CTRSV(3)

💖 CTRSV(3) — Library Functions Manual 💖

okay so bestie, this is the CTRSV(3) page from the Library Functions Manual, and it’s giving “complex triangular solve but make it iconic.” ✨ No cap, every deet is below. I’m lowkey obsessed with how much this routine ate and left no crumbs. 💅

🎀 NAME 🎀

The NAME is literally this source path — yes, the whole thing:

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/BLAS/SRC/ctrsv.f

🌸 SYNOPSIS 🌸

Functions/Subroutines:

subroutine CTRSV (uplo, trans, diag, n, a, lda, x, incx)
           CTRSV

🦋 Function/Subroutine Documentation 🦋

subroutine CTRSV (character uplo, character trans, character diag, integer
       n, complex, dimension(lda,*) a, integer lda, complex, dimension(*) x,
       integer incx)
       CTRSV

💅 Purpose 💅

okay so CTRSV solves one of these systems of equations:

A*x = b,   or   A**T*x = b,   or   A**H*x = b,

where b and x are n element vectors and A is an n by n unit, or non-unit, upper or lower triangular matrix. Slay.

⚠️ Important vibe check: no test for singularity or near-singularity is included in this routine. Such tests must be performed before calling this routine. Like, not me doing your background check for you — you gotta do that first, bestie. 💀

🍓 Parameters 🍓

🌈 UPLO

UPLO is CHARACTER*1. On entry, UPLO specifies whether the matrix is an upper or lower triangular matrix as follows:

• UPLO = 'U' or 'u' — A is an upper triangular matrix.
• UPLO = 'L' or 'l' — A is a lower triangular matrix.

🌈 TRANS

TRANS is CHARACTER*1. On entry, TRANS specifies the equations to be solved as follows:

• TRANS = 'N' or 'n' — A*x = b.
• TRANS = 'T' or 't' — A**T*x = b.
• TRANS = 'C' or 'c' — A**H*x = b.

🌈 DIAG

DIAG is CHARACTER*1. On entry, DIAG specifies whether or not A is unit triangular as follows:

• DIAG = 'U' or 'u' — A is assumed to be unit triangular.
• DIAG = 'N' or 'n' — A is not assumed to be unit triangular.

🌈 N

N is INTEGER. On entry, N specifies the order of the matrix A. N must be at least zero.

🌈 A

A is COMPLEX array, dimension ( LDA, N ). Before entry with UPLO = 'U' or 'u', the leading n by n upper triangular part of the array A must contain the upper triangular matrix and the strictly lower triangular part of A is not referenced. Before entry with UPLO = 'L' or 'l', the leading n by n lower triangular part of the array A must contain the lower triangular matrix and the strictly upper triangular part of A is not referenced. Note that when DIAG = 'U' or 'u', the diagonal elements of A are not referenced either, but are assumed to be unity.

🌈 LDA

LDA is INTEGER. On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. LDA must be at least max( 1, n ).

🌈 X

X is COMPLEX array, dimension at least ( 1 + ( n - 1 )*abs( INCX ) ). Before entry, the incremented array X must contain the n element right-hand side vector b. On exit, X is overwritten with the solution vector x.

🌈 INCX

INCX is INTEGER. On entry, INCX specifies the increment for the elements of X. INCX must not be zero.

👑 Author 👑

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

🔥 Further Details 🔥

Level 2 Blas routine.

• -- Written on 22-October-1986.
• Jack Dongarra, Argonne National Lab.
• Jeremy Du Croz, Nag Central Office.
• Sven Hammarling, Nag Central Office.
• Richard Hanson, Sandia National Labs.

Definition at line 148 of file ctrsv.f.

🧚 Author 🧚

Generated automatically by Doxygen for LAPACK from the source code.

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💖 Cute sign-off bestie: source/version is LAPACK Version 3.12.0, the footer path is /home/abui...SRC/ctrsv.f(3), and date-wise the only written-on date energy on this page is 22-October-1986 — so that’s what we’re serving. Periodt. 🎀