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

# pzpttrf(3)

compute a Cholesky factorization of an N-by-N complex tridiagonal symmetric positive definite distributed matrix A(1:N, JA:JA+N-1)

## NAME

PZPTTRF - compute a Cholesky factorization of an N-by-N complex tridiagonal symmetric positive definite distributed matrix A(1:N, JA:JA+N-1)

## SYNOPSIS

- SUBROUTINE PZPTTRF(

  N, D, E, JA, DESCA, AF, LAF, WORK, LWORK, INFO )

- INTEGER

  INFO, JA, LAF, LWORK, N

- INTEGER

  DESCA( \* )

- COMPLEX\*16

  AF( \* ), E( \* ), WORK( \* )

- DOUBLE

  PRECISION D( \* )

## PURPOSE

PZPTTRF computes a Cholesky factorization of an N-by-N complex tridiagonal symmetric positive definite distributed matrix A(1:N, JA:JA+N-1). Reordering is used to increase parallelism in the factorization. This reordering results in factors that are DIFFERENT from those produced by equivalent sequential codes. These factors cannot be used directly by users; however, they can be used in\
 subsequent calls to PZPTTRS to solve linear systems.\

The factorization has the form\

        P A(1:N, JA:JA+N-1) P^T = U' D U  or\

        P A(1:N, JA:JA+N-1) P^T = L D L',\

where U is a tridiagonal upper triangular matrix and L is tridiagonal lower triangular, and P is a permutation matrix.\