KonkurStudy

سوال ۱۷ کنکور ارشد ریاضی ۱۴۰۰

اهمیت
۰/۵

PASSAGE 1 — Number of Steps, Work per Step, and Preconditioning (excerpt, paragraph 2):

"We shall see that the number of steps required for convergence to a satisfactory precision typically depends on spectral properties of the matrix A, if the word "spectral" is interpreted broadly. For example, the conjugate gradient iteration is guaranteed to solve a hermitian positive definite system Ax=bAx=b quickly if the eigenvalues of A are clustered well away from the origin. Similarly, the Lanczos iteration is guaranteed to compute certain eigenvalues of a real hermitian matrix quickly if those eigenvalues are well separated from the rest of the spectrum (and if the initial vector that starts the iteration is suitably generic)."

17- If the Eigen values of the hermitian positive definite matrix A are not clustered around the origin, then one -------------.

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