HP 15c User Manual

Page 89

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Section 4: Using Matrix Operations

89

For example, let matrix A be

1

1

2

1

1

1

2

1

10

3

40

A

.

The HP-15C correctly calculates A

−1

to 10-digit accuracy as

1

2

1

2

4

3

1

3

2

1

A

.

Now let

20

20

20

10

0

0

0

10

0

0

0

10

R

L

so that

40

40

40

40

10

10

2

10

10

1

2

1

3

E

.

E is very near a singular matrix

0

0

2

0

0

1

2

1

3

S

and ||ES|| / ||E|| = ⅓ × 10

–40

. This means that K(S) ≥ 3 × 10

40

, so it's not surprising that the

calculated E

–1

9

9

9

9

10

11

10

142

.

2

10

284

.

4

07155

.

0

10

284

.

4

10

569

.

8

8569

.

0

10

1

10

67

.

6

1

E

is far from the true value

40

40

40

40

40

10

10

2

1

10

2

10

4

3

1

3

10

2

1

E

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