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(a) For the matrix find A = [-1 3 2 -4] find i. the matrix 1-norm ii. the matrix

ID: 3123958 • Letter: #

Question

(a) For the matrix find A = [-1 3 2 -4] find i. the matrix 1-norm ii. the matrix infinity-norm iii. the Frobenius norm iv. the condition number, Use the matrix 1-norm for this. (b) For the matrix B = [1 2 2 4] find i. the matrix 1-norm ii. the matrix infinity norm iii. the Frobenius norm iv. the condition number. Use the matrix 1-norm for this (c) For the matrix C = [5 0 0 0 10 0 0 0 20] find i. the matrix 1-norm ii. the matrix infinity-norm iii. the Frobenius norm. iv the condition number. Use the matrix 1-norm for this.

Explanation / Answer

1. a.)

(i)

A = -1 2

3 -4

The absolute column sums of A are |-1| + 3 = 4 and 2 + | 4| = 6. The larger of these
is 6 and therefore A1 = 6.

(ii)

The absolute row sums of A are |-1 |+ 2 = 3 and 3 + | 4| = 7. The larger of these is 7
and therefore A = 7.

(iii)

the frobinius norm is

underoot (|-1|2 + |2|2 + |3|2 + |-4|2 ) = underoot(30) = 5.47

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b.) matrix B = 1 2

2 4

(i) The absolute column sums of B are 1 + 2 = 3 and 2 + 4 = 6. The larger of these
is 6 and therefore B1 = 6.

(ii) The absolute row sums of B are 1 + 2 = 3 and 2+ 4 = 6. The larger of these is 6
and therefore B = 6

(iii) the frobinius norm is

underoot( |1|2 + |2|2 + |2|2 + |4|2 )=underoot(25) = 5

c.)

matrix C = 5 0 0

0 10 0

0 0 20.

(i) The absolute column sums of C are 5+0+0 = 5 and 0 + 10 + 0 = 10and 0 + 0 + 20 = 20. The larger of these
is 20 and therefore C1 = 20

(ii).The absolute row sums of C are 5+0+0= 5 and 0+10+0 =10 and 0 + 0 + 20 =20 The larger of these is 20
and therefore C = 20

(iii) the frobinius norm is

underoot( |5|2 + |0|2 + |0|2 + |0|2 + |10|2 + |0|2 + |0|2 + |0|2 + |20|2 ) = underoot(525) =22.91