# spst01.f - Man Page

TESTING/LIN/spst01.f

## Synopsis

### Functions/Subroutines

subroutine **spst01** (uplo, n, a, lda, afac, ldafac, perm, ldperm, piv, rwork, resid, rank)**SPST01**

## Function/Subroutine Documentation

### subroutine spst01 (character uplo, integer n, real, dimension( lda, * ) a, integer lda, real, dimension( ldafac, * ) afac, integer ldafac, real, dimension( ldperm, * ) perm, integer ldperm, integer, dimension( * ) piv, real, dimension( * ) rwork, real resid, integer rank)

**SPST01**

**Purpose:**

SPST01 reconstructs a symmetric positive semidefinite matrix A from its L or U factors and the permutation matrix P and computes the residual norm( P*L*L'*P' - A ) / ( N * norm(A) * EPS ) or norm( P*U'*U*P' - A ) / ( N * norm(A) * EPS ), where EPS is the machine epsilon.

**Parameters***UPLO*UPLO is CHARACTER*1 Specifies whether the upper or lower triangular part of the symmetric matrix A is stored: = 'U': Upper triangular = 'L': Lower triangular

*N*N is INTEGER The number of rows and columns of the matrix A. N >= 0.

*A*A is REAL array, dimension (LDA,N) The original symmetric matrix A.

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

*AFAC*AFAC is REAL array, dimension (LDAFAC,N) The factor L or U from the L*L' or U'*U factorization of A.

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

*PERM*PERM is REAL array, dimension (LDPERM,N) Overwritten with the reconstructed matrix, and then with the difference P*L*L'*P' - A (or P*U'*U*P' - A)

*LDPERM*LDPERM is INTEGER The leading dimension of the array PERM. LDAPERM >= max(1,N).

*PIV*PIV is INTEGER array, dimension (N) PIV is such that the nonzero entries are P( PIV( K ), K ) = 1.

*RWORK*RWORK is REAL array, dimension (N)

*RESID*RESID is REAL If UPLO = 'L', norm(L*L' - A) / ( N * norm(A) * EPS ) If UPLO = 'U', norm(U'*U - A) / ( N * norm(A) * EPS )

*RANK*RANK is INTEGER number of nonzero singular values of A.

**Author**Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **132** of file **spst01.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page spst01(3) is an alias of spst01.f(3).

Tue Nov 28 2023 12:08:43 Version 3.12.0 LAPACK