lagtm - lagtm: tridiagonal matrix-matrix multiply

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

subroutineclagtm(charactertrans,integern,integernrhs,realalpha,complex,dimension(*)dl,complex,dimension(*)d,complex,dimension(*)du,complex,dimension(ldx,*)x,integerldx,realbeta,complex,dimension(ldb,*)b,integerldb)CLAGTM performs a matrix-matrix product of the form C = αAB+βC, where A is a tridiagonal matrix, B and C are rectangular matrices, and α and β are scalars, which may be 0, 1, or -1. Purpose: CLAGTM performs a matrix-matrix product of the form B := alpha * A * X + beta * B where A is a tridiagonal matrix of order N, B and X are N by NRHS matrices, and alpha and beta are real scalars, each of which may be 0., 1., or -1. ParametersTRANS TRANS is CHARACTER*1 Specifies the operation applied to A. = 'N': No transpose, B := alpha * A * X + beta * B = 'T': Transpose, B := alpha * A**T * X + beta * B = 'C': Conjugate transpose, B := alpha * A**H * X + beta * B N N is INTEGER The order of the matrix A. N >= 0. NRHS NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrices X and B. ALPHA ALPHA is REAL The scalar alpha. ALPHA must be 0., 1., or -1.; otherwise, it is assumed to be 0. DL DL is COMPLEX array, dimension (N-1) The (n-1) sub-diagonal elements of T. D D is COMPLEX array, dimension (N) The diagonal elements of T. DU DU is COMPLEX array, dimension (N-1) The (n-1) super-diagonal elements of T. X X is COMPLEX array, dimension (LDX,NRHS) The N by NRHS matrix X. LDX LDX is INTEGER The leading dimension of the array X. LDX >= max(N,1). BETA BETA is REAL The scalar beta. BETA must be 0., 1., or -1.; otherwise, it is assumed to be 1. B B is COMPLEX array, dimension (LDB,NRHS) On entry, the N by NRHS matrix B. On exit, B is overwritten by the matrix expression B := alpha * A * X + beta * B. LDB LDB is INTEGER The leading dimension of the array B. LDB >= max(N,1). Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. subroutinedlagtm(charactertrans,integern,integernrhs,doubleprecisionalpha,doubleprecision,dimension(*)dl,doubleprecision,dimension(*)d,doubleprecision,dimension(*)du,doubleprecision,dimension(ldx,*)x,integerldx,doubleprecisionbeta,doubleprecision,dimension(ldb,*)b,integerldb)DLAGTM performs a matrix-matrix product of the form C = αAB+βC, where A is a tridiagonal matrix, B and C are rectangular matrices, and α and β are scalars, which may be 0, 1, or -1. Purpose: DLAGTM performs a matrix-matrix product of the form B := alpha * A * X + beta * B where A is a tridiagonal matrix of order N, B and X are N by NRHS matrices, and alpha and beta are real scalars, each of which may be 0., 1., or -1. ParametersTRANS TRANS is CHARACTER*1 Specifies the operation applied to A. = 'N': No transpose, B := alpha * A * X + beta * B = 'T': Transpose, B := alpha * A'* X + beta * B = 'C': Conjugate transpose = Transpose N N is INTEGER The order of the matrix A. N >= 0. NRHS NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrices X and B. ALPHA ALPHA is DOUBLE PRECISION The scalar alpha. ALPHA must be 0., 1., or -1.; otherwise, it is assumed to be 0. DL DL is DOUBLE PRECISION array, dimension (N-1) The (n-1) sub-diagonal elements of T. D D is DOUBLE PRECISION array, dimension (N) The diagonal elements of T. DU DU is DOUBLE PRECISION array, dimension (N-1) The (n-1) super-diagonal elements of T. X X is DOUBLE PRECISION array, dimension (LDX,NRHS) The N by NRHS matrix X. LDX LDX is INTEGER The leading dimension of the array X. LDX >= max(N,1). BETA BETA is DOUBLE PRECISION The scalar beta. BETA must be 0., 1., or -1.; otherwise, it is assumed to be 1. B B is DOUBLE PRECISION array, dimension (LDB,NRHS) On entry, the N by NRHS matrix B. On exit, B is overwritten by the matrix expression B := alpha * A * X + beta * B. LDB LDB is INTEGER The leading dimension of the array B. LDB >= max(N,1). Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. subroutineslagtm(charactertrans,integern,integernrhs,realalpha,real,dimension(*)dl,real,dimension(*)d,real,dimension(*)du,real,dimension(ldx,*)x,integerldx,realbeta,real,dimension(ldb,*)b,integerldb)SLAGTM performs a matrix-matrix product of the form C = αAB+βC, where A is a tridiagonal matrix, B and C are rectangular matrices, and α and β are scalars, which may be 0, 1, or -1. Purpose: SLAGTM performs a matrix-matrix product of the form B := alpha * A * X + beta * B where A is a tridiagonal matrix of order N, B and X are N by NRHS matrices, and alpha and beta are real scalars, each of which may be 0., 1., or -1. ParametersTRANS TRANS is CHARACTER*1 Specifies the operation applied to A. = 'N': No transpose, B := alpha * A * X + beta * B = 'T': Transpose, B := alpha * A'* X + beta * B = 'C': Conjugate transpose = Transpose N N is INTEGER The order of the matrix A. N >= 0. NRHS NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrices X and B. ALPHA ALPHA is REAL The scalar alpha. ALPHA must be 0., 1., or -1.; otherwise, it is assumed to be 0. DL DL is REAL array, dimension (N-1) The (n-1) sub-diagonal elements of T. D D is REAL array, dimension (N) The diagonal elements of T. DU DU is REAL array, dimension (N-1) The (n-1) super-diagonal elements of T. X X is REAL array, dimension (LDX,NRHS) The N by NRHS matrix X. LDX LDX is INTEGER The leading dimension of the array X. LDX >= max(N,1). BETA BETA is REAL The scalar beta. BETA must be 0., 1., or -1.; otherwise, it is assumed to be 1. B B is REAL array, dimension (LDB,NRHS) On entry, the N by NRHS matrix B. On exit, B is overwritten by the matrix expression B := alpha * A * X + beta * B. LDB LDB is INTEGER The leading dimension of the array B. LDB >= max(N,1). Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd. subroutinezlagtm(charactertrans,integern,integernrhs,doubleprecisionalpha,complex*16,dimension(*)dl,complex*16,dimension(*)d,complex*16,dimension(*)du,complex*16,dimension(ldx,*)x,integerldx,doubleprecisionbeta,complex*16,dimension(ldb,*)b,integerldb)ZLAGTM performs a matrix-matrix product of the form C = αAB+βC, where A is a tridiagonal matrix, B and C are rectangular matrices, and α and β are scalars, which may be 0, 1, or -1. Purpose: ZLAGTM performs a matrix-matrix product of the form B := alpha * A * X + beta * B where A is a tridiagonal matrix of order N, B and X are N by NRHS matrices, and alpha and beta are real scalars, each of which may be 0., 1., or -1. ParametersTRANS TRANS is CHARACTER*1 Specifies the operation applied to A. = 'N': No transpose, B := alpha * A * X + beta * B = 'T': Transpose, B := alpha * A**T * X + beta * B = 'C': Conjugate transpose, B := alpha * A**H * X + beta * B N N is INTEGER The order of the matrix A. N >= 0. NRHS NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrices X and B. ALPHA ALPHA is DOUBLE PRECISION The scalar alpha. ALPHA must be 0., 1., or -1.; otherwise, it is assumed to be 0. DL DL is COMPLEX*16 array, dimension (N-1) The (n-1) sub-diagonal elements of T. D D is COMPLEX*16 array, dimension (N) The diagonal elements of T. DU DU is COMPLEX*16 array, dimension (N-1) The (n-1) super-diagonal elements of T. X X is COMPLEX*16 array, dimension (LDX,NRHS) The N by NRHS matrix X. LDX LDX is INTEGER The leading dimension of the array X. LDX >= max(N,1). BETA BETA is DOUBLE PRECISION The scalar beta. BETA must be 0., 1., or -1.; otherwise, it is assumed to be 1. B B is COMPLEX*16 array, dimension (LDB,NRHS) On entry, the N by NRHS matrix B. On exit, B is overwritten by the matrix expression B := alpha * A * X + beta * B. LDB LDB is INTEGER The leading dimension of the array B. LDB >= max(N,1). Author Univ. of Tennessee Univ. of California Berkeley Univ. of Colorado Denver NAG Ltd.

