User Manual

Section 4: Using Matrix Operations 89
For example, let matrix A be














112
111
21103
40
A
.
The HP-15C correctly calculates A
−1
to 10-digit accuracy as















121
243
132
1
A
.
Now let













20
20
20
1000
0100
0010
RL
so that














4040
4040
10102
10101
213
E
.
E is very near a singular matrix











002
001
213
S
and ||E – S|| / ||E|| = ⅓ × 10
–40
. This means that K(S) ≥ 3 × 10
40
, so it's not surprising that the
calculated E
–1
















99
99
1011
10142.210284.407155.0
10284.410569.88569.0
1011067.6
1
E
is far from the true value
















4040
4040
40
101021
1021043
13102
1
E