---
name: "sdttrf"
section: "3"
platform: "linux"
package: "scalapack-doc"
version: "1.5-11"
release: "Debian 11 (Bullseye)"
platforms: ["linux"]
url: "https://new.carta.tech/sdttrf"
---

# sdttrf(3)

compute an LU factorization of a complex tridiagonal matrix A using elimination without partial pivoting

## NAME

SDTTRF - compute an LU factorization of a complex tridiagonal matrix A using elimination without partial pivoting

## SYNOPSIS

- SUBROUTINE SDTTRF(

  N, DL, D, DU, INFO )

- INTEGER

  INFO, N

- REAL

  D( \* ), DL( \* ), DU( \* )

## PURPOSE

SDTTRF computes an LU factorization of a complex tridiagonal matrix A using elimination without partial pivoting.

The factorization has the form\
\
    A = L \* U\
 where L is a product of unit lower bidiagonal\
 matrices and U is upper triangular with nonzeros in only the main diagonal and first superdiagonal.\

## ARGUMENTS

- N (input) INTEGER

  The order of the matrix A.  N \>= 0.

- DL (input/output) COMPLEX array, dimension (N-1)

  On entry, DL must contain the (n-1) subdiagonal elements of A. On exit, DL is overwritten by the (n-1) multipliers that define the matrix L from the LU factorization of A.

- D (input/output) COMPLEX array, dimension (N)

  On entry, D must contain the diagonal elements of A. On exit, D is overwritten by the n diagonal elements of the upper triangular matrix U from the LU factorization of A.

- DU (input/output) COMPLEX array, dimension (N-1)

  On entry, DU must contain the (n-1) superdiagonal elements of A. On exit, DU is overwritten by the (n-1) elements of the first superdiagonal of U.

- INFO (output) INTEGER

  \= 0:  successful exit\
   \< 0:  if INFO = -i, the i-th argument had an illegal value\
   \> 0:  if INFO = i, U(i,i) is exactly zero. The factorization has been completed, but the factor U is exactly singular, and division by zero will occur if it is used to solve a system of equations.