• NAME
• SYNOPSIS
• F95 INTERFACE
• C INTERFACE
• PURPOSE
• ARGUMENTS

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)
  COMPLEX E(*), B(LDB,*)
  INTEGER IUPLO, N, NRHS, LDB
  REAL D(*)

  SUBROUTINE CPTTS2_64( IUPLO, N, NRHS, D, E, B, LDB)
  COMPLEX E(*), B(LDB,*)
  INTEGER*8 IUPLO, N, NRHS, LDB
  REAL D(*)

F95 INTERFACE

  SUBROUTINE CPTTS2( IUPLO, N, NRHS, D, E, B, LDB)
  COMPLEX, DIMENSION(:) :: E
  COMPLEX, DIMENSION(:,:) :: B
  INTEGER :: IUPLO, N, NRHS, LDB
  REAL, DIMENSION(:) :: D

  SUBROUTINE CPTTS2_64( IUPLO, N, NRHS, D, E, B, LDB)
  COMPLEX, DIMENSION(:) :: E
  COMPLEX, DIMENSION(:,:) :: B
  INTEGER(8) :: IUPLO, N, NRHS, LDB
  REAL, DIMENSION(:) :: D

C INTERFACE

#include <sunperf.h>

void cptts2(int iuplo, int n, int nrhs, float *d, complex *e, complex *b, int ldb);

void cptts2_64(long iuplo, long n, long nrhs, float *d, complex *e, complex *b, long ldb);

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

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

• D (input)
  The n diagonal elements of the diagonal matrix D from the factorization A = U'*D*U or A = L*D*L'.

• E (input)
  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)
  On entry, the right hand side vectors B for the system of linear equations. On exit, the solution vectors, X.

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