dtrttf (l)  Linux Manuals
dtrttf: copies a triangular matrix A from standard full format (TR) to rectangular full packed format (TF)
NAME
DTRTTF  copies a triangular matrix A from standard full format (TR) to rectangular full packed format (TF)SYNOPSIS
 SUBROUTINE DTRTTF(
 TRANSR, UPLO, N, A, LDA, ARF, INFO )
 CHARACTER TRANSR, UPLO
 INTEGER INFO, N, LDA
 DOUBLE PRECISION A( 0: LDA1, 0: * ), ARF( 0: * )
PURPOSE
DTRTTF copies a triangular matrix A from standard full format (TR) to rectangular full packed format (TF) .ARGUMENTS
 TRANSR (input) CHARACTER

= aqNaq: ARF in Normal form is wanted;
= aqTaq: ARF in Transpose form is wanted.  UPLO (input) CHARACTER

= aqUaq: Upper triangle of A is stored;
= aqLaq: Lower triangle of A is stored.  N (input) INTEGER
 The order of the matrix A. N >= 0.
 A (input) DOUBLE PRECISION array, dimension (LDA,N).
 On entry, the triangular matrix A. If UPLO = aqUaq, the leading NbyN upper triangular part of the array A contains the upper triangular matrix, and the strictly lower triangular part of A is not referenced. If UPLO = aqLaq, the leading NbyN lower triangular part of the array A contains the lower triangular matrix, and the strictly upper triangular part of A is not referenced.
 LDA (input) INTEGER
 The leading dimension of the matrix A. LDA >= max(1,N).
 ARF (output) DOUBLE PRECISION array, dimension (NT).
 NT=N*(N+1)/2. On exit, the triangular matrix A in RFP format.
 INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value
FURTHER DETAILS
We first consider Rectangular Full Packed (RFP) Format when N is even. We give an example where N = 6.Let TRANSR = aqNaq. RFP holds AP as follows:
For UPLO = aqUaq the upper trapezoid A(0:5,0:2) consists of the last three columns of AP upper. The lower triangle A(4:6,0:2) consists of the transpose of the first three columns of AP upper.
For UPLO = aqLaq the lower trapezoid A(1:6,0:2) consists of the first three columns of AP lower. The upper triangle A(0:2,0:2) consists of the transpose of the last three columns of AP lower.
This covers the case N even and TRANSR = aqNaq.
03 04 05
13 14 15
23 24 25
33 34 35
00 44 45
01 11 55
02 12 22
Now let TRANSR = aqTaq. RFP A in both UPLO cases is just the transpose of RFP A above. One therefore gets:
03 13 23 33 00 01 02
04 14 24 34 44 11 12
05 15 25 35 45 55 22
We first consider Rectangular Full Packed (RFP) Format when N is odd. We give an example where N = 5.
AP is Upper