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◆ zunmhr()
| void zunmhr |
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char |
side, |
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char |
trans, |
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int |
m, |
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int |
n, |
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int |
ilo, |
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int |
ihi, |
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int |
lda, |
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doublecomplex |
a[], |
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doublecomplex |
tau[], |
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int |
ldc, |
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doublecomplex |
c[], |
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doublecomplex |
work[], |
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int |
lwork, |
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int * |
info |
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Multiplies by a complex transform matrix to Hessenberg form
- Purpose
- This routine overwrites the general complex m x n matrix C with
side = 'L' side = 'R'
trans = 'N': Q * C C * Q
trans = 'T': Q^H * C C * Q^H
where Q is a complex unitary matrix of order nq, with nq = m if side = 'L' and nq = n if side = 'R'. Q is defined as the product of ihi-ilo elementary reflectors, as returned by zgehrd: Q = H(ilo) H(ilo+1) . . . H(ihi-1).
- Parameters
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| [in] | side | = 'L': Apply Q or Q^H from the Left.
= 'R': Apply Q or Q^H from the Right. |
| [in] | trans | = 'N': No transpose, apply Q.
= 'C': Conjugate transpose, apply Q^H. |
| [in] | m | Number of rows of the matrix C. (m >= 0) (If m = 0, returns without computation) |
| [in] | n | Order of the matrix A. (n >= 0) (If n = 0, returns without computation) |
| [in] | ilo | |
| [in] | ihi | ilo and ihi must have the same values as in the previous call of zgehrd. Q is equal to the unit matrix except in the submatrix Q(ilo+1〜ihi, ilo+1〜ihi).
If side = 'L', then 1 <= ilo <= ihi <= m, if m > 0, and ilo = 1 and ihi = 0, if m = 0.
if side = 'R', then 1 <= ilo <= ihi <= n, if n > 0, and ilo = 1 and ihi = 0, if n = 0. |
| [in] | lda | Leading dimension of the two dimensional array a[][]. (lda >= max(1, m) if side = 'L', lda >= max(1, n) if side = 'R') |
| [in] | a[][] | Array a[la][lda] (la >= m if side = 'L', la >= n if side = 'R')
The vectors which define the elementary reflectors, as returned by zgehrd. |
| [in] | tau[] | Array tau[ltau] (ltau >= m - 1 if side = 'L', ltau >= n - 1 if side = 'R')
tau[i] must contain the scalar factor of the elementary reflector H(i), as returned by zgehrd. |
| [in] | ldc | Leading dimension of the two dimensional array c[][]. (ldc >= max(1, m)) |
| [in,out] | c[][] | Array c[lc][ldc] (lc >= n)
[in] The m x n matrix C.
[out] C is overwritten by Q*C or Q^H*C or C*Q^H or C*Q. |
| [out] | work[] | Array work[lwork]
Work array.
On exit, if info = 0, work[0] returns the optimal lwork. |
| [in] | lwork | The size of work[]. (lwork >= max(1, n) if side = 'L', lwork >= max(1, m) if side = 'R')
For optimum performance lwork >= n*nb if side = 'L', and lwork >= m*nb if side = 'R', 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, and returns the value in work[0]. |
| [out] | info | = 0: Successful exit
= -1: The argument side had an illegal value. (side != 'L' nor 'R')
= -2: The argument trans had an illegal value. (trans != 'N' nor 'T')
= -3: The argument m had an illegal value (m < 0)
= -4: The argument n had an illegal value (n < 0)
= -5: The argument ilo had an illegal value (ilo < 1 or (ilo > m if side = 'L', ilo > n if side = 'R'))
= -6: The argument ihi had an illegal value ((ihi < min(ilo, m) or ihi > m if side = 'L'), (ihi < min(ilo, n) or ihi > n if side = 'R'))
= -7: The argument lda had an illegal value. (lda < max(1, m) if side = 'L', lda < max(1, n) if side = 'R')
= -10: The argument ldc had an illegal value. (ldc < max(1, m))
= -13: The argument lwork had an illegal value (lwork too small) |
- Reference
- LAPACK
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