Lorenz.......said it was the truncated numbers......which produced the butterfly effect..

When the Butterfly Effect Took Flight - MIT Technology Review

ttps://www.technologyreview.com/s/422809/when-the-butterfly-effect-took-flight/

Feb 22, 2011 - The idea came to be known as the “butterfly effect” after Lorenz suggested that the flap of a butterfly's wings might ultimately cause a tornado. And the butterfly effect, also known as “sensitive dependence on initial conditions,” has a profound corollary