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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