Condition number

A condition number is a number that tells us how sensitive something is. It is usually used to measure how sensitive a mathematical equation is to small changes in its input values. To understand the concept of condition number, imagine you have a balance scale. For each pair of weights, the scale will tell you the weights are equal, so the left and right sides of the scale balance. The condition number of the scale would tell us how sensitive the scale is—that is, how much change in the weights do we need to see a difference in the scale. If the condition number is low, we need very little difference between the weights in order to see the scale unbalance. If the condition number is high, then it would take larger differences between the weights for the scale to unbalance.