Computes the LU factorization of a general band matrix using the unblocked version of the algorithm.
The routine forms the
LUfactorization of a general real/complex
kusuper-diagonals. The routine uses partial pivoting with row interchanges and implements the unblocked version of the algorithm, calling Level 2 BLAS. See also
- INTEGER. The number of rows of the matrixA().m≥0
- INTEGER. The number of columns inA().n≥0
- INTEGER. The number of sub-diagonals within the band ofA().kl≥0
- INTEGER. The number of super-diagonals within the band ofA().ku≥0
- REALforsgbtf2DOUBLE PRECISIONfordgbtf2COMPLEXforcgbtf2DOUBLE COMPLEXforzgbtf2.Array,DIMENSION(ldab,*).The arrayabcontains the matrixAin band storage (see Matrix Arguments).The second dimension ofabmust be at leastmax(1,.n)
- INTEGER. The leading dimension of the arrayab.(ldab≥2kl+ku+1)
- Overwritten by details of the factorization. The diagonal andkl+kusuper-diagonals ofUare stored in the first 1 +kl+kurows ofab. The multipliers used during the factorization are stored in the nextklrows.
- INTEGER.Array,DIMENSIONat least max(1,min(m,n)).The pivot indices: rowiwas interchanged with rowipiv(i).
- INTEGER. If, the execution is successful.info=0If, theinfo=-ii-th parameter had an illegal value.If,info=iuis 0. The factorization has been completed, butiiUis exactly singular. Division by 0 will occur if you use the factorUfor solving a system of linear equations.