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* \brief Computes row and column scalings
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* -- SuperLU routine (version 2.0) --
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* Univ. of California Berkeley, Xerox Palo Alto Research Center,
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* and Lawrence Berkeley National Lab.
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* Modified from LAPACK routine SGEEQU
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* File name: sgsequ.c
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* History: Modified from LAPACK routine SGEEQU
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#include "slu_sdefs.h"
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* SGSEQU computes row and column scalings intended to equilibrate an
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* M-by-N sparse matrix A and reduce its condition number. R returns the row
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* scale factors and C the column scale factors, chosen to try to make
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* the largest element in each row and column of the matrix B with
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* elements B(i,j)=R(i)*A(i,j)*C(j) have absolute value 1.
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* R(i) and C(j) are restricted to be between SMLNUM = smallest safe
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* number and BIGNUM = largest safe number. Use of these scaling
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* factors is not guaranteed to reduce the condition number of A but
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* works well in practice.
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* See supermatrix.h for the definition of 'SuperMatrix' structure.
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* A (input) SuperMatrix*
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* The matrix of dimension (A->nrow, A->ncol) whose equilibration
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* factors are to be computed. The type of A can be:
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* Stype = SLU_NC; Dtype = SLU_S; Mtype = SLU_GE.
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* R (output) float*, size A->nrow
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* If INFO = 0 or INFO > M, R contains the row scale factors
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* C (output) float*, size A->ncol
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* If INFO = 0, C contains the column scale factors for A.
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* ROWCND (output) float*
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* If INFO = 0 or INFO > M, ROWCND contains the ratio of the
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* smallest R(i) to the largest R(i). If ROWCND >= 0.1 and
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* AMAX is neither too large nor too small, it is not worth
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* COLCND (output) float*
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* If INFO = 0, COLCND contains the ratio of the smallest
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* C(i) to the largest C(i). If COLCND >= 0.1, it is not
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* AMAX (output) float*
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* Absolute value of largest matrix element. If AMAX is very
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* close to overflow or very close to underflow, the matrix
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* = 0: successful exit
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* < 0: if INFO = -i, the i-th argument had an illegal value
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* > 0: if INFO = i, and i is
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* <= A->nrow: the i-th row of A is exactly zero
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* > A->ncol: the (i-M)-th column of A is exactly zero
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* =====================================================================
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sgsequ(SuperMatrix *A, float *r, float *c, float *rowcnd,
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float *colcnd, float *amax, int *info)
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SGSEQU computes row and column scalings intended to equilibrate an
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M-by-N sparse matrix A and reduce its condition number. R returns the row
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scale factors and C the column scale factors, chosen to try to make
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the largest element in each row and column of the matrix B with
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elements B(i,j)=R(i)*A(i,j)*C(j) have absolute value 1.
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R(i) and C(j) are restricted to be between SMLNUM = smallest safe
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number and BIGNUM = largest safe number. Use of these scaling
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factors is not guaranteed to reduce the condition number of A but
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works well in practice.
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See supermatrix.h for the definition of 'SuperMatrix' structure.
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A (input) SuperMatrix*
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The matrix of dimension (A->nrow, A->ncol) whose equilibration
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factors are to be computed. The type of A can be:
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Stype = SLU_NC; Dtype = SLU_S; Mtype = SLU_GE.
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R (output) float*, size A->nrow
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If INFO = 0 or INFO > M, R contains the row scale factors
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C (output) float*, size A->ncol
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If INFO = 0, C contains the column scale factors for A.
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ROWCND (output) float*
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If INFO = 0 or INFO > M, ROWCND contains the ratio of the
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smallest R(i) to the largest R(i). If ROWCND >= 0.1 and
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AMAX is neither too large nor too small, it is not worth
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COLCND (output) float*
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If INFO = 0, COLCND contains the ratio of the smallest
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C(i) to the largest C(i). If COLCND >= 0.1, it is not
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Absolute value of largest matrix element. If AMAX is very
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close to overflow or very close to underflow, the matrix
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< 0: if INFO = -i, the i-th argument had an illegal value
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> 0: if INFO = i, and i is
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<= A->nrow: the i-th row of A is exactly zero
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> A->ncol: the (i-M)-th column of A is exactly zero
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=====================================================================
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/* Local variables */
added
removed
scipy/sparse/linalg/dsolve/SuperLU/SRC/sgsequ.c
