---
name: "sptsv.f"
section: "3"
platform: "linux"
package: "lapack-doc"
version: "3.12.1-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/sptsv.f"
---

# sptsv.f(3)

## NAME

SRC/sptsv.f

## SYNOPSIS

### Functions/Subroutines

subroutine **sptsv** (n, nrhs, d, e, b, ldb, info)\
  **SPTSV computes the solution to system of linear equations A \* X = B for PT matrices**

## Function/Subroutine Documentation

### subroutine sptsv (integer n, integer nrhs, real, dimension( \* ) d, real, dimension( \* ) e, real, dimension( ldb, \* ) b, integer ldb, integer info)

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

**Purpose:**

```
!>
!> SPTSV computes the solution to a real system of linear equations
!> A*X = B, where A is an N-by-N symmetric positive definite tridiagonal
!> matrix, and X and B are N-by-NRHS matrices.
!>
!> A is factored as A = L*D*L**T, 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**T.
!>
```

*E*

```
!>          E is REAL 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**T factorization of
!>          A.  (E can also be regarded as the superdiagonal of the unit
!>          bidiagonal factor U from the U**T*D*U factorization of A.)
!>
```

*B*

```
!>          B is REAL 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 principal minor of order i
!>                is not positive, 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.

Definition at line **113** of file **sptsv.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.