FreeMat
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Section: Array Generation and Manipulations
The 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.
Here is the reciprocal condition number for a random square matrix
--> A = rand(30); --> rcond(A) ans = 4.4279e-04
And here we calculate the same value using the definition of (reciprocal) condition number
--> 1/(norm(A,1)*norm(inv(A),1)) ans = 4.3595e-04
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.