# cptsv.f - Man Page

## Synopsis

### Functions/Subroutines

subroutine **cptsv** (**N**, **NRHS**, D, E, B, **LDB**, INFO)

**CPTSV computes the solution to system of linear equations A * X = B for PT matrices**

## Function/Subroutine Documentation

### subroutine cptsv (integer N, integer NRHS, real, dimension( * ) D, complex, dimension( * ) E, complex, dimension( ldb, * ) B, integer LDB, integer INFO)

**CPTSV computes the solution to system of linear equations A * X = B for PT matrices**

**Purpose:**

CPTSV computes the solution to a complex system of linear equations A*X = B, where A is an N-by-N Hermitian positive definite tridiagonal matrix, and X and B are N-by-NRHS matrices. A is factored as A = L*D*L**H, and the factored form of A is then used to solve the system of equations.

**Parameters:***N*N is INTEGER The order of the matrix A. N >= 0.

*NRHS*NRHS is INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.

*D*D is REAL array, dimension (N) On entry, the n diagonal elements of the tridiagonal matrix A. On exit, the n diagonal elements of the diagonal matrix D from the factorization A = L*D*L**H.

*E*E is COMPLEX array, dimension (N-1) On entry, the (n-1) subdiagonal elements of the tridiagonal matrix A. On exit, the (n-1) subdiagonal elements of the unit bidiagonal factor L from the L*D*L**H factorization of A. E can also be regarded as the superdiagonal of the unit bidiagonal factor U from the U**H*D*U factorization of A.

*B*B is COMPLEX array, dimension (LDB,NRHS) On entry, the N-by-NRHS right hand side matrix B. On exit, if INFO = 0, the N-by-NRHS solution matrix X.

*LDB*LDB is INTEGER The leading dimension of the array B. LDB >= max(1,N).

*INFO*INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value > 0: if INFO = i, the leading minor of order i is not positive definite, and the solution has not been computed. The factorization has not been completed unless i = N.

**Author:**Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**December 2016

Definition at line 117 of file cptsv.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page cptsv(3) is an alias of cptsv.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK