematic.
    – Ian
    Dec 1 at 4:58














0












0








0







I am looking for any information on the bounds of the eigenvalues of the cubic spline interpolation matrix when all the values are positive. The bounds in question are:



$$frac{1}{6} Min(x_n) le |lambda| le Max(x_n) $$



This should hold for any eigenvalue of the matrix and the matrix looks like



$$
begin{bmatrix} frac{x_0}{3} & frac{x_0}{6} & 0 & ... \ frac{x_0}{6} & frac{x_0 + x_1}{6} & frac{x_1}{6} & 0 & ... \ 0 & frac{x_1}{6} & frac{x_1 + x_2}{3} & frac{x_2}{6} & 0 & ... \ 0 & 0 & ... \ 0 & 0 & 0 & frac{x_{n-2}}{6} & frac{x_{n-2} + x_{n-1}}{3} & frac{x_{n-1}}{6} \ 0 & 0 & 0 & 0 & frac{x_{n-1}}{6} & frac{x_{n-1}}{3}
end{bmatrix}$$

Is there a name for this bounds and where it comes from would be helpful.










share|cite|improve this question















I am looking for any information on the bounds of the eigenvalues of the cubic spline interpolation matrix when all the values are positive. The bounds in question are:



$$frac{1}{6} Min(x_n) le |lambda| le Max(x_n) $$



This should hold for any eigenvalue of the matrix and the matrix looks like



$$
begin{bmatrix} frac{x_0}{3} & frac{x_0}{6} & 0 & ... \ frac{x_0}{6} & frac{x_0 + x_1}{6} & frac{x_1}{6} & 0 & ... \ 0 & frac{x_1}{6} & frac{x_1 + x_2}{3} & frac{x_2}{6} & 0 & ... \ 0 & 0 & ... \ 0 & 0 & 0 & frac{x_{n-2}}{6} & frac{x_{n-2} + x_{n-1}}{3} & frac{x_{n-1}}{6} \ 0 & 0 & 0 & 0 & frac{x_{n-1}}{6} & frac{x_{n-1}}{3}
end{bmatrix}$$

Is there a name for this bounds and where it comes from would be helpful.







linear-algebra matrices eigenvalues-eigenvectors






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edited Dec 1 at 4:58

























asked Dec 1 at 4:51









user621595

11




11












  • You seem to have at least one typo.
    – Ian
    Dec 1 at 4:56












  • In any case the upper bound is quite suboptimal, you can easily use Gerschgorin's theorem to make the coefficient be $2/3$ instead. The lower bound is more problematic.
    – Ian
    Dec 1 at 4:58


















  • You seem to have at least one typo.
    – Ian
    Dec 1 at 4:56












  • In any case the upper bound is quite suboptimal, you can easily use Gerschgorin's theorem to make the coefficient be $2/3$ instead. The lower bound is more problematic.
    – Ian
    Dec 1 at 4:58
















You seem to have at least one typo.
– Ian
Dec 1 at 4:56






You seem to have at least one typo.
– Ian
Dec 1 at 4:56














In any case the upper bound is quite suboptimal, you can easily use Gerschgorin's theorem to make the coefficient be $2/3$ instead. The lower bound is more problematic.
– Ian
Dec 1 at 4:58




In any case the upper bound is quite suboptimal, you can easily use Gerschgorin's theorem to make the coefficient be $2/3$ instead. The lower bound is more problematic.
– Ian
Dec 1 at 4:58















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