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## Array Descriptor for the Matrix of Right-Hand-Side Vectors

The array descriptor DESC_ whose type is defined as DESC_(DTYPE_)=502 , is an integer array of length 7. This descriptor type is used in the ScaLAPACK narrow band routines and tridiagonal routines to specify the block-row distribution of a global array containing the right-hand-side vectors over a one-dimensional process grid. In the narrow band and tridiagonal routines, a one-dimensional block-column distribution is specified for the coefficient matrix . The matrix of right-hand-side vectors however must be distributed over a one-dimensional process grid according to a block-row data distribution scheme. Refer to section 4.4.1 for further details on block data distribution.

Let us now assume that we have an array descriptor DESCB for a block-row distributed matrix B. For readability of the code, we have associated symbolic names with the descriptor entries.

Table 4.12: Content of the array descriptor for right-hand-side dense matrices for narrow band and tridiagonal solvers

For a detailed description of LOC() notation, please refer to section 4.4.2.