*DECK SNBDI SUBROUTINE SNBDI (ABE, LDA, N, ML, MU, IPVT, DET) C***BEGIN PROLOGUE SNBDI C***PURPOSE Compute the determinant of a band matrix using the factors C computed by SNBCO or SNBFA. C***LIBRARY SLATEC C***CATEGORY D3A2 C***TYPE SINGLE PRECISION (SNBDI-S, DNBDI-D, CNBDI-C) C***KEYWORDS BANDED, DETERMINANT, LINEAR EQUATIONS, NONSYMMETRIC C***AUTHOR Voorhees, E. A., (LANL) C***DESCRIPTION C C SNBDI computes the determinant of a band matrix C using the factors computed by SNBCO or SNBFA. C If the inverse is needed, use SNBSL N times. C C On Entry C C ABE REAL(LDA, NC) C the output from SNBCO or SNBFA. C NC must be .GE. 2*ML+MU+1 . C C LDA INTEGER C the leading dimension of the array ABE . C C N INTEGER C the order of the original matrix. C C ML INTEGER C number of diagonals below the main diagonal. C C MU INTEGER C number of diagonals above the main diagonal. C C IPVT INTEGER(N) C the pivot vector from SNBCO or SNBFA. C C On Return C C DET REAL(2) C determinant of original matrix. C Determinant = DET(1) * 10.0**DET(2) C with 1.0 .LE. ABS(DET(1)) .LT. 10.0 C or DET(1) = 0.0 . C C***REFERENCES J. J. Dongarra, J. R. Bunch, C. B. Moler, and G. W. C Stewart, LINPACK Users' Guide, SIAM, 1979. C***ROUTINES CALLED (NONE) C***REVISION HISTORY (YYMMDD) C 800725 DATE WRITTEN C 890831 Modified array declarations. (WRB) C 890831 REVISION DATE from Version 3.2 C 891214 Prologue converted to Version 4.0 format. (BAB) C 920501 Reformatted the REFERENCES section. (WRB) C***END PROLOGUE SNBDI INTEGER LDA,N,ML,MU,IPVT(*) REAL ABE(LDA,*),DET(2) C REAL TEN INTEGER I C***FIRST EXECUTABLE STATEMENT SNBDI DET(1) = 1.0E0 DET(2) = 0.0E0 TEN = 10.0E0 DO 50 I = 1, N IF (IPVT(I) .NE. I) DET(1) = -DET(1) DET(1) = ABE(I,ML+1)*DET(1) IF (DET(1) .EQ. 0.0E0) GO TO 60 10 IF (ABS(DET(1)) .GE. 1.0E0) GO TO 20 DET(1) = TEN*DET(1) DET(2) = DET(2) - 1.0E0 GO TO 10 20 CONTINUE 30 IF (ABS(DET(1)) .LT. TEN) GO TO 40 DET(1) = DET(1)/TEN DET(2) = DET(2) + 1.0E0 GO TO 30 40 CONTINUE 50 CONTINUE 60 CONTINUE RETURN END