Section: Array Generation and Manipulations
rcond
function is a FreeMat wrapper around LAPACKs
function XGECON
, which estimates the 1-norm condition
number (reciprocal). For the details of the algorithm see
the LAPACK documentation. The syntax for its use is
x = rcond(A)
where A
is a matrix.
--> A = rand(30); --> rcond(A) ans = 6.6318e-04 --> quit
And here we calculate the same value using the definition of (reciprocal) condition number
--> 1/(norm(A,1)*norm(inv(A),1)) ans = 6.5055e-04 --> quit
Note that the values are very similar. LAPACKs rcond
function is far more efficient than the explicit calculation
(which is also used by the cond
function.