What you need to know to use these subprograms

Table 4-15 SKY Format Matrix

val=

11

21

22

32

33

42

0

44

51

0

0

54

55

pntr=

1

2

4

6

9

14

 

 

 

 

 

 

 

Block entry formats

All block entry formats can be used to represent matrices with fixed square block size. The Variable Block Compressed Sparse Row format can also be used for matrices with variable block sizes.

BCO - Block coordinate. Given a sparse block matrix A formed by mb-by-kbsquare blocks of size lb-by-lbeach, the block coordinate format represents the bnnz nonzero block entries using the same variables as in the COO format.

Each nonzero dense block is stored in column major order. Three arrays are required for the BCO representation:

•val( lb, lb,*) - Scalar matrix of dimension lb-by-lb-by-bnnzcontaining the nonzero lb-by-lbblocks.

•bindx(*) - Integer array of length bnnz containing block row indices such that bindx(i) corresponds to the block row index of the matrix block val( :, :, i).

•bjndx(*) - Integer array of length bnnz containing block column indices such that bjndx(i) corresponds to the block column index of val( :, :, i).

Consider, for example, the 4 x 6 matrix:

Table 4-16

4 x 6 Matrix

 

 

 

 

 

11

12

0

0

15

16

 

21

22

0

0

25

26

 

0

0

33

0

35

36

 

0

0

43

44

0

46

432HP MLIB User’s Guide