LAPACK
3.5.0
LAPACK: Linear Algebra PACKage

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Functions/Subroutines  
subroutine  dgeequ (M, N, A, LDA, R, C, ROWCND, COLCND, AMAX, INFO) 
DGEEQU More...  
subroutine dgeequ  (  integer  M, 
integer  N,  
double precision, dimension( lda, * )  A,  
integer  LDA,  
double precision, dimension( * )  R,  
double precision, dimension( * )  C,  
double precision  ROWCND,  
double precision  COLCND,  
double precision  AMAX,  
integer  INFO  
) 
DGEEQU
Download DGEEQU + dependencies [TGZ] [ZIP] [TXT]DGEEQU computes row and column scalings intended to equilibrate an MbyN matrix A and reduce its condition number. R returns the row scale factors and C the column scale factors, chosen to try to make the largest element in each row and column of the matrix B with elements B(i,j)=R(i)*A(i,j)*C(j) have absolute value 1. R(i) and C(j) are restricted to be between SMLNUM = smallest safe number and BIGNUM = largest safe number. Use of these scaling factors is not guaranteed to reduce the condition number of A but works well in practice.
[in]  M  M is INTEGER The number of rows of the matrix A. M >= 0. 
[in]  N  N is INTEGER The number of columns of the matrix A. N >= 0. 
[in]  A  A is DOUBLE PRECISION array, dimension (LDA,N) The MbyN matrix whose equilibration factors are to be computed. 
[in]  LDA  LDA is INTEGER The leading dimension of the array A. LDA >= max(1,M). 
[out]  R  R is DOUBLE PRECISION array, dimension (M) If INFO = 0 or INFO > M, R contains the row scale factors for A. 
[out]  C  C is DOUBLE PRECISION array, dimension (N) If INFO = 0, C contains the column scale factors for A. 
[out]  ROWCND  ROWCND is DOUBLE PRECISION 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. 
[out]  COLCND  COLCND is DOUBLE PRECISION 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. 
[out]  AMAX  AMAX is DOUBLE PRECISION Absolute value of largest matrix element. If AMAX is very close to overflow or very close to underflow, the matrix should be scaled. 
[out]  INFO  INFO is INTEGER = 0: successful exit < 0: if INFO = i, the ith argument had an illegal value > 0: if INFO = i, and i is <= M: the ith row of A is exactly zero > M: the (iM)th column of A is exactly zero 
Definition at line 139 of file dgeequ.f.