Matrix multiplication – HP 15c User Manual
Page 155
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Section 12: Calculating with Matrices 155
For ÷, the matrix specified in the X-register is replaced by its LU
decomposition. The ÷ function calculates X
–1
Y using a more direct
method than does ∕ and *, giving the result faster and with improved
accuracy.
Example: Using matrices A and B from the previous example, calculate
C = A
T
B.
17
9
7
5
3
1
9
5
4
3
2
1
and
B
A
Keystrokes
Display
l>
A
A
2
3
Recalls descriptor for matrix A.
l>
B
b
2
3
Recalls descriptor for matrix B
into X-register, moving matrix
A descriptor into Y-register.
´<
C
b
2
3
Designates matrix C as result
matrix.
´> 5
C
3
3
Calculates A
T
B and stores
result in matrix C, which is
redimensioned to 3×3.
The result, matrix C, is
168
90
66
95
51
37
73
39
29
C
.
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