CentOS 7.0 - man page for cgesdd (centos section 3)

Linux & Unix Commands - Search Man Pages

Man Page or Keyword Search:   man
Select Man Page Set:       apropos Keyword Search (sections above)


cgesdd.f(3)				      LAPACK				      cgesdd.f(3)

NAME
       cgesdd.f -

SYNOPSIS
   Functions/Subroutines
       subroutine cgesdd (JOBZ, M, N, A, LDA, S, U, LDU, VT, LDVT, WORK, LWORK, RWORK, IWORK,
	   INFO)
	   CGESDD

Function/Subroutine Documentation
   subroutine cgesdd (characterJOBZ, integerM, integerN, complex, dimension( lda, * )A,
       integerLDA, real, dimension( * )S, complex, dimension( ldu, * )U, integerLDU, complex,
       dimension( ldvt, * )VT, integerLDVT, complex, dimension( * )WORK, integerLWORK, real,
       dimension( * )RWORK, integer, dimension( * )IWORK, integerINFO)
       CGESDD

       Purpose:

	    CGESDD computes the singular value decomposition (SVD) of a complex
	    M-by-N matrix A, optionally computing the left and/or right singular
	    vectors, by using divide-and-conquer method. The SVD is written

		 A = U * SIGMA * conjugate-transpose(V)

	    where SIGMA is an M-by-N matrix which is zero except for its
	    min(m,n) diagonal elements, U is an M-by-M unitary matrix, and
	    V is an N-by-N unitary matrix.  The diagonal elements of SIGMA
	    are the singular values of A; they are real and non-negative, and
	    are returned in descending order.  The first min(m,n) columns of
	    U and V are the left and right singular vectors of A.

	    Note that the routine returns VT = V**H, not V.

	    The divide and conquer algorithm makes very mild assumptions about
	    floating point arithmetic. It will work on machines with a guard
	    digit in add/subtract, or on those binary machines without guard
	    digits which subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or
	    Cray-2. It could conceivably fail on hexadecimal or decimal machines
	    without guard digits, but we know of none.

       Parameters:
	   JOBZ

		     JOBZ is CHARACTER*1
		     Specifies options for computing all or part of the matrix U:
		     = 'A':  all M columns of U and all N rows of V**H are
			     returned in the arrays U and VT;
		     = 'S':  the first min(M,N) columns of U and the first
			     min(M,N) rows of V**H are returned in the arrays U
			     and VT;
		     = 'O':  If M >= N, the first N columns of U are overwritten
			     in the array A and all rows of V**H are returned in
			     the array VT;
			     otherwise, all columns of U are returned in the
			     array U and the first M rows of V**H are overwritten
			     in the array A;
		     = 'N':  no columns of U or rows of V**H are computed.

	   M

		     M is INTEGER
		     The number of rows of the input matrix A.	M >= 0.

	   N

		     N is INTEGER
		     The number of columns of the input matrix A.  N >= 0.

	   A

		     A is COMPLEX array, dimension (LDA,N)
		     On entry, the M-by-N matrix A.
		     On exit,
		     if JOBZ = 'O',  A is overwritten with the first N columns
				     of U (the left singular vectors, stored
				     columnwise) if M >= N;
				     A is overwritten with the first M rows
				     of V**H (the right singular vectors, stored
				     rowwise) otherwise.
		     if JOBZ .ne. 'O', the contents of A are destroyed.

	   LDA

		     LDA is INTEGER
		     The leading dimension of the array A.  LDA >= max(1,M).

	   S

		     S is REAL array, dimension (min(M,N))
		     The singular values of A, sorted so that S(i) >= S(i+1).

	   U

		     U is COMPLEX array, dimension (LDU,UCOL)
		     UCOL = M if JOBZ = 'A' or JOBZ = 'O' and M < N;
		     UCOL = min(M,N) if JOBZ = 'S'.
		     If JOBZ = 'A' or JOBZ = 'O' and M < N, U contains the M-by-M
		     unitary matrix U;
		     if JOBZ = 'S', U contains the first min(M,N) columns of U
		     (the left singular vectors, stored columnwise);
		     if JOBZ = 'O' and M >= N, or JOBZ = 'N', U is not referenced.

	   LDU

		     LDU is INTEGER
		     The leading dimension of the array U.  LDU >= 1; if
		     JOBZ = 'S' or 'A' or JOBZ = 'O' and M < N, LDU >= M.

	   VT

		     VT is COMPLEX array, dimension (LDVT,N)
		     If JOBZ = 'A' or JOBZ = 'O' and M >= N, VT contains the
		     N-by-N unitary matrix V**H;
		     if JOBZ = 'S', VT contains the first min(M,N) rows of
		     V**H (the right singular vectors, stored rowwise);
		     if JOBZ = 'O' and M < N, or JOBZ = 'N', VT is not referenced.

	   LDVT

		     LDVT is INTEGER
		     The leading dimension of the array VT.  LDVT >= 1; if
		     JOBZ = 'A' or JOBZ = 'O' and M >= N, LDVT >= N;
		     if JOBZ = 'S', LDVT >= min(M,N).

	   WORK

		     WORK is COMPLEX array, dimension (MAX(1,LWORK))
		     On exit, if INFO = 0, WORK(1) returns the optimal LWORK.

	   LWORK

		     LWORK is INTEGER
		     The dimension of the array WORK. LWORK >= 1.
		     if JOBZ = 'N', LWORK >= 2*min(M,N)+max(M,N).
		     if JOBZ = 'O',
			   LWORK >= 2*min(M,N)*min(M,N)+2*min(M,N)+max(M,N).
		     if JOBZ = 'S' or 'A',
			   LWORK >= min(M,N)*min(M,N)+2*min(M,N)+max(M,N).
		     For good performance, LWORK should generally be larger.

		     If LWORK = -1, a workspace query is assumed.  The optimal
		     size for the WORK array is calculated and stored in WORK(1),
		     and no other work except argument checking is performed.

	   RWORK

		     RWORK is REAL array, dimension (MAX(1,LRWORK))
		     If JOBZ = 'N', LRWORK >= 5*min(M,N).
		     Otherwise,
		     LRWORK >= min(M,N)*max(5*min(M,N)+7,2*max(M,N)+2*min(M,N)+1)

	   IWORK

		     IWORK is INTEGER array, dimension (8*min(M,N))

	   INFO

		     INFO is INTEGER
		     = 0:  successful exit.
		     < 0:  if INFO = -i, the i-th argument had an illegal value.
		     > 0:  The updating process of SBDSDC did not converge.

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   November 2011

       Contributors:
	   Ming Gu and Huan Ren, Computer Science Division, University of California at Berkeley,
	   USA

       Definition at line 222 of file cgesdd.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2				 Tue Sep 25 2012			      cgesdd.f(3)
Unix & Linux Commands & Man Pages : ©2000 - 2018 Unix and Linux Forums


All times are GMT -4. The time now is 10:51 AM.

Unix & Linux Forums Content Copyright©1993-2018. All Rights Reserved.
×
UNIX.COM Login
Username:
Password:  
Show Password





Not a Forum Member?
Forgot Password?