1.1 Special Form Matrices Band matrices:A satisfying ag =0 wheni->is called a band matrix. If a=0i>j+p,A has lower band p. ·lfa时=0，j>i+g,A has upper band g. A= o Upper/lower Heisenberg matrices H.- Hu= Tridiagonal matrices are upper and lower Heisenberg. 1 Special Matrices 4/601.1 Special Form Matrices Band matrices: A satisfying aij = 0 when|i − j| > k is called a band matrix. · If aij = 0 i > j + p, A has lower band p. · If aij = 0, j > i + q, A has upper band q. A =      ∗ · · · ∗ . . . ∗ . . . ∗ . . . ∗ . . . . . . . . . ∗ · · · ∗      Upper/lower Heisenberg matrices Hu =   ∗ ∗ · · · ∗ ∗ ∗ · · · ∗ . . . . . . . . . ∗ ∗   Hl =    ∗ ∗ ∗ ∗ . . . . . . . . . . . . ∗ ∗ ∗ · · · ∗    Tridiagonal matrices are upper and lower Heisenberg. 1 Special Matrices 4 / 60