### ML_DGECON – Estimates the reciprocal of the condition number of a general real matrix

Block SymbolLicensing group: MATRIX Function Description
The output references yA, yWORK and yIWORK are always set to the corresponding input references uA, uWORK and uIWORK. If HLD = on then nothing is computed otherwise the LAPACK function DGECON is called internally:

DGECON(sINORM, N, uA, LDA, anorm, rcond, uWORK, uIWORK, info);

where parameters of DGECON are set in the following way:

• If $\mathtt{\text{INORM}}=\mathtt{\text{on}}$ then the string sINORM is set to "I" else it is set to "1".
• N is number of columns of the matrix referenced by uA.
• LDA is the leading dimension of the matrix referenced by uA.
• rcond is returned reciprocal value of the condition number of the matrix referenced by uA.
• info is return code from the function DGECON.

The error flag E is set to on if:

• the reference uA or uWORK or uIWORK is not defined (i.e. input uA or uWORK or uIWORK is not connected),
• the matrix referenced by uA is not square,
• number of elements of the vector referenced by uWORK is less than $4\ast \mathtt{\text{N}}$,
• number of elements of the integer vector referenced by uIWORK is less than N,
• the call of the function DGECON returns error using the function XERBLA, see the return code info and system log.

See LAPACK documentation  for more details.

Inputs

 uA Input reference to matrix A Reference uWORK Input reference to working vector WORK Reference uIWORK Input reference to integer working vector WORK Reference INORM Use Infinity-norm Bool anorm Norm of the original matrix A  $\odot$0.0 Double (F64) HLD Hold Bool

Outputs

 yA Output reference to matrix A Reference yWORK Output reference to working vector WORK Reference yIWORK Output reference to integer working vector WORK Reference rcond The reciprocal of the condition number of the matrix A Double (F64) 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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