dlag2s (l) - Linux Manuals

dlag2s: converts a DOUBLE PRECISION matrix, SA, to a SINGLE PRECISION matrix, A

NAME

DLAG2S - converts a DOUBLE PRECISION matrix, SA, to a SINGLE PRECISION matrix, A

SYNOPSIS

SUBROUTINE DLAG2S(
M, N, A, LDA, SA, LDSA, INFO )

    
INTEGER INFO, LDA, LDSA, M, N

    
REAL SA( LDSA, * )

    
DOUBLE PRECISION A( LDA, * )

PURPOSE

DLAG2S converts a DOUBLE PRECISION matrix, SA, to a SINGLE PRECISION matrix, A. RMAX is the overflow for the SINGLE PRECISION arithmetic
DLAG2S checks that all the entries of A are between -RMAX and RMAX. If not the convertion is aborted and a flag is raised. This is an auxiliary routine so there is no argument checking.

ARGUMENTS

M (input) INTEGER
The number of lines of the matrix A. M >= 0.
N (input) INTEGER
The number of columns of the matrix A. N >= 0.
A (input) DOUBLE PRECISION array, dimension (LDA,N)
On entry, the M-by-N coefficient matrix A.
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(1,M).
SA (output) REAL array, dimension (LDSA,N)
On exit, if INFO=0, the M-by-N coefficient matrix SA; if INFO>0, the content of SA is unspecified.
LDSA (input) INTEGER
The leading dimension of the array SA. LDSA >= max(1,M).
INFO (output) INTEGER
= 0: successful exit.
= 1: an entry of the matrix A is greater than the SINGLE PRECISION overflow threshold, in this case, the content of SA in exit is unspecified. ========= End of DLAG2S

Pages related to dlag2s

  • dlag2s (3)
  • dlag2 (l) - computes the eigenvalues of a 2 x 2 generalized eigenvalue problem A - w B, with scaling as necessary to avoid over-/underflow
  • dlags2 (l) - computes 2-by-2 orthogonal matrices U, V and Q, such that if ( UPPER ) then Uaq*A*Q = Uaq*( A1 A2 )*Q = ( x 0 ) ( 0 A3 ) ( x x ) and Vaq*B*Q = Vaq*( B1 B2 )*Q = ( x 0 ) ( 0 B3 ) ( x x ) or if ( .NOT.UPPER ) then Uaq*A*Q = Uaq*( A1 0 )*Q = ( x x ) ( A2 A3 ) ( 0 x ) and Vaq*B*Q = Vaq*( B1 0 )*Q = ( x x ) ( B2 B3 ) ( 0 x ) The rows of the transformed A and B are parallel, where U = ( CSU SNU ), V = ( CSV SNV ), Q = ( CSQ SNQ ) ( -SNU CSU ) ( -SNV CSV ) ( -SNQ CSQ ) Zaq denotes the transpose of Z
  • dlagtf (l) - factorizes the matrix (T - lambda*I), where T is an n by n tridiagonal matrix and lambda is a scalar, as T - lambda*I = PLU,
  • dlagtm (l) - performs a matrix-vector 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
  • dlagts (l) - may be used to solve one of the systems of equations (T - lambda*I)*x = y or (T - lambda*I)aq*x = y,
  • dlagv2 (l) - computes the Generalized Schur factorization of a real 2-by-2 matrix pencil (A,B) where B is upper triangular
  • dla_gbamv (l) - performs one of the matrix-vector operations y := alpha*abs(A)*abs(x) + beta*abs(y),