CGECO - CGECO factors a complex matrix by Gaussian elimination and
estimates the condition of the matrix.
If RCOND is not needed, CGEFA is slightly faster. To solve A*X = B ,
follow CGECO By CGESL. To Compute INVERSE(A)*C , follow CGECO by CGESL.
To compute DETERMINANT(A) , follow CGECO by CGEDI. To compute
INVERSE(A) , follow CGECO by CGEDI.
A COMPLEX(LDA, N)
the matrix to be factored.
the leading dimension of the array A .
the order of the matrix A . On Return
A an upper triangular matrix and the multipliers
which were used to obtain it.
The factorization can be written A = L*U where
L is a product of permutation and unit lower
triangular matrices and U is upper triangular.
an integer vector of pivot indices.
an estimate of the reciprocal condition of A .
For the system A*X = B , relative perturbations
in A and B of size EPSILON may cause
relative perturbations in X of size EPSILON/RCOND .
If RCOND is so small that the logical expression
1.0 + RCOND .EQ. 1.0
is true, then A may be singular to working
precision. In particular, RCOND is zero if
exact singularity is detected or the estimate
a work vector whose contents are usually unimportant.
If A is close to a singular matrix, then Z is
an approximate null vector in the sense that
NORM(A*Z) = RCOND*NORM(A)*NORM(Z) . LINPACK. This version dated
08/14/78 . Cleve Moler, University of New Mexico, Argonne National Lab.
Subroutines and Functions LINPACK CGEFA BLAS CAXPY,CDOTC,CSSCAL,SCASUM
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