ZLANGT(3)

💖 NAME 💖

hey bestie, welcome to the Library Functions Manual page for ZLANGT(3) 🫶 — the whole main-character file path is literally this:

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

---

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

okay so here’s the function signature, exactly as it’s vibing:

double precision function ZLANGT (norm, n, dl, d, du)

and what it does, no cap: ZLANGT returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of a general tridiagonal matrix. 💅

---

💅 Function/Subroutine Documentation 💅

here’s the full documentation with the big signature:

double precision function ZLANGT (character norm, integer n, complex*16, dimension( * ) dl, complex*16, dimension( * ) d, complex*16, dimension( * ) du)

ZLANGT returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of a general tridiagonal matrix. yes bestie, same energy as above, but now with the full parameter list 💖

🎯 Purpose 🎯

the purpose block is literally this:

!>
!> ZLANGT  returns the value of the one norm,  or the Frobenius norm, or
!> the  infinity norm,  or the  element of  largest absolute value  of a
!> complex tridiagonal matrix A.
!>

📦 Returns 📦

ZLANGT is the return value, and the piecewise definition is giving very much:

!>
!>    ZLANGT = ( max(abs(A(i,j))), NORM = 'M' or 'm'
!>             (
!>             ( norm1(A),         NORM = '1', 'O' or 'o'
!>             (
!>             ( normI(A),         NORM = 'I' or 'i'
!>             (
!>             ( normF(A),         NORM = 'F', 'f', 'E' or 'e'
!>
!> where  norm1  denotes the  one norm of a matrix (maximum column sum),
!> normI  denotes the  infinity norm  of a matrix  (maximum row sum) and
!> normF  denotes the  Frobenius norm of a matrix (square root of sum of
!> squares).  Note that  max(abs(A(i,j)))  is not a consistent matrix norm.
!>

tiny warning from the original, bestie: max(abs(A(i,j))) is not a consistent matrix norm. ⚠️

🧩 Parameters 🧩

🎀 NORM 🎀

!>          NORM is CHARACTER*1
!>          Specifies the value to be returned in ZLANGT as described
!>          above.
!>

🎀 N 🎀

!>          N is INTEGER
!>          The order of the matrix A.  N >= 0.  When N = 0, ZLANGT is
!>          set to zero.
!>

🎀 DL 🎀

!>          DL is COMPLEX*16 array, dimension (N-1)
!>          The (n-1) sub-diagonal elements of A.
!>

🎀 D 🎀

!>          D is COMPLEX*16 array, dimension (N)
!>          The diagonal elements of A.
!>

🎀 DU 🎀

!>          DU is COMPLEX*16 array, dimension (N-1)
!>          The (n-1) super-diagonal elements of A.
!>

✍️ Author ✍️

the iconique author lineup:

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

Definition at line 105 of file zlangt.f.

✍️ Author ✍️

okay and then there’s the auto-generated author bit:

Generated automatically by Doxygen for LAPACK from the source code.

---

xoxo, your LAPACK Version 3.12.0 bestie, reppin’ /home/abui...RC/zlangt.f(3) 💅✨ (that’s the footer source/version + path vibe; no separate date line in this footer, so I’m not inventing one 😌)