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SPPSL

       SUBROUTINE SPPSL(AP,N,B)
       INTEGER N
       REAL AP(1),B(1)
 C
 C     SPPSL SOLVES THE REAL SYMMETRIC POSITIVE DEFINITE SYSTEM
 C     A * X = B
 C     USING THE FACTORS COMPUTED BY SPPCO OR SPPFA.
 C
 C     ON ENTRY
 C
 C        AP      REAL (N*(N+1)/2)
 C                THE OUTPUT FROM SPPCO OR SPPFA.
 C
 C        N       INTEGER
 C                THE ORDER OF THE MATRIX  A .
 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 SPPCO(AP,N,RCOND,Z,INFO)
 C           IF (RCOND IS TOO SMALL .OR. INFO .NE. 0) GO TO ...
 C           DO 10 J = 1, P
 C              CALL SPPSL(AP,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