lagtm - lagtm: tridiagonal matrix-matrix multiply

Functions subroutine clagtm (trans, n, nrhs, alpha, dl, d, du, x, ldx, beta, b, ldb) CLAGTM performs a matrix-matrix product of the form C = αAB+βC, where A is a tridiagonal matrix, B and C are rectangular matrices, and α and β are scalars, which may be 0, 1, or -1. subroutine dlagtm (trans, n, nrhs, alpha, dl, d, du, x, ldx, beta, b, ldb) DLAGTM performs a matrix-matrix product of the form C = αAB+βC, where A is a tridiagonal matrix, B and C are rectangular matrices, and α and β are scalars, which may be 0, 1, or -1. subroutine slagtm (trans, n, nrhs, alpha, dl, d, du, x, ldx, beta, b, ldb) SLAGTM performs a matrix-matrix product of the form C = αAB+βC, where A is a tridiagonal matrix, B and C are rectangular matrices, and α and β are scalars, which may be 0, 1, or -1. subroutine zlagtm (trans, n, nrhs, alpha, dl, d, du, x, ldx, beta, b, ldb) ZLAGTM performs a matrix-matrix product of the form C = αAB+βC, where A is a tridiagonal matrix, B and C are rectangular matrices, and α and β are scalars, which may be 0, 1, or -1.