---
name: "zbdt02.f"
section: "3"
platform: "linux"
package: "lapack-doc"
version: "3.12.1-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/zbdt02.f"
---

# zbdt02.f(3)

## NAME

TESTING/EIG/zbdt02.f

## SYNOPSIS

### Functions/Subroutines

subroutine **zbdt02** (m, n, b, ldb, c, ldc, u, ldu, work, rwork, resid)\
 **ZBDT02**

## Function/Subroutine Documentation

### subroutine zbdt02 (integer m, integer n, complex\*16, dimension( ldb, \* ) b, integer ldb, complex\*16, dimension( ldc, \* ) c, integer ldc, complex\*16, dimension( ldu, \* ) u, integer ldu, complex\*16, dimension( \* ) work, double precision, dimension( \* ) rwork, double precision resid)

**ZBDT02**

**Purpose:**

```
!>
!> ZBDT02 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 COMPLEX*16 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 COMPLEX*16 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 COMPLEX*16 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 COMPLEX*16 array, dimension (M)
!>
```

*RWORK*

```
!>          RWORK 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 **118** of file **zbdt02.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.