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LAPACK
3.5.0
LAPACK: Linear Algebra PACKage
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Go to the source code of this file.
Functions/Subroutines | |
subroutine | sptt02 (N, NRHS, D, E, X, LDX, B, LDB, RESID) |
SPTT02 More... | |
subroutine sptt02 | ( | integer | N, |
integer | NRHS, | ||
real, dimension( * ) | D, | ||
real, dimension( * ) | E, | ||
real, dimension( ldx, * ) | X, | ||
integer | LDX, | ||
real, dimension( ldb, * ) | B, | ||
integer | LDB, | ||
real | RESID | ||
) |
SPTT02
SPTT02 computes the residual for the solution to a symmetric tridiagonal system of equations: RESID = norm(B - A*X) / (norm(A) * norm(X) * EPS), where EPS is the machine epsilon.
[in] | N | N is INTEGTER The order of the matrix A. |
[in] | NRHS | NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrices B and X. NRHS >= 0. |
[in] | D | D is REAL array, dimension (N) The n diagonal elements of the tridiagonal matrix A. |
[in] | E | E is REAL array, dimension (N-1) The (n-1) subdiagonal elements of the tridiagonal matrix A. |
[in] | X | X is REAL array, dimension (LDX,NRHS) The n by nrhs matrix of solution vectors X. |
[in] | LDX | LDX is INTEGER The leading dimension of the array X. LDX >= max(1,N). |
[in,out] | B | B is REAL array, dimension (LDB,NRHS) On entry, the n by nrhs matrix of right hand side vectors B. On exit, B is overwritten with the difference B - A*X. |
[in] | LDB | LDB is INTEGER The leading dimension of the array B. LDB >= max(1,N). |
[out] | RESID | RESID is REAL norm(B - A*X) / (norm(A) * norm(X) * EPS) |
Definition at line 105 of file sptt02.f.