STPT02 computes the residual for the computed solution to a


 triangular system of linear equations op(A)*X = B, when the


 triangular matrix A is stored in packed format. The test ratio is


 the maximum over


    norm(b - op(A)*x) / ( ||op(A)||_1 * norm(x) * EPS ),


 where op(A) = A or A**T, b is the column of B, x is the solution


 vector, and EPS is the machine epsilon.


 The norm used is the 1-norm.

UPLO

          UPLO is CHARACTER*1


          Specifies whether the matrix A is upper or lower triangular.


          = 'U':  Upper triangular


          = 'L':  Lower triangular

TRANS

          TRANS is CHARACTER*1


          Specifies the operation applied to A.


          = 'N':  A    * X = B  (No transpose)


          = 'T':  A**T * X = B  (Transpose)


          = 'C':  A**H * X = B  (Conjugate transpose = Transpose)

DIAG

          DIAG is CHARACTER*1


          Specifies whether or not the matrix A is unit triangular.


          = 'N':  Non-unit triangular


          = 'U':  Unit triangular

N

          N is INTEGER


          The order of the matrix A.  N >= 0.

NRHS

          NRHS is INTEGER


          The number of right hand sides, i.e., the number of columns


          of the matrices X and B.  NRHS >= 0.

AP

          AP is REAL array, dimension (N*(N+1)/2)


          The upper or lower triangular matrix A, packed columnwise in


          a linear array.  The j-th column of A is stored in the array


          AP as follows:


          if UPLO = 'U', AP((j-1)*j/2 + i) = A(i,j) for 1<=i<=j;


          if UPLO = 'L',


             AP((j-1)*(n-j) + j*(j+1)/2 + i-j) = A(i,j) for j<=i<=n.

X

          X is REAL 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.  LDX >= max(1,N).

B

          B is REAL array, dimension (LDB,NRHS)


          The right hand side vectors for the system of linear


          equations.

LDB

          LDB is INTEGER


          The leading dimension of the array B.  LDB >= max(1,N).

WORK

          WORK is REAL array, dimension (N)

RESID

          RESID is REAL


          The maximum over the number of right hand sides of


          norm(op(A)*X - B) / ( norm(op(A)) * norm(X) * EPS ).

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