# ignoreRowsAndColumns An array that contains row and column indices to ignore. ``` var ignoreRowsAndColumns: UnsafeMutablePointer? ``` ## Discussion If this array isn’t `nil`, [`ignoreRowsAndColumns`](/documentation/Accelerate/SparseSymbolicFactorOptions/ignoreRowsAndColumns) provides a list of rows and columns to ignore. Terminate [`ignoreRowsAndColumns`](/documentation/Accelerate/SparseSymbolicFactorOptions/ignoreRowsAndColumns) with a negative index. The row and column indices are for the actual matrix, not its block structure, so `0` indicates the first row, not the first `blockSize` rows. In the symmetric case (Cholesky, *LDLᵀ*), each entry indicates that the system needs to ignore the matching row and column. In the unsymmetric case (QR, Cholesky *AᵀA*), consider the matrix, `A`, given the value `m`, with one of the following definitions: - `m = A.structure.rowCount * A.blockSize` if `A` isn’t a transposed matrix - `m = A.structure.columnCount * A.blockSize` if `A` is a transposed matrix In this case, an index less than `m` indicates that the system needs to ignore row `m`. An index `i`, greater than `m`, indicates that the system needs to ignore columns `i - m`. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)