This problem deals with the instability of polynomial root finding. First, note how MATLAB handles polynomial operations by doing some simple computations. A polynomial, in MATLAB is andimensional vector, where is the coefficient of is the coefficient ofn−2 is the coefficient of0.
Show how to represent the polynomial43in MATLAB.
To multiply two polynomials, use the MATLAB function conv. For instance, to compute the coefficients of (2 proceed as follows:
Using conv find the coefficients of4 and assign them to the vector
Using the MATLAB function roots, compute the roots of 4 Explain the results.
Letibe the coefficient ofiin polynomial and be a simple root of Suppose roundoff error perturbsiby an amountiso the root now becomes Does a smalliresult in a small We can answer that question if we have a formula for the condition number,
ai for the computation. By applying Theorem 2.1 in Ref. [30],
Use this result in Problems 10.33 and 10.34.
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