mirror of
https://git.planet-casio.com/Lephenixnoir/OpenLibm.git
synced 2025-01-01 06:23:39 +01:00
86 lines
2.6 KiB
Fortran
86 lines
2.6 KiB
Fortran
*DECK CNBDI
|
|
SUBROUTINE CNBDI (ABE, LDA, N, ML, MU, IPVT, DET)
|
|
C***BEGIN PROLOGUE CNBDI
|
|
C***PURPOSE Compute the determinant of a band matrix using the factors
|
|
C computed by CNBCO or CNBFA.
|
|
C***LIBRARY SLATEC
|
|
C***CATEGORY D3C2
|
|
C***TYPE COMPLEX (SNBDI-S, DNBDI-D, CNBDI-C)
|
|
C***KEYWORDS BANDED, DETERMINANT, LINEAR EQUATIONS, NONSYMMETRIC
|
|
C***AUTHOR Voorhees, E. A., (LANL)
|
|
C***DESCRIPTION
|
|
C
|
|
C CNBDI computes the determinant of a band matrix
|
|
C using the factors computed by CNBCO or CNBFA.
|
|
C If the inverse is needed, use CNBSL N times.
|
|
C
|
|
C On Entry
|
|
C
|
|
C ABE COMPLEX(LDA, NC)
|
|
C the output from CNBCO or CNBFA.
|
|
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 CNBCO or CNBFA.
|
|
C
|
|
C On Return
|
|
C
|
|
C DET COMPLEX(2)
|
|
C determinant of original matrix.
|
|
C Determinant = DET(1) * 10.0**DET(2)
|
|
C with 1.0 .LE. CABS1(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 800730 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 CNBDI
|
|
INTEGER LDA,N,ML,MU,IPVT(*)
|
|
COMPLEX ABE(LDA,*),DET(2)
|
|
C
|
|
REAL TEN
|
|
INTEGER I
|
|
COMPLEX ZDUM
|
|
REAL CABS1
|
|
CABS1(ZDUM) = ABS(REAL(ZDUM)) + ABS(AIMAG(ZDUM))
|
|
C
|
|
C***FIRST EXECUTABLE STATEMENT CNBDI
|
|
DET(1) = (1.0E0,0.0E0)
|
|
DET(2) = (0.0E0,0.0E0)
|
|
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 (CABS1(DET(1)) .EQ. 0.0E0) GO TO 60
|
|
10 IF (CABS1(DET(1)) .GE. 1.0E0) GO TO 20
|
|
DET(1) = CMPLX(TEN,0.0E0)*DET(1)
|
|
DET(2) = DET(2) - (1.0E0,0.0E0)
|
|
GO TO 10
|
|
20 CONTINUE
|
|
30 IF (CABS1(DET(1)) .LT. TEN) GO TO 40
|
|
DET(1) = DET(1)/CMPLX(TEN,0.0E0)
|
|
DET(2) = DET(2) + (1.0E0,0.0E0)
|
|
GO TO 30
|
|
40 CONTINUE
|
|
50 CONTINUE
|
|
60 CONTINUE
|
|
RETURN
|
|
END
|