Matrix reciprocal condition number estimate
c = rcond(A)
c = rcond(A) returns an estimate for the reciprocal of the condition of A in 1-norm. If A is well conditioned, rcond(A) is near 1.0. If A is badly conditioned, rcond(A) is near 0.0. Compared to cond, rcond is a more efficient, but less reliable, method of estimating the condition of a matrix.