HP MLIB User's Guide Vol. 1 7th Ed.

260 HP MLIB User’s Guide
SSPR2/DSPR2/CHPR2/ZHPR2 Rank-2 update
Upper triangular storage
If the upper triangle of A is
then A is packed column-by-column into an array ap as follows:
Upper triangular matrix element a
ij
is stored in array element ap(i+(j×(j−1))/2).
Lower triangular storage
If the lower triangle of A is
then A is packed column-by-column into an array ap as follows:
Lower triangular matrix element a
ij
is stored in array element
ap(i+((j−1)×(2n−j))/2).
11 12 13 14
22 23 24
33 34
44
k 12345678910
ap(k) 11122213233314243444
11
21 22
31 32 33
41 42 43 44
k 12345678910
ap(k) 11213141223242334344