CGBSV man page on Oracle

Printed from

cgbsv.f(3)			    LAPACK			    cgbsv.f(3)

       cgbsv.f -

       subroutine cgbsv (N, KL, KU, NRHS, AB, LDAB, IPIV, B, LDB, INFO)
	    CGBSV computes the solution to system of linear equations A * X =
	   B for GB matrices (simple driver)

Function/Subroutine Documentation
   subroutine cgbsv (integerN, integerKL, integerKU, integerNRHS, complex,
       dimension( ldab, * )AB, integerLDAB, integer, dimension( * )IPIV,
       complex, dimension( ldb, * )B, integerLDB, integerINFO)
	CGBSV computes the solution to system of linear equations A * X = B
       for GB matrices (simple driver)


	    CGBSV computes the solution to a complex system of linear equations
	    A * X = B, where A is a band matrix of order N with KL subdiagonals
	    and KU superdiagonals, and X and B are N-by-NRHS matrices.

	    The LU decomposition with partial pivoting and row interchanges is
	    used to factor A as A = L * U, where L is a product of permutation
	    and unit lower triangular matrices with KL subdiagonals, and U is
	    upper triangular with KL+KU superdiagonals.	 The factored form of A
	    is then used to solve the system of equations A * X = B.


		     N is INTEGER
		     The number of linear equations, i.e., the order of the
		     matrix A.	N >= 0.


		     KL is INTEGER
		     The number of subdiagonals within the band of A.  KL >= 0.


		     KU is INTEGER
		     The number of superdiagonals within the band of A.	 KU >= 0.


		     NRHS is INTEGER
		     The number of right hand sides, i.e., the number of columns
		     of the matrix B.  NRHS >= 0.


		     AB is COMPLEX array, dimension (LDAB,N)
		     On entry, the matrix A in band storage, in rows KL+1 to
		     2*KL+KU+1; rows 1 to KL of the array need not be set.
		     The j-th column of A is stored in the j-th column of the
		     array AB as follows:
		     AB(KL+KU+1+i-j,j) = A(i,j) for max(1,j-KU)<=i<=min(N,j+KL)
		     On exit, details of the factorization: U is stored as an
		     upper triangular band matrix with KL+KU superdiagonals in
		     rows 1 to KL+KU+1, and the multipliers used during the
		     factorization are stored in rows KL+KU+2 to 2*KL+KU+1.
		     See below for further details.


		     LDAB is INTEGER
		     The leading dimension of the array AB.  LDAB >= 2*KL+KU+1.


		     IPIV is INTEGER array, dimension (N)
		     The pivot indices that define the permutation matrix P;
		     row i of the matrix was interchanged with row IPIV(i).


		     B is COMPLEX array, dimension (LDB,NRHS)
		     On entry, the N-by-NRHS right hand side matrix B.
		     On exit, if INFO = 0, the N-by-NRHS solution matrix X.


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


		     INFO is INTEGER
		     = 0:  successful exit
		     < 0:  if INFO = -i, the i-th argument had an illegal value
		     > 0:  if INFO = i, U(i,i) is exactly zero.	 The factorization
			   has been completed, but the factor U is exactly
			   singular, and the solution has not been computed.

	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

	   November 2011

       Further Details:

	     The band storage scheme is illustrated by the following example, when
	     M = N = 6, KL = 2, KU = 1:

	     On entry:			     On exit:

		 *    *	   *	+    +	  +	  *    *    *	u14  u25  u36
		 *    *	   +	+    +	  +	  *    *   u13	u24  u35  u46
		 *   a12  a23  a34  a45	 a56	  *   u12  u23	u34  u45  u56
		a11  a22  a33  a44  a55	 a66	 u11  u22  u33	u44  u55  u66
		a21  a32  a43  a54  a65	  *	 m21  m32  m43	m54  m65   *
		a31  a42  a53  a64   *	  *	 m31  m42  m53	m64   *	   *

	     Array elements marked * are not used by the routine; elements marked
	     + need not be set on entry, but are required by the routine to store
	     elements of U because of fill-in resulting from the row interchanges.

       Definition at line 163 of file cgbsv.f.

       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2			Tue Sep 25 2012			    cgbsv.f(3)

List of man pages available for Oracle

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
Vote for polarhome
Free Shell Accounts :: the biggest list on the net