# dget51.f - Man Page

TESTING/EIG/dget51.f

## Synopsis

### Functions/Subroutines

subroutine dget51 (itype, n, a, lda, b, ldb, u, ldu, v, ldv, work, result)
DGET51

## Function/Subroutine Documentation

### subroutine dget51 (integer itype, integer n, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( ldb, * ) b, integer ldb, double precision, dimension( ldu, * ) u, integer ldu, double precision, dimension( ldv, * ) v, integer ldv, double precision, dimension( * ) work, double precision result)

DGET51

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 )```
Parameters

ITYPE

```          ITYPE is 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

```          N is INTEGER
The size of the matrix.  If it is zero, DGET51 does nothing.
It must be at least zero.```

A

```          A is DOUBLE PRECISION array, dimension (LDA, N)
The original (unfactored) matrix.```

LDA

```          LDA is INTEGER
The leading dimension of A.  It must be at least 1
and at least N.```

B

```          B is DOUBLE PRECISION array, dimension (LDB, N)
The factored matrix.```

LDB

```          LDB is INTEGER
The leading dimension of B.  It must be at least 1
and at least N.```

U

```          U is DOUBLE PRECISION array, dimension (LDU, N)
The orthogonal matrix on the left-hand side in the
decomposition.
Not referenced if ITYPE=2```

LDU

```          LDU is INTEGER
The leading dimension of U.  LDU must be at least N and
at least 1.```

V

```          V is DOUBLE PRECISION array, dimension (LDV, N)
The orthogonal matrix on the left-hand side in the
decomposition.
Not referenced if ITYPE=2```

LDV

```          LDV is INTEGER
The leading dimension of V.  LDV must be at least N and
at least 1.```

WORK

`          WORK is DOUBLE PRECISION array, dimension (2*N**2)`

RESULT

```          RESULT is 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.```
Author

Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Definition at line 147 of file dget51.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page dget51(3) is an alias of dget51.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK