GETRS - 5.2 English - 68552

AOCL API Guide (68552)

Document ID
68552
Release Date
2025-12-29
Version
5.2 English
template<typename T>
void getrs(char *trans, integer *n, integer *nrhs, T *a, integer *lda, integer *ipiv, T *b, integer *ldb, integer *info)#

GETRS solves a system of linear equations.

Purpose:

  GETRS solves a system of linear equations
     A * X = B  or  A**T * X = B
  with a general N-by-N matrix A using the LU factorization computed
  by GETRF.
Parameters:
  • TRANS[in]

    TRANS is CHARACTER*1

    Specifies the form of the system of equations:

    = ‘N’: A * X = B (No transpose)

    = ‘T’: A**T* X = B (Transpose)

    = ‘C’: A**T* X = B (Conjugate transpose = Transpose)
  • N[in]

    N is INTEGER

    The order of the matrix A. N >= 0.

  • NRHS[in]

    NRHS is INTEGER

    The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.

  • A[in]

    A is REAL array, dimension (LDA,N)

    The factors L and U from the factorization A = P*L*U as computed by GETRF.

  • LDA[in]

    LDA is INTEGER

    The leading dimension of the array A. LDA >= fla_max(1,N).

  • IPIV[in]

    IPIV is INTEGER array, dimension (N)

    The pivot indices from GETRF; for 1<=i<=N, row i of the matrix was interchanged with row IPIV(i).

  • B[inout]

    B is REAL array, dimension (LDB,NRHS)

    On entry, the right hand side matrix B. On exit, the solution matrix X.

  • LDB[in]

    LDB is INTEGER

    The leading dimension of the array B. LDB >= fla_max(1,N).

  • INFO[out]

    INFO is INTEGER

    = 0: successful exit

    < 0: if INFO = -i, the i-th argument had an illegal value