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

NAME

cptsv - compute the solution to a complex system of linear equations A*X = B, where A is an N-by-N Hermitian positive definite tridiagonal matrix, and X and B are N-by-NRHS matrices.

SYNOPSIS

  SUBROUTINE CPTSV( N, NRHS, DIAG, SUB, B, LDB, INFO)
  COMPLEX SUB(*), B(LDB,*)
  INTEGER N, NRHS, LDB, INFO
  REAL DIAG(*)

  SUBROUTINE CPTSV_64( N, NRHS, DIAG, SUB, B, LDB, INFO)
  COMPLEX SUB(*), B(LDB,*)
  INTEGER*8 N, NRHS, LDB, INFO
  REAL DIAG(*)

F95 INTERFACE

  SUBROUTINE PTSV( [N], [NRHS], DIAG, SUB, B, [LDB], [INFO])
  COMPLEX, DIMENSION(:) :: SUB
  COMPLEX, DIMENSION(:,:) :: B
  INTEGER :: N, NRHS, LDB, INFO
  REAL, DIMENSION(:) :: DIAG

  SUBROUTINE PTSV_64( [N], [NRHS], DIAG, SUB, B, [LDB], [INFO])
  COMPLEX, DIMENSION(:) :: SUB
  COMPLEX, DIMENSION(:,:) :: B
  INTEGER(8) :: N, NRHS, LDB, INFO
  REAL, DIMENSION(:) :: DIAG

C INTERFACE

#include <sunperf.h>

void cptsv(int n, int nrhs, float *diag, complex *sub, complex *b, int ldb, int *info);

void cptsv_64(long n, long nrhs, float *diag, complex *sub, complex *b, long ldb, long *info);

PURPOSE

cptsv computes the solution to a complex system of linear equations A*X = B, where A is an N-by-N Hermitian positive definite tridiagonal matrix, and X and B are N-by-NRHS matrices.

A is factored as A = L*D*L**H, and the factored form of A is then used to solve the system of equations.

ARGUMENTS

• N (input)
  The order of the matrix A. N > = 0.

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

• DIAG (input/output)
  On entry, the n diagonal elements of the tridiagonal matrix A. On exit, the n diagonal elements of the diagonal matrix DIAG from the factorization A = L*DIAG*L**H.

• SUB (input/output)
  On entry, the (n-1) subdiagonal elements of the tridiagonal matrix A. On exit, the (n-1) subdiagonal elements of the unit bidiagonal factor L from the L*DIAG*L**H factorization of A. SUB can also be regarded as the superdiagonal of the unit bidiagonal factor U from the U**H*DIAG*U factorization of A.

• B (input/output)
  On entry, the N-by-NRHS right hand side matrix B. On exit, if INFO = 0, the N-by-NRHS solution matrix X.

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

• INFO (output)
  

   = 0:  successful exit

   < 0:  if INFO  = -i, the i-th argument had an illegal value

   > 0:  if INFO  = i, the leading minor of order i is not
  positive definite, and the solution has not been
  computed.  The factorization has not been completed
  unless i  = N.