DGET51
Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
November 2006
November 2006
Purpose
DGET51 generally checks a decomposition of the form
A = U B V'
where ' means transpose and U and V are orthogonal.
Specifically, if ITYPE=1
RESULT = | A - U B V' | / ( |A| n ulp )
If ITYPE=2, then:
RESULT = | A - B | / ( |A| n ulp )
If ITYPE=3, then:
RESULT = | I - UU' | / ( n ulp )
A = U B V'
where ' means transpose and U and V are orthogonal.
Specifically, if ITYPE=1
RESULT = | A - U B V' | / ( |A| n ulp )
If ITYPE=2, then:
RESULT = | A - B | / ( |A| n ulp )
If ITYPE=3, then:
RESULT = | I - UU' | / ( n ulp )
Arguments
| ITYPE |
(input) INTEGER
Specifies the type of tests to be performed.
=1: RESULT = | A - U B V' | / ( |A| n ulp ) =2: RESULT = | A - B | / ( |A| n ulp ) =3: RESULT = | I - UU' | / ( n ulp ) |
| N |
(input) INTEGER
The size of the matrix. If it is zero, DGET51 does nothing.
It must be at least zero. |
| A |
(input) DOUBLE PRECISION array, dimension (LDA, N)
The original (unfactored) matrix.
|
| LDA |
(input) INTEGER
The leading dimension of A. It must be at least 1
and at least N. |
| B |
(input) DOUBLE PRECISION array, dimension (LDB, N)
The factored matrix.
|
| LDB |
(input) INTEGER
The leading dimension of B. It must be at least 1
and at least N. |
| U |
(input) DOUBLE PRECISION array, dimension (LDU, N)
The orthogonal matrix on the left-hand side in the
decomposition. Not referenced if ITYPE=2 |
| LDU |
(input) INTEGER
The leading dimension of U. LDU must be at least N and
at least 1. |
| V |
(input) DOUBLE PRECISION array, dimension (LDV, N)
The orthogonal matrix on the left-hand side in the
decomposition. Not referenced if ITYPE=2 |
| LDV |
(input) INTEGER
The leading dimension of V. LDV must be at least N and
at least 1. |
| WORK |
(workspace) DOUBLE PRECISION array, dimension (2*N**2)
|
| RESULT |
(output) DOUBLE PRECISION
The values computed by the test specified by ITYPE. The
value is currently limited to 1/ulp, to avoid overflow. Errors are flagged by RESULT=10/ulp. |