STFTTP(3)

🎀 NAME 🎀

okay bestie, welcome to the Library Functions Manual — this page is stfttp.f(3), and the file it's repping is /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/stfttp.f. That's the whole name vibe. 💅

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✨ SYNOPSIS ✨

Functions/Subroutines

• subroutine STFTTP (transr, uplo, n, arf, ap, info) — STFTTP copies a triangular matrix from the rectangular full packed format (TF) to the standard packed format (TP).

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🦋 Function/Subroutine Documentation 🦋

Here's the full signature, bestie — do not lose a single character:

subroutine STFTTP (character transr, character uplo, integer n, real, dimension( 0: * ) arf, real, dimension( 0: * ) ap, integer info)

STFTTP copies a triangular matrix from the rectangular full packed format (TF) to the standard packed format (TP).

🌸 Purpose: 🌸

The source comments literally say:

!>
!> STFTTP copies a triangular matrix A from rectangular full packed
!> format (TF) to standard packed format (TP).
!>

So it's giving TF-to-TP glow-up, periodt. 🔥

🎀 Parameters 🎀

• TRANSR — this one is CHARACTER*1. 'N' means ARF is in Normal format; 'T' means ARF is in Transpose format. 👑
• UPLO — also CHARACTER*1. 'U' means A is upper triangular; 'L' means A is lower triangular. 💅
• N — INTEGER, the order of the matrix A. N >= 0. No negative orders, bestie. 🚫
• ARF — REAL array, dimension ( N*(N+1)/2 ). On entry, this is the upper or lower triangular matrix A stored in RFP format. For a further discussion see Notes below. 🦋
• AP — REAL array, dimension ( N*(N+1)/2 ). On exit, this is the upper or lower triangular matrix A, packed columnwise in a linear array. The j-th column of A is stored in the array AP as follows:

if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n.

• INFO — INTEGER. = 0: successful exit. < 0: if INFO = -i, the i-th argument had an illegal value. 😭

🫶 Author 🫶

• Univ. of Tennessee
• Univ. of California Berkeley
• Univ. of Colorado Denver
• NAG Ltd.

🔥 Further Details: 🔥

okay this is the part where it shows you the RFP format with actual grids. I'm not touching the diagrams because they are iconic; here's the exact source block:

!>
!>  We first consider Rectangular Full Packed (RFP) Format when N is
!>  even. We give an example where N = 6.
!>
!>      AP is Upper             AP is Lower
!>
!>   00 01 02 03 04 05       00
!>      11 12 13 14 15       10 11
!>         22 23 24 25       20 21 22
!>            33 34 35       30 31 32 33
!>               44 45       40 41 42 43 44
!>                  55       50 51 52 53 54 55
!>
!>
!>  Let TRANSR = 'N'. RFP holds AP as follows:
!>  For UPLO = 'U' 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 = 'L' 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 = 'N'.
!>
!>         RFP A                   RFP A
!>
!>        03 04 05                33 43 53
!>        13 14 15                00 44 54
!>        23 24 25                10 11 55
!>        33 34 35                20 21 22
!>        00 44 45                30 31 32
!>        01 11 55                40 41 42
!>        02 12 22                50 51 52
!>
!>  Now let TRANSR = 'T'. RFP A in both UPLO cases is just the
!>  transpose of RFP A above. One therefore gets:
!>
!>
!>           RFP A                   RFP A
!>
!>     03 13 23 33 00 01 02    33 00 10 20 30 40 50
!>     04 14 24 34 44 11 12    43 44 11 21 31 41 51
!>     05 15 25 35 45 55 22    53 54 55 22 32 42 52
!>
!>
!>  We then consider Rectangular Full Packed (RFP) Format when N is
!>  odd. We give an example where N = 5.
!>
!>     AP is Upper                 AP is Lower
!>
!>   00 01 02 03 04              00
!>      11 12 13 14              10 11
!>         22 23 24              20 21 22
!>            33 34              30 31 32 33
!>               44              40 41 42 43 44
!>
!>
!>  Let TRANSR = 'N'. RFP holds AP as follows:
!>  For UPLO = 'U' the upper trapezoid A(0:4,0:2) consists of the last
!>  three columns of AP upper. The lower triangle A(3:4,0:1) consists of
!>  the transpose of the first two columns of AP upper.
!>  For UPLO = 'L' the lower trapezoid A(0:4,0:2) consists of the first
!>  three columns of AP lower. The upper triangle A(0:1,1:2) consists of
!>  the transpose of the last two columns of AP lower.
!>  This covers the case N odd and TRANSR = 'N'.
!>
!>         RFP A                   RFP A
!>
!>        02 03 04                00 33 43
!>        12 13 14                10 11 44
!>        22 23 24                20 21 22
!>        00 33 34                30 31 32
!>        01 11 44                40 41 42
!>
!>  Now let TRANSR = 'T'. RFP A in both UPLO cases is just the
!>  transpose of RFP A above. One therefore gets:
!>
!>           RFP A                   RFP A
!>
!>     02 12 22 00 01             00 10 20 30 40 50
!>     03 13 23 33 11             33 11 21 31 41 51
!>     04 14 24 34 44             43 44 22 32 42 52
!>

Definition at line 186 of file stfttp.f.

💜 Author 💜

Generated automatically by Doxygen for LAPACK from the source code.

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sign-off, bestie: this page is from LAPACK Version 3.12.0, and the footer path is /home/abui...RC/stfttp.f(3). That's the source/version vibe — mwah. 💋