A matrix is ill-conditioned if the condition number is too large (and singular if it is infinite).
Ill-Conditioned Matrix
See also
Condition Number, Singular Matrix, Singular Value DecompositionExplore with Wolfram|Alpha
References
Arfken, G. "Ill-Conditioned Systems." Mathematical Methods for Physicists, 3rd ed. Orlando, FL: Academic Press, pp. 233-234, 1985.Referenced on Wolfram|Alpha
Ill-Conditioned MatrixCite this as:
Weisstein, Eric W. "Ill-Conditioned Matrix." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Ill-ConditionedMatrix.html