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

# pcpttrs(3)

solve a system of linear equations A(1:N, JA:JA+N-1) \* X = B(IB:IB+N-1, 1:NRHS)

## NAME

PCPTTRS - solve a system of linear equations   A(1:N, JA:JA+N-1) \* X = B(IB:IB+N-1, 1:NRHS)

## SYNOPSIS

- SUBROUTINE PCPTTRS(

  UPLO, N, NRHS, D, E, JA, DESCA, B, IB, DESCB, AF, LAF, WORK, LWORK, INFO )

- CHARACTER

  UPLO

- INTEGER

  IB, INFO, JA, LAF, LWORK, N, NRHS

- INTEGER

  DESCA( \* ), DESCB( \* )

- COMPLEX

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

- REAL

  D( \* )

## PURPOSE

PCPTTRS solves a system of linear equations

where A(1:N, JA:JA+N-1) is the matrix used to produce the factors stored in A(1:N,JA:JA+N-1) and AF by PCPTTRF.\
 A(1:N, JA:JA+N-1) is an N-by-N complex\
 tridiagonal symmetric positive definite distributed\
 matrix.\
 Depending on the value of UPLO, A stores either U or L in the equn A(1:N, JA:JA+N-1) = U'D \*U or L\*D L' as computed by PCPTTRF.

Routine PCPTTRF MUST be called first.\