DQRT16 computes the residual for a solution of a system of linear


 equations  A*x = b  or  A'*x = b:


    RESID = norm(B - A*X) / ( max(m,n) * norm(A) * norm(X) * EPS ),


 where EPS is the machine epsilon.

TRANS

          TRANS is CHARACTER*1


          Specifies the form of the system of equations:


          = 'N':  A *x = b


          = 'T':  A'*x = b, where A' is the transpose of A


          = 'C':  A'*x = b, where A' is the transpose of A

M

          M is INTEGER


          The number of rows of the matrix A.  M >= 0.

N

          N is INTEGER


          The number of columns of the matrix A.  N >= 0.

NRHS

          NRHS is INTEGER


          The number of columns of B, the matrix of right hand sides.


          NRHS >= 0.

A

          A is DOUBLE PRECISION array, dimension (LDA,N)


          The original M x N matrix A.

LDA

          LDA is INTEGER


          The leading dimension of the array A.  LDA >= max(1,M).

X

          X is DOUBLE PRECISION array, dimension (LDX,NRHS)


          The computed solution vectors for the system of linear


          equations.

LDX

          LDX is INTEGER


          The leading dimension of the array X.  If TRANS = 'N',


          LDX >= max(1,N); if TRANS = 'T' or 'C', LDX >= max(1,M).

B

          B is DOUBLE PRECISION array, dimension (LDB,NRHS)


          On entry, the right hand side vectors for the system of


          linear equations.


          On exit, B is overwritten with the difference B - A*X.

LDB

          LDB is INTEGER


          The leading dimension of the array B.  IF TRANS = 'N',


          LDB >= max(1,M); if TRANS = 'T' or 'C', LDB >= max(1,N).

RWORK

          RWORK is DOUBLE PRECISION array, dimension (M)

RESID

          RESID is DOUBLE PRECISION


          The maximum over the number of right hand sides of


          norm(B - A*X) / ( max(m,n) * norm(A) * norm(X) * EPS ).

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