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Pack/unpack the upper or lower triangle of a symmetric matrix

**[Specification]**
**[Arguments]**
**[Method]**
**[References]**
**[Comments]**
**[Example]**
**Purpose**

To pack/unpack the upper or lower triangle of a symmetric matrix.
The packed matrix is stored column-wise in the one-dimensional
array AP.

**Specification**
SUBROUTINE MA02DD( JOB, UPLO, N, A, LDA, AP )
C .. Scalar Arguments ..
CHARACTER JOB, UPLO
INTEGER LDA, N
C .. Array Arguments ..
DOUBLE PRECISION A(LDA,*), AP(*)

**Arguments**
**Mode Parameters**

JOB CHARACTER*1
Specifies whether the matrix should be packed or unpacked,
as follows:
= 'P': The matrix should be packed;
= 'U': The matrix should be unpacked.
UPLO CHARACTER*1
Specifies the part of the matrix to be packed/unpacked,
as follows:
= 'U': Upper triangular part;
= 'L': Lower triangular part.

**Input/Output Parameters**
N (input) INTEGER
The order of the matrix A. N >= 0.
A (input or output) DOUBLE PRECISION array, dimension
(LDA,N)
This array is an input parameter if JOB = 'P', and an
output parameter if JOB = 'U'.
On entry, if JOB = 'P', the leading N-by-N upper
triangular part (if UPLO = 'U'), or lower triangular part
(if UPLO = 'L'), of this array must contain the
corresponding upper or lower triangle of the symmetric
matrix A, and the other strictly triangular part is not
referenced.
On exit, if JOB = 'U', the leading N-by-N upper triangular
part (if UPLO = 'U'), or lower triangular part (if
UPLO = 'L'), of this array contains the corresponding
upper or lower triangle of the symmetric matrix A; the
other strictly triangular part is not referenced.
LDA INTEGER
The leading dimension of the array A. LDA >= max(1,N).
AP (output or input) DOUBLE PRECISION array, dimension
(N*(N+1)/2)
This array is an output parameter if JOB = 'P', and an
input parameter if JOB = 'U'.
On entry, if JOB = 'U', the leading N*(N+1)/2 elements of
this array must contain the upper (if UPLO = 'U') or lower
(if UPLO = 'L') triangle of the symmetric matrix A, packed
column-wise. That is, the elements are stored in the order
11, 12, 22, ..., 1n, 2n, 3n, ..., nn, if UPLO = 'U';
11, 21, 31, ..., n1, 22, 32, ..., n2, ..., if UPLO = 'L'.
On exit, if JOB = 'P', the leading N*(N+1)/2 elements of
this array contain the upper (if UPLO = 'U') or lower
(if UPLO = 'L') triangle of the symmetric matrix A, packed
column-wise, as described above.

**Further Comments**
None

**Example**
**Program Text**

None

**Program Data**
None

**Program Results**
None

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