[Shibi]

Hello to all,


I would like to ask for clarification on the LDU addressing in OpenFoam.



I have found online information where it is stated that the lowerAddr() keeps the row number of the lower() elements [blue color in the image bellow] and the column number of the upper() elements [red color in the image bellow], and that upperAddr() keeps the reverse (column of the lower() and row of the upper() ).

So, if I have a matrix like:



Matrix is from a 3x3 mesh generated with blockMesh.




When I print the lowerAddr() and upperAddr() they are:

lowerAddr() -> (0, 0, 1, 1, 2, 3, 3, 4, 4, 5, 6, 6, 7)

upperAddr() -> (1, 3, 2, 4, 5, 4, 6, 5, 7, 8, 7, 8)


From this I would assume that the lowerAddr() is keeping the information from the column in the lower() and the row in the upper().


Is this correct?


Additionally, can anyone explain what ownerStartAddr() is doing?