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SUBROUTINE SPBSL(ABD,LDA,N,M,B) INTEGER LDA,N,M REAL ABD(LDA,1),B(1) C C SPBSL SOLVES THE REAL SYMMETRIC POSITIVE DEFINITE BAND C SYSTEM A*X = B C USING THE FACTORS COMPUTED BY SPBCO OR SPBFA. C C ON ENTRY C C ABD REAL(LDA, N) C THE OUTPUT FROM SPBCO OR SPBFA. C C LDA INTEGER C THE LEADING DIMENSION OF THE ARRAY ABD . C C N INTEGER C THE ORDER OF THE MATRIX A . C C M INTEGER C THE NUMBER OF DIAGONALS ABOVE THE MAIN DIAGONAL. C C B REAL(N) C THE RIGHT HAND SIDE VECTOR. C C ON RETURN C C B THE SOLUTION VECTOR X . C C ERROR CONDITION C C A DIVISION BY ZERO WILL OCCUR IF THE INPUT FACTOR CONTAINS C A ZERO ON THE DIAGONAL. TECHNICALLY THIS INDICATES C SINGULARITY BUT IT IS USUALLY CAUSED BY IMPROPER SUBROUTINE C ARGUMENTS. IT WILL NOT OCCUR IF THE SUBROUTINES ARE CALLED C CORRECTLY AND INFO .EQ. 0 . C C TO COMPUTE INVERSE(A) * C WHERE C IS A MATRIX C WITH P COLUMNS C CALL SPBCO(ABD,LDA,N,RCOND,Z,INFO) C IF (RCOND IS TOO SMALL .OR. INFO .NE. 0) GO TO ... C DO 10 J = 1, P C CALL SPBSL(ABD,LDA,N,C(1,J)) C 10 CONTINUE 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,SDOT C FORTRAN MIN0 C