SGET04
Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
November 2006
November 2006
Purpose
SGET04 computes the difference between a computed solution and the
true solution to a system of linear equations.
RESID = ( norm(X-XACT) * RCOND ) / ( norm(XACT) * EPS ),
where RCOND is the reciprocal of the condition number and EPS is the
machine epsilon.
true solution to a system of linear equations.
RESID = ( norm(X-XACT) * RCOND ) / ( norm(XACT) * EPS ),
where RCOND is the reciprocal of the condition number and EPS is the
machine epsilon.
Arguments
| N |
(input) INTEGER
The number of rows of the matrices X and XACT. N >= 0.
|
| NRHS |
(input) INTEGER
The number of columns of the matrices X and XACT. NRHS >= 0.
|
| X |
(input) REAL array, dimension (LDX,NRHS)
The computed solution vectors. Each vector is stored as a
column of the matrix X. |
| LDX |
(input) INTEGER
The leading dimension of the array X. LDX >= max(1,N).
|
| XACT |
(input) REAL array, dimension( LDX, NRHS )
The exact solution vectors. Each vector is stored as a
column of the matrix XACT. |
| LDXACT |
(input) INTEGER
The leading dimension of the array XACT. LDXACT >= max(1,N).
|
| RCOND |
(input) REAL
The reciprocal of the condition number of the coefficient
matrix in the system of equations. |
| RESID |
(output) REAL
The maximum over the NRHS solution vectors of
( norm(X-XACT) * RCOND ) / ( norm(XACT) * EPS ) |