org.netlib.lapack
Class Ssptrf
java.lang.Object
org.netlib.lapack.Ssptrf
public class Ssptrf
 extends java.lang.Object
Following is the description from the original
Fortran source. For each array argument, the Java
version will include an integer offset parameter, so
the arguments may not match the description exactly.
Contact seymour@cs.utk.edu with any questions.
* ..
*
* Purpose
* =======
*
* SSPTRF computes the factorization of a real symmetric matrix A stored
* in packed format using the BunchKaufman diagonal pivoting method:
*
* A = U*D*U**T or A = L*D*L**T
*
* where U (or L) is a product of permutation and unit upper (lower)
* triangular matrices, and D is symmetric and block diagonal with
* 1by1 and 2by2 diagonal blocks.
*
* Arguments
* =========
*
* UPLO (input) CHARACTER*1
* = 'U': Upper triangle of A is stored;
* = 'L': Lower triangle of A is stored.
*
* N (input) INTEGER
* The order of the matrix A. N >= 0.
*
* AP (input/output) REAL array, dimension (N*(N+1)/2)
* On entry, the upper or lower triangle of the symmetric matrix
* A, packed columnwise in a linear array. The jth column of A
* is stored in the array AP as follows:
* if UPLO = 'U', AP(i + (j1)*j/2) = A(i,j) for 1<=i<=j;
* if UPLO = 'L', AP(i + (j1)*(2nj)/2) = A(i,j) for j<=i<=n.
*
* On exit, the block diagonal matrix D and the multipliers used
* to obtain the factor U or L, stored as a packed triangular
* matrix overwriting A (see below for further details).
*
* IPIV (output) INTEGER array, dimension (N)
* Details of the interchanges and the block structure of D.
* If IPIV(k) > 0, then rows and columns k and IPIV(k) were
* interchanged and D(k,k) is a 1by1 diagonal block.
* If UPLO = 'U' and IPIV(k) = IPIV(k1) < 0, then rows and
* columns k1 and IPIV(k) were interchanged and D(k1:k,k1:k)
* is a 2by2 diagonal block. If UPLO = 'L' and IPIV(k) =
* IPIV(k+1) < 0, then rows and columns k+1 and IPIV(k) were
* interchanged and D(k:k+1,k:k+1) is a 2by2 diagonal block.
*
* INFO (output) INTEGER
* = 0: successful exit
* < 0: if INFO = i, the ith argument had an illegal value
* > 0: if INFO = i, D(i,i) is exactly zero. The factorization
* has been completed, but the block diagonal matrix D is
* exactly singular, and division by zero will occur if it
* is used to solve a system of equations.
*
* Further Details
* ===============
*
* 596  Based on modifications by J. Lewis, Boeing Computer Services
* Company
*
* If UPLO = 'U', then A = U*D*U', where
* U = P(n)*U(n)* ... *P(k)U(k)* ...,
* i.e., U is a product of terms P(k)*U(k), where k decreases from n to
* 1 in steps of 1 or 2, and D is a block diagonal matrix with 1by1
* and 2by2 diagonal blocks D(k). P(k) is a permutation matrix as
* defined by IPIV(k), and U(k) is a unit upper triangular matrix, such
* that if the diagonal block D(k) is of order s (s = 1 or 2), then
*
* ( I v 0 ) ks
* U(k) = ( 0 I 0 ) s
* ( 0 0 I ) nk
* ks s nk
*
* If s = 1, D(k) overwrites A(k,k), and v overwrites A(1:k1,k).
* If s = 2, the upper triangle of D(k) overwrites A(k1,k1), A(k1,k),
* and A(k,k), and v overwrites A(1:k2,k1:k).
*
* If UPLO = 'L', then A = L*D*L', where
* L = P(1)*L(1)* ... *P(k)*L(k)* ...,
* i.e., L is a product of terms P(k)*L(k), where k increases from 1 to
* n in steps of 1 or 2, and D is a block diagonal matrix with 1by1
* and 2by2 diagonal blocks D(k). P(k) is a permutation matrix as
* defined by IPIV(k), and L(k) is a unit lower triangular matrix, such
* that if the diagonal block D(k) is of order s (s = 1 or 2), then
*
* ( I 0 0 ) k1
* L(k) = ( 0 I 0 ) s
* ( 0 v I ) nks+1
* k1 s nks+1
*
* If s = 1, D(k) overwrites A(k,k), and v overwrites A(k+1:n,k).
* If s = 2, the lower triangle of D(k) overwrites A(k,k), A(k+1,k),
* and A(k+1,k+1), and v overwrites A(k+2:n,k:k+1).
*
* =====================================================================
*
* .. Parameters ..
Method Summary 
static void 
ssptrf(java.lang.String uplo,
int n,
float[] ap,
int _ap_offset,
int[] ipiv,
int _ipiv_offset,
intW info)

Methods inherited from class java.lang.Object 
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
Ssptrf
public Ssptrf()
ssptrf
public static void ssptrf(java.lang.String uplo,
int n,
float[] ap,
int _ap_offset,
int[] ipiv,
int _ipiv_offset,
intW info)