Estimates the Skeel condition number for a general banded matrix.
The function estimates the Skeel condition number of
A) * op2(
The Skeel condition number
A) = norminf(|inv(
is computed by computing scaling factors
is row equilibrated and by computing the standard infinity-norm condition number.
- CHARACTER*1. Must be'N'or'T'or'C'.Specifies the form of the system of equations:If, the system has the formtrans='N'A*X=B.If, the system has the formtrans='T'A*TX=B.If, the system has the formtrans='C'A*HX=B.
- INTEGER. The number of linear equations, that is, the order of the matrixA;n≥0.
- INTEGER. The number of subdiagonals within the band ofA;kl≥0.
- INTEGER. The number of superdiagonals within the band ofA;ku≥0.
- ab,afb, ,
- REALforsla_gbrcondDOUBLE PRECISIONfordla_gbrcondArrays:ab(ldab,*) contains the original band matrixAstored in rows from 1 tokl+ku+ 1. Thej-th column ofAis stored in thej-th column of the arrayabas follows:ab(ku+1+i-j,j) = A(i,j)formax(1,j-ku)≤i≤min(n,j+kl)afb(ldafb,*) contains details of the LU factorization of the band matrixA, as returned by?gbtrf.Uis stored as an upper triangular band matrix withsuperdiagonals in rows 1 tokl+ku, and the multipliers used during the factorization are stored in rowskl+ku+1tokl+ku+22*.kl+ku+1c,DIMENSION