CPTTS2(3S)CPTTS2(3S)NAME
CPTTS2 - solve a tridiagonal system of the form A * X = B using the
factorization A = U'*D*U or A = L*D*L' computed by CPTTRF
SYNOPSIS
SUBROUTINE CPTTS2( IUPLO, N, NRHS, D, E, B, LDB )
INTEGER IUPLO, LDB, N, NRHS
REAL D( * )
COMPLEX B( LDB, * ), E( * )
IMPLEMENTATION
These routines are part of the SCSL Scientific Library and can be loaded
using either the -lscs or the -lscs_mp option. The -lscs_mp option
directs the linker to use the multi-processor version of the library.
When linking to SCSL with -lscs or -lscs_mp, the default integer size is
4 bytes (32 bits). Another version of SCSL is available in which integers
are 8 bytes (64 bits). This version allows the user access to larger
memory sizes and helps when porting legacy Cray codes. It can be loaded
by using the -lscs_i8 option or the -lscs_i8_mp option. A program may use
only one of the two versions; 4-byte integer and 8-byte integer library
calls cannot be mixed.
PURPOSE
CPTTS2 solves a tridiagonal system of the form A * X = B using the
factorization A = U'*D*U or A = L*D*L' computed by CPTTRF. D is a
diagonal matrix specified in the vector D, U (or L) is a unit bidiagonal
matrix whose superdiagonal (subdiagonal) is specified in the vector E,
and X and B are N by NRHS matrices.
ARGUMENTS
IUPLO (input) INTEGER
Specifies the form of the factorization and whether the vector E
is the superdiagonal of the upper bidiagonal factor U or the
subdiagonal of the lower bidiagonal factor L. = 1: A = U'*D*U,
E is the superdiagonal of U
= 0: A = L*D*L', E is the subdiagonal of L
N (input) INTEGER
The order of the tridiagonal matrix A. N >= 0.
NRHS (input) INTEGER
The number of right hand sides, i.e., the number of columns of
the matrix B. NRHS >= 0.
D (input) REAL array, dimension (N)
The n diagonal elements of the diagonal matrix D from the
factorization A = U'*D*U or A = L*D*L'.
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CPTTS2(3S)CPTTS2(3S)
E (input) COMPLEX array, dimension (N-1)
If IUPLO = 1, the (n-1) superdiagonal elements of the unit
bidiagonal factor U from the factorization A = U'*D*U. If IUPLO
= 0, the (n-1) subdiagonal elements of the unit bidiagonal factor
L from the factorization A = L*D*L'.
B (input/output) REAL array, dimension (LDB,NRHS)
On entry, the right hand side vectors B for the system of linear
equations. On exit, the solution vectors, X.
LDB (input) INTEGER
The leading dimension of the array B. LDB >= max(1,N).
SEE ALSOINTRO_LAPACK(3S), INTRO_SCSL(3S)
This man page is available only online.
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