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ML_DGEBRD – Reduces a general real matrix to bidiagonal form by an orthogonal transformation

Block SymbolLicensing group: MATRIX
PIC

Function Description
The output references yA, yD, yE, yTAUQ, yTAUP and yWORK are always set to the corresponding input references uA, uD, uE, uTAUQ, uTAUP and uWORK. If HLD = on then nothing is computed otherwise the LAPACK function DGEBRD is called internally:

DGEBRD(M, N, uA, LDA, uD, uE, uTAUQ, uTAUP, uWORK, info);

where parameters of DGEBRD are set in the following way:

  • M is number of rows of the matrix referenced by uA.
  • N is number of columns of the matrix referenced by uA.
  • LDA is the leading dimension of the matrix referenced by uA.
  • info is return code from the function DGEBRD.

The error flag E is set to on if:

  • the reference uA or uD or uE or uTAUQ or uTAUP or uWORK is not defined (i.e. input uA or uD or uE or uTAUQ or uTAUP or uWORK is not connected),
  • number of elements of any vector referenced by uD, uTAUQ and uTAUP is less than MINMN, where MINMN is minimum from M and N,
  • number of elements of the vector referenced by uE is less than MINMN− 1,
  • the call of the function DGEBRD returns error using the function XERBLA, see the return code info and system log.

See LAPACK documentation [8] for more details.

Inputs

uA

Input reference to matrix A

Reference

uD

Diagonal elements of the bidiagonal matrix B

Reference

uE

Off-diagonal elements of the bidiagonal matrix B

Reference

uTAUQ

Reference to a vector of scalar factors of the elementary reflectors which represent the orthogonal matrix Q

Reference

uTAUP

Reference to a vector of scalar factors of the elementary reflectors which represent the orthogonal matrix P

Reference

uWORK

Input reference to working vector WORK

Reference

HLD

Hold

Bool

Outputs

yA

Output reference to matrix A

Reference

yD

Output reference to D

Reference

yE

Output reference to E

Reference

yTAUQ

Output reference to TAUQ

Reference

yTAUP

Output reference to TAUP

Reference

yWORK

Output reference to working vector WORK

Reference

E

Error indicator

Bool

info

LAPACK function result info. If info = -i, the i=th argument had an illegal value

Long (I32)

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