public class Sgbtf2
- 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.
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* SGBTF2 computes an LU factorization of a real m-by-n band matrix A
* using partial pivoting with row interchanges.
* This is the unblocked version of the algorithm, calling Level 2 BLAS.
* M (input) INTEGER
* The number of rows of the matrix A. M >= 0.
* N (input) INTEGER
* The number of columns of the matrix A. N >= 0.
* KL (input) INTEGER
* The number of subdiagonals within the band of A. KL >= 0.
* KU (input) INTEGER
* The number of superdiagonals within the band of A. KU >= 0.
* AB (input/output) REAL array, dimension (LDAB,N)
* On entry, the matrix A in band storage, in rows KL+1 to
* 2*KL+KU+1; rows 1 to KL of the array need not be set.
* The j-th column of A is stored in the j-th column of the
* array AB as follows:
* AB(kl+ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(m,j+kl)
* On exit, details of the factorization: U is stored as an
* upper triangular band matrix with KL+KU superdiagonals in
* rows 1 to KL+KU+1, and the multipliers used during the
* factorization are stored in rows KL+KU+2 to 2*KL+KU+1.
* See below for further details.
* LDAB (input) INTEGER
* The leading dimension of the array AB. LDAB >= 2*KL+KU+1.
* IPIV (output) INTEGER array, dimension (min(M,N))
* The pivot indices; for 1 <= i <= min(M,N), row i of the
* matrix was interchanged with row IPIV(i).
* INFO (output) INTEGER
* = 0: successful exit
* < 0: if INFO = -i, the i-th argument had an illegal value
* > 0: if INFO = +i, U(i,i) is exactly zero. The factorization
* has been completed, but the factor U is exactly
* singular, and division by zero will occur if it is used
* to solve a system of equations.
* Further Details
* The band storage scheme is illustrated by the following example, when
* M = N = 6, KL = 2, KU = 1:
* On entry: On exit:
* * * * + + + * * * u14 u25 u36
* * * + + + + * * u13 u24 u35 u46
* * a12 a23 a34 a45 a56 * u12 u23 u34 u45 u56
* a11 a22 a33 a44 a55 a66 u11 u22 u33 u44 u55 u66
* a21 a32 a43 a54 a65 * m21 m32 m43 m54 m65 *
* a31 a42 a53 a64 * * m31 m42 m53 m64 * *
* Array elements marked * are not used by the routine; elements marked
* + need not be set on entry, but are required by the routine to store
* elements of U, because of fill-in resulting from the row
* .. Parameters ..
|Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
public static void sgbtf2(int m,