gttrs - gttrs: triangular solve using factor

Generated automatically by Doxygen for LAPACK from the source code. Version 3.12.0 Sun Jul 20 2025 01:40:05 gttrs(3)

subroutinecgttrs(charactertrans,integern,integernrhs,complex,dimension(*)dl,complex,dimension(*)d,complex,dimension(*)du,complex,dimension(*)du2,integer,dimension(*)ipiv,complex,dimension(ldb,*)b,integerldb,integerinfo)CGTTRSPurpose: CGTTRS solves one of the systems of equations A * X = B, A**T * X = B, or A**H * X = B, with a tridiagonal matrix A using the LU factorization computed by CGTTRF. ParametersTRANS 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**H * X = B (Conjugate transpose) N N is INTEGER The order of the matrix A. NRHS NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0. DL DL is COMPLEX array, dimension (N-1) The (n-1) multipliers that define the matrix L from the LU factorization of A. D D is COMPLEX array, dimension (N) The n diagonal elements of the upper triangular matrix U from the LU factorization of A. DU DU is COMPLEX array, dimension (N-1) The (n-1) elements of the first super-diagonal of U. DU2 DU2 is COMPLEX array, dimension (N-2) The (n-2) elements of the second super-diagonal of U. IPIV IPIV is INTEGER array, dimension (N) The pivot indices; for 1 <= i <= n, row i of the matrix was interchanged with row IPIV(i). IPIV(i) will always be either i or i+1; IPIV(i) = i indicates a row interchange was not required. B B is COMPLEX array, dimension (LDB,NRHS) On entry, the matrix of right hand side vectors B. On exit, B is overwritten by the solution vectors X. LDB LDB is INTEGER The leading dimension of the array B. LDB >= max(1,N). INFO INFO is INTEGER = 0: successful exit < 0: if INFO = -k, the k-th argument had an illegal value Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. subroutinedgttrs(charactertrans,integern,integernrhs,doubleprecision,dimension(*)dl,doubleprecision,dimension(*)d,doubleprecision,dimension(*)du,doubleprecision,dimension(*)du2,integer,dimension(*)ipiv,doubleprecision,dimension(ldb,*)b,integerldb,integerinfo)DGTTRSPurpose: DGTTRS solves one of the systems of equations A*X = B or A**T*X = B, with a tridiagonal matrix A using the LU factorization computed by DGTTRF. ParametersTRANS 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 N is INTEGER The order of the matrix A. NRHS NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0. DL DL is DOUBLE PRECISION array, dimension (N-1) The (n-1) multipliers that define the matrix L from the LU factorization of A. D D is DOUBLE PRECISION array, dimension (N) The n diagonal elements of the upper triangular matrix U from the LU factorization of A. DU DU is DOUBLE PRECISION array, dimension (N-1) The (n-1) elements of the first super-diagonal of U. DU2 DU2 is DOUBLE PRECISION array, dimension (N-2) The (n-2) elements of the second super-diagonal of U. IPIV IPIV is INTEGER array, dimension (N) The pivot indices; for 1 <= i <= n, row i of the matrix was interchanged with row IPIV(i). IPIV(i) will always be either i or i+1; IPIV(i) = i indicates a row interchange was not required. B B is DOUBLE PRECISION array, dimension (LDB,NRHS) On entry, the matrix of right hand side vectors B. On exit, B is overwritten by the solution vectors X. LDB LDB is INTEGER The leading dimension of the array B. LDB >= max(1,N). INFO INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. subroutinesgttrs(charactertrans,integern,integernrhs,real,dimension(*)dl,real,dimension(*)d,real,dimension(*)du,real,dimension(*)du2,integer,dimension(*)ipiv,real,dimension(ldb,*)b,integerldb,integerinfo)SGTTRSPurpose: SGTTRS solves one of the systems of equations A*X = B or A**T*X = B, with a tridiagonal matrix A using the LU factorization computed by SGTTRF. ParametersTRANS 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 N is INTEGER The order of the matrix A. NRHS NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0. DL DL is REAL array, dimension (N-1) The (n-1) multipliers that define the matrix L from the LU factorization of A. D D is REAL array, dimension (N) The n diagonal elements of the upper triangular matrix U from the LU factorization of A. DU DU is REAL array, dimension (N-1) The (n-1) elements of the first super-diagonal of U. DU2 DU2 is REAL array, dimension (N-2) The (n-2) elements of the second super-diagonal of U. IPIV IPIV is INTEGER array, dimension (N) The pivot indices; for 1 <= i <= n, row i of the matrix was interchanged with row IPIV(i). IPIV(i) will always be either i or i+1; IPIV(i) = i indicates a row interchange was not required. B B is REAL array, dimension (LDB,NRHS) On entry, the matrix of right hand side vectors B. On exit, B is overwritten by the solution vectors X. LDB LDB is INTEGER The leading dimension of the array B. LDB >= max(1,N). INFO INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. subroutinezgttrs(charactertrans,integern,integernrhs,complex*16,dimension(*)dl,complex*16,dimension(*)d,complex*16,dimension(*)du,complex*16,dimension(*)du2,integer,dimension(*)ipiv,complex*16,dimension(ldb,*)b,integerldb,integerinfo)ZGTTRSPurpose: ZGTTRS solves one of the systems of equations A * X = B, A**T * X = B, or A**H * X = B, with a tridiagonal matrix A using the LU factorization computed by ZGTTRF. ParametersTRANS 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**H * X = B (Conjugate transpose) N N is INTEGER The order of the matrix A. NRHS NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0. DL DL is COMPLEX*16 array, dimension (N-1) The (n-1) multipliers that define the matrix L from the LU factorization of A. D D is COMPLEX*16 array, dimension (N) The n diagonal elements of the upper triangular matrix U from the LU factorization of A. DU DU is COMPLEX*16 array, dimension (N-1) The (n-1) elements of the first super-diagonal of U. DU2 DU2 is COMPLEX*16 array, dimension (N-2) The (n-2) elements of the second super-diagonal of U. IPIV IPIV is INTEGER array, dimension (N) The pivot indices; for 1 <= i <= n, row i of the matrix was interchanged with row IPIV(i). IPIV(i) will always be either i or i+1; IPIV(i) = i indicates a row interchange was not required. B B is COMPLEX*16 array, dimension (LDB,NRHS) On entry, the matrix of right hand side vectors B. On exit, B is overwritten by the solution vectors X. LDB LDB is INTEGER The leading dimension of the array B. LDB >= max(1,N). INFO INFO is INTEGER = 0: successful exit < 0: if INFO = -k, the k-th argument had an illegal value Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd.

gttrs - gttrs: triangular solve using factor

Functions subroutine cgttrs (trans, n, nrhs, dl, d, du, du2, ipiv, b, ldb, info) CGTTRS subroutine dgttrs (trans, n, nrhs, dl, d, du, du2, ipiv, b, ldb, info) DGTTRS subroutine sgttrs (trans, n, nrhs, dl, d, du, du2, ipiv, b, ldb, info) SGTTRS subroutine zgttrs (trans, n, nrhs, dl, d, du, du2, ipiv, b, ldb, info) ZGTTRS