# dbdt02.f - Man Page

TESTING/EIG/dbdt02.f

## Synopsis

### Functions/Subroutines

subroutine **dbdt02** (m, n, b, ldb, c, ldc, u, ldu, work, resid)**DBDT02**

## Function/Subroutine Documentation

### subroutine dbdt02 (integer m, integer n, double precision, dimension( ldb, * ) b, integer ldb, double precision, dimension( ldc, * ) c, integer ldc, double precision, dimension( ldu, * ) u, integer ldu, double precision, dimension( * ) work, double precision resid)

**DBDT02**

**Purpose:**

DBDT02 tests the change of basis C = U**H * B by computing the residual RESID = norm(B - U * C) / ( max(m,n) * norm(B) * EPS ), where B and C are M by N matrices, U is an M by M orthogonal matrix, and EPS is the machine precision.

**Parameters***M*M is INTEGER The number of rows of the matrices B and C and the order of the matrix Q.

*N*N is INTEGER The number of columns of the matrices B and C.

*B*B is DOUBLE PRECISION array, dimension (LDB,N) The m by n matrix B.

*LDB*LDB is INTEGER The leading dimension of the array B. LDB >= max(1,M).

*C*C is DOUBLE PRECISION array, dimension (LDC,N) The m by n matrix C, assumed to contain U**H * B.

*LDC*LDC is INTEGER The leading dimension of the array C. LDC >= max(1,M).

*U*U is DOUBLE PRECISION array, dimension (LDU,M) The m by m orthogonal matrix U.

*LDU*LDU is INTEGER The leading dimension of the array U. LDU >= max(1,M).

*WORK*WORK is DOUBLE PRECISION array, dimension (M)

*RESID*RESID is DOUBLE PRECISION RESID = norm(B - U * C) / ( max(m,n) * norm(B) * EPS ),

**Author**Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **111** of file **dbdt02.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page dbdt02(3) is an alias of dbdt02.f(3).

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