Description of geequ

geequ		Programmers Guide
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Category:mtl2lapack

Component type:function

Prototype

template <class LapackMatA, class VectorReal, class Real> int geequ(const LapackMatA& a, VectorReal& r, VectorReal& c, Real& row_cond, Real& col_cond, Real& amax) ;

Description

Compute row and column scaling inteded to equilibrate an M-by-N matrix A and reduce its condition number.

a (IN - matrix(M,N)) The M-by-N matrix whose equilibration factors are to be computed.
r (OUT - vector(M)) Real vector. If INFO = 0 or INFO > M, R contains the row scale factors for A.
c (OUT - vector(N)) Real vector. If INFO = 0, C contains the column scale factors for A.
row_cond (OUT - Real number) If INFO = 0 or INFO > M, ROWCND contains the ratio of the smallest R(i) to the largest R(i). If ROWCND >= 0.1 and AMAX is neither too large nor too small, it is not worth scaling by R.
col_cond (OUT - Real number) If INFO = 0, COLCND contains the ratio of the smallest C(i) to the largest C(i). If COLCND >= 0.1, it is not worth scaling by C.
amax (OUT - Real number) Absolute value of largest matrix element. If AMAX is very close to overflow or very close to underflow, the matrix should be scaled.

Definition

mtl2lapack.h

Preconditions

Complexity

Example

Notes

See also