- 220.127.116.11.169: Vertical strip) If the a~sumptions of Theorems I and 2 are satisfie...
- 18.104.22.168.170: (Existence?) Does the initial value problem (x - l)y' = 2y, y(l) = ...
- 22.214.171.124.171: (Common points) Can two solution curves of the same ODE have a comm...
- 126.96.36.199.172: (Change of initial condition) What happens in Prob. 2 if you replac...
- 188.8.131.52.173: (Linear ODE) If p and I' in y' + p(x)y = rex) are continuous for al...
- 184.108.40.206.174: (Three possible cases) Find all initial conditions such that lx2 - ...
- 220.127.116.11.175: (Length of x-interval) In most cases the solution of an initial val...
- 18.104.22.168.176: PROJECT. Lipschitz Condition. (A) State the definItion of a Lipschi...
- 22.214.171.124.177: Maximum a) What IS the largest possible a In Example I in the text?
- 126.96.36.199.178: CAS PROJECT. Picard Iteration. (A) Show that by integrating the ODE...
Solutions for Chapter 1.7: Existence and Uniqueness of Solutions
Full solutions for Advanced Engineering Mathematics | 9th Edition
peA) = det(A - AI) has peA) = zero matrix.
Change of basis matrix M.
The old basis vectors v j are combinations L mij Wi of the new basis vectors. The coordinates of CI VI + ... + cnvn = dl wI + ... + dn Wn are related by d = M c. (For n = 2 set VI = mll WI +m21 W2, V2 = m12WI +m22w2.)
Column picture of Ax = b.
The vector b becomes a combination of the columns of A. The system is solvable only when b is in the column space C (A).
z = a - ib for any complex number z = a + ib. Then zz = Iz12.
A = L U. If elimination takes A to U without row exchanges, then the lower triangular L with multipliers eij (and eii = 1) brings U back to A.
Hilbert matrix hilb(n).
Entries HU = 1/(i + j -1) = Jd X i- 1 xj-1dx. Positive definite but extremely small Amin and large condition number: H is ill-conditioned.
A sequence of steps intended to approach the desired solution.
Kronecker product (tensor product) A ® B.
Blocks aij B, eigenvalues Ap(A)Aq(B).
Linear combination cv + d w or L C jV j.
Vector addition and scalar multiplication.
Linear transformation T.
Each vector V in the input space transforms to T (v) in the output space, and linearity requires T(cv + dw) = c T(v) + d T(w). Examples: Matrix multiplication A v, differentiation and integration in function space.
Normal equation AT Ax = ATb.
Gives the least squares solution to Ax = b if A has full rank n (independent columns). The equation says that (columns of A)·(b - Ax) = o.
If N NT = NT N, then N has orthonormal (complex) eigenvectors.
Nullspace matrix N.
The columns of N are the n - r special solutions to As = O.
Outer product uv T
= column times row = rank one matrix.
Rank one matrix A = uvT f=. O.
Column and row spaces = lines cu and cv.
Rayleigh quotient q (x) = X T Ax I x T x for symmetric A: Amin < q (x) < Amax.
Those extremes are reached at the eigenvectors x for Amin(A) and Amax(A).
Row picture of Ax = b.
Each equation gives a plane in Rn; the planes intersect at x.
Standard basis for Rn.
Columns of n by n identity matrix (written i ,j ,k in R3).
Symmetric factorizations A = LDLT and A = QAQT.
Signs in A = signs in D.
Vandermonde matrix V.
V c = b gives coefficients of p(x) = Co + ... + Cn_IXn- 1 with P(Xi) = bi. Vij = (Xi)j-I and det V = product of (Xk - Xi) for k > i.