Visible to Intel only — GUID: GUID-4A257C32-0C27-4C64-B11F-5E9BB079F44C
Visible to Intel only — GUID: GUID-4A257C32-0C27-4C64-B11F-5E9BB079F44C
?la_syrpvgrw
Computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric indefinite matrix.
Syntax
call sla_syrpvgrw( uplo, n, info, a, lda, af, ldaf, ipiv, work )
call dla_syrpvgrw( uplo, n, info, a, lda, af, ldaf, ipiv, work )
call cla_syrpvgrw( uplo, n, info, a, lda, af, ldaf, ipiv, work )
call zla_syrpvgrw( uplo, n, info, a, lda, af, ldaf, ipiv, work )
Include Files
- mkl.fi
Description
The ?la_syrpvgrw routine computes the reciprocal pivot growth factor norm(A)/norm(U). The max absolute element norm is used. If this is much less than 1, the stability of the LU factorization of the equilibrated matrix A could be poor. This also means that the solution X, estimated condition numbers, and error bounds could be unreliable.
Input Parameters
uplo |
CHARACTER*1. Must be 'U' or 'L'. Specifies the triangle of A to store: If uplo = 'U', the upper triangle of A is stored, If uplo = 'L', the lower triangle of A is stored. |
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n |
INTEGER. The number of linear equations, the order of the matrix A; n≥ 0. |
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info |
INTEGER. The value of INFO returned from ?sytrf, that is, the pivot in column info is exactly 0. |
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a, af |
REAL for sla_syrpvgrw DOUBLE PRECISION for dla_syrpvgrw COMPLEX for cla_syrpvgrw DOUBLE COMPLEX for zla_syrpvgrw. Arrays: a(lda,*), af(ldaf,*). The array a contains the input n-by-n matrix A. The second dimension of a must be at least max(1,n). The array af contains the block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by ?sytrf. |
The second dimension of af must be at least max(1,n). |
lda |
INTEGER. The leading dimension of a; lda≥ max(1,n). |
|
ldaf |
INTEGER. The leading dimension of af; ldaf≥ max(1,n). |
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ipiv |
INTEGER. Array, DIMENSIONn. Details of the interchanges and the block structure of D as determined by ?sytrf. |
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work |
REAL for sla_syrpvgrw and cla_syrpvgrw DOUBLE PRECISION for dla_syrpvgrw and zla_syrpvgrw. Workspace array, dimension 2*n. |