### Rank of float matrix

I want to compute the "numerical" rank of 9*18 FLOAT matrix A_float that i know is a good approximation of a REAL matrix A_real.

Is there any method to do that ?

More precisely, i want to know if A_real is of rank at most 8, so i compute all the minors of A_float which happen to be all less (in absolute value) than 10^-32, so i conclude that A_real has good chance to be of rank at most 8.

Is there is any method better than computing the 3 000 000 9*9 minors of A_float (which takes a few minutes) but i want to run this computation over a few thousand of differents A_float.