
NAMEzungtr.f SYNOPSISFunctions/Subroutinessubroutine zungtr (UPLO, N, A, LDA, TAU, WORK, LWORK, INFO) Function/Subroutine Documentationsubroutine zungtr (characterUPLO, integerN, complex*16, dimension( lda, * )A, integerLDA, complex*16, dimension( * )TAU, complex*16, dimension( * )WORK, integerLWORK, integerINFO)ZUNGTR Purpose:ZUNGTR generates a complex unitary matrix Q which is defined as the product of n1 elementary reflectors of order N, as returned by ZHETRD: if UPLO = 'U', Q = H(n1) . . . H(2) H(1), if UPLO = 'L', Q = H(1) H(2) . . . H(n1). UPLO
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UPLO is CHARACTER*1 = 'U': Upper triangle of A contains elementary reflectors from ZHETRD; = 'L': Lower triangle of A contains elementary reflectors from ZHETRD.N N is INTEGER The order of the matrix Q. N >= 0.A A is COMPLEX*16 array, dimension (LDA,N) On entry, the vectors which define the elementary reflectors, as returned by ZHETRD. On exit, the NbyN unitary matrix Q.LDA LDA is INTEGER The leading dimension of the array A. LDA >= N.TAU TAU is COMPLEX*16 array, dimension (N1) TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by ZHETRD.WORK WORK is COMPLEX*16 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 >= N1. For optimum performance LWORK >= (N1)*NB, where NB is the optimal blocksize. If LWORK = 1, then a workspace query is assumed; the routine only calculates the optimal size of the WORK array, returns this value as the first entry of the WORK array, and no error message related to LWORK is issued by XERBLA.INFO INFO is INTEGER = 0: successful exit < 0: if INFO = i, the ith argument had an illegal value Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
November 2011
Definition at line 124 of file zungtr.f.
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