Chapter 7: Problem 1
Find the three-digit decimal floating-point representation of each of the following numbers: (a) 2312 (b) 32.56 (c) 0.01277 (d) 82,431
/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none}
Learning Materials
Features
Discover
Chapter 7: Problem 1
Find the three-digit decimal floating-point representation of each of the following numbers: (a) 2312 (b) 32.56 (c) 0.01277 (d) 82,431
All the tools & learning materials you need for study success - in one app.
Get started for free
Let \\[ A=\left(\begin{array}{rr} 1 & 2 \\ -1 & -1 \end{array}\right) \quad \text { and } \quad \mathbf{u}_{0}=\left(\begin{array}{l} 1 \\ 1 \end{array}\right) \\] (a) Compute \(\mathbf{u}_{1}, \mathbf{u}_{2}, \mathbf{u}_{3},\) and \(\mathbf{u}_{4},\) using the power method. (b) Explain why the power method will fail to converge in this case.
Suppose that \(A^{-1}\) and the \(L U\) factorization of \(A\) have already been determined. How many scalar additions and multiplications are necessary to compute \(A^{-1} \mathbf{b} ?\) Compare this number with the number of operations required to solve \(L U \mathbf{x}=\mathbf{b}\) using \(\mathrm{Al}\) gorithm \(7.2 .2 .\) Suppose that we have a number of systems to solve with the same coefficient matrix \(A .\) Is it worthwhile to compute \(A^{-1} ?\) Explain.
Let \(A=Q_{1} R_{1}=Q_{2} R_{2},\) where \(Q_{1}\) and \(Q_{2}\) are orthogonal and \(R_{1}\) and \(R_{2}\) are both upper triangular and nonsingular. (a) Show that \(Q_{1}^{T} Q_{2}\) is diagonal. (b) How do \(R_{1}\) and \(R_{2}\) compare? Explain.
Let \(A=X Y^{T}\), where \(X\) is an \(m \times r\) matrix, \(Y^{T}\) is an \(r \times n\) matrix, and \(X^{T} X\) and \(Y^{T} Y\) are both nonsingular. Show that the matrix \\[ B=Y\left(Y^{T} Y\right)^{-1}\left(X^{T} X\right)^{-1} X^{T} \\] satisfies the Penrose conditions and hence must equal \(A^{+} .\) Thus, \(A^{+}\) can be determined from any factorization of this form.
Let \(A\) be a nonsingular \(n \times n\) matrix and let \(Q\) be an \(n \times n\) orthogonal matrix. Show that (a) \(\operatorname{cond}_{2}(Q A)=\operatorname{cond}_{2}(A Q)=\operatorname{cond}_{2}(A)\) (b) if \(B=Q^{T} A Q,\) then \(\operatorname{cond}_{2}(B)=\operatorname{cond}_{2}(A)\)
What do you think about this solution?
We value your feedback to improve our textbook solutions.