Previous: strco Up: ../linpack.html Next: strsl
SUBROUTINE STRDI(T,LDT,N,DET,JOB,INFO)
INTEGER LDT,N,JOB,INFO
REAL T(LDT,1),DET(2)
C
C STRDI COMPUTES THE DETERMINANT AND INVERSE OF A REAL
C TRIANGULAR MATRIX.
C
C ON ENTRY
C
C T REAL(LDT,N)
C T CONTAINS THE TRIANGULAR MATRIX. THE ZERO
C ELEMENTS OF THE MATRIX ARE NOT REFERENCED, AND
C THE CORRESPONDING ELEMENTS OF THE ARRAY CAN BE
C USED TO STORE OTHER INFORMATION.
C
C LDT INTEGER
C LDT IS THE LEADING DIMENSION OF THE ARRAY T.
C
C N INTEGER
C N IS THE ORDER OF THE SYSTEM.
C
C JOB INTEGER
C = 010 NO DET, INVERSE OF LOWER TRIANGULAR.
C = 011 NO DET, INVERSE OF UPPER TRIANGULAR.
C = 100 DET, NO INVERSE.
C = 110 DET, INVERSE OF LOWER TRIANGULAR.
C = 111 DET, INVERSE OF UPPER TRIANGULAR.
C
C ON RETURN
C
C T INVERSE OF ORIGINAL MATRIX IF REQUESTED.
C OTHERWISE UNCHANGED.
C
C DET REAL(2)
C DETERMINANT OF ORIGINAL MATRIX IF REQUESTED.
C OTHERWISE NOT REFERENCED.
C DETERMINANT = DET(1) * 10.0**DET(2)
C WITH 1.0 .LE. ABS(DET(1)) .LT. 10.0
C OR DET(1) .EQ. 0.0 .
C
C INFO INTEGER
C INFO CONTAINS ZERO IF THE SYSTEM IS NONSINGULAR
C AND THE INVERSE IS REQUESTED.
C OTHERWISE INFO CONTAINS THE INDEX OF
C A ZERO DIAGONAL ELEMENT OF T.
C
C
C LINPACK. THIS VERSION DATED 08/14/78 .
C CLEVE MOLER, UNIVERSITY OF NEW MEXICO, ARGONNE NATIONAL LAB.
C
C SUBROUTINES AND FUNCTIONS
C
C BLAS SAXPY,SSCAL
C FORTRAN ABS,MOD
C