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 $INORM = on$ 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 $4 * N$ ,
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 [7] 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 $⊙$ 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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