SGEDI(3)

SYNOPSIS
SUBROUTINE SGEDI (A, LDA, N, IPVT, DET, WORK, JOB)

NAME
sgedi - Compute the determinant and inverse of a matrix using the factors computed by SGECO or SGEFA.

LIBRARY
SLATEC (LINPACK)

CATEGORY
D2A1, D3A1

TYPE
SINGLE PRECISION (SGEDI-S, DGEDI-D, CGEDI-C)

KEYWORDS
DETERMINANT, INVERSE, LINEAR ALGEBRA, LINPACK, MATRIX

AUTHOR
Moler, C. B., (U. of New Mexico)

DESCRIPTION
SGEDI computes the determinant and inverse of a matrix using the factors computed by SGECO or SGEFA. On Entry A REAL(LDA, N) the output from SGECO or SGEFA. LDA INTEGER the leading dimension of the array A . N INTEGER the order of the matrix A . IPVT INTEGER(N) the pivot vector from SGECO or SGEFA. WORK REAL(N) work vector. Contents destroyed. JOB INTEGER = 11 both determinant and inverse. = 01 inverse only. = 10 determinant only. On Return A inverse of original matrix if requested. Otherwise unchanged. DET REAL(2) determinant of original matrix if requested. Otherwise not referenced. Determinant = DET(1) * 10.0**DET(2) with 1.0 .LE. ABS(DET(1)) .LT. 10.0 or DET(1) .EQ. 0.0 . Error Condition A division by zero will occur if the input factor contains a zero on the diagonal and the inverse is requested. It will not occur if the subroutines are called correctly and if SGECO has set RCOND .GT. 0.0 or SGEFA has set INFO .EQ. 0 .

REFERENCES
J. J. Dongarra, J. R. Bunch, C. B. Moler, and G. W. Stewart, LINPACK Users' Guide, SIAM, 1979.

ROUTINES CALLED
SAXPY, SSCAL, SSWAP

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)