BLAS/SRC/dtpsv.f(3)

💅 BLAS/SRC/dtpsv.f(3) — Library Functions Manual ✨

Okay bestie, this is the dtpsv page, and it's giving packed triangular solver realness, fr fr. 🫶

🌸 NAME 🌸

BLAS/SRC/dtpsv.f

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

• subroutine dtpsv (uplo, trans, diag, n, ap, x, incx)
  • DTPSV

🦋 Function/Subroutine Documentation 🦋

subroutine dtpsv (character uplo, character trans, character diag, integer n, double precision, dimension(*) ap, double precision, dimension(*) x, integer incx)

DTPSV

🔥 Purpose 🔥

Okay so DTPSV solves one of these systems of equations:

A*x = b,   or   A**T*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, supplied in packed form.

⚠️ No test for singularity or near-singularity is included in this routine. Such tests must be performed before calling this routine. Do the vibe check before you call, bestie — this routine is not doing it for you. 💀

🎀 Parameters 🎀

• UPLO — is CHARACTER*1. On entry, UPLO specifies whether the matrix is an upper or lower triangular matrix, like this:
  • UPLO = 'U' or 'u' → A is an upper triangular matrix.
  • UPLO = 'L' or 'l' → A is a lower triangular matrix.
• TRANS — is CHARACTER*1. On entry, TRANS specifies the equations to be solved, like this:
  • TRANS = 'N' or 'n' → A*x = b.
  • TRANS = 'T' or 't' → A**T*x = b.
  • TRANS = 'C' or 'c' → A**T*x = b.
• DIAG — is CHARACTER*1. On entry, DIAG specifies whether or not A is unit triangular, like this:
  • DIAG = 'U' or 'u' → A is assumed to be unit triangular.
  • DIAG = 'N' or 'n' → A is not assumed to be unit triangular.
• N — is INTEGER. On entry, N specifies the order of the matrix A. N must be at least zero.
• AP — is DOUBLE PRECISION array, dimension at least ( ( n*( n + 1 ) )/2 ).
  • Before entry with UPLO = 'U' or 'u', the array AP must contain the upper triangular matrix packed sequentially, column by column, so that AP( 1 ) contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 1, 2 ) and a( 2, 2 ) respectively, and so on.
  • Before entry with UPLO = 'L' or 'l', the array AP must contain the lower triangular matrix packed sequentially, column by column, so that AP( 1 ) contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 2, 1 ) and a( 3, 1 ) respectively, and so on.
  • Note that when DIAG = 'U' or 'u', the diagonal elements of A are not referenced, but are assumed to be unity.
• X — is DOUBLE PRECISION 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 — 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 143 of file dtpsv.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

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💖 That's the whole page, bestie — LAPACK Version 3.12.0, page BLAS/SRC/dtpsv.f(3). The footer didn't give a date, so I'm not inventing one, periodt. 💅