DGEFA Class

***PURPOSE Factor a matrix using Gaussian elimination. ***CATEGORY D2A1 ***TYPE DOUBLE PRECISION (SGEFA-S, DGEFA-D, CGEFA-C) ***KEYWORDS GENERAL MATRIX, LINEAR ALGEBRA, LINPACK, MATRIX FACTORIZATION ***AUTHOR Moler, C. B., (U. of New Mexico) ***DESCRIPTION DGEFA factors a double precision matrix by Gaussian elimination. DGEFA is usually called by DGECO, but it can be called directly with a saving in time if RCOND is not needed. (Time for DGECO) = (1 + 9/N)*(Time for DGEFA) . On Entry A DOUBLE PRECISION(LDA, N) the matrix to be factored. LDA INTEGER the leading dimension of the array A . N INTEGER the order of the matrix A . On Return A an upper triangular matrix and the multipliers which were used to obtain it. The factorization can be written A = L*U where L is a product of permutation and unit lower triangular matrices and U is upper triangular. IPVT INTEGER(N) an integer vector of pivot indices. INFO INTEGER = 0 normal value. = K if U(K,K) .EQ. 0.0 . This is not an error condition for this subroutine, but it does indicate that DGESL or DGEDI will divide by zero if called. Use RCOND in DGECO for a reliable indication of singularity. ***REFERENCES J. J. Dongarra, J. R. Bunch, C. B. Moler, and G. W. Stewart, LINPACK Users' Guide, SIAM, 1979. ***ROUTINES CALLED DAXPY, DSCAL, IDAMAX ***REVISION HISTORY (YYMMDD) 780814 DATE WRITTEN 890831 Modified array declarations. (WRB) 890831 REVISION DATE from Version 3.2 891214 Prologue converted to Version 4.0 format. (BAB) 900326 Removed duplicate information from DESCRIPTION section. (WRB) 920501 Reformatted the REFERENCES section. (WRB) ***END PROLOGUE DGEFA

public class DGEFA

Public Class DGEFA