dtpttf (l)  Linux Man Pages
dtpttf: copies a triangular matrix A from standard packed format (TP) to rectangular full packed format (TF)
NAME
DTPTTF  copies a triangular matrix A from standard packed format (TP) to rectangular full packed format (TF)SYNOPSIS
 SUBROUTINE DTPTTF(
 TRANSR, UPLO, N, AP, ARF, INFO )
 CHARACTER TRANSR, UPLO
 INTEGER INFO, N
 DOUBLE PRECISION AP( 0: * ), ARF( 0: * )
PURPOSE
DTPTTF copies a triangular matrix A from standard packed format (TP) to rectangular full packed format (TF).ARGUMENTS
 TRANSR (input) CHARACTER

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

= aqUaq: A is upper triangular;
= aqLaq: A is lower triangular.  N (input) INTEGER
 The order of the matrix A. N >= 0.
 AP (input) DOUBLE PRECISION array, dimension ( N*(N+1)/2 ),
 On entry, the upper or lower triangular matrix A, packed columnwise in a linear array. The jth column of A is stored in the array AP as follows: if UPLO = aqUaq, AP(i + (j1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = aqLaq, AP(i + (j1)*(2nj)/2) = A(i,j) for j<=i<=n.
 ARF (output) DOUBLE PRECISION array, dimension ( N*(N+1)/2 ),
 On exit, the upper or lower triangular matrix A stored in RFP format. For a further discussion see Notes below.
 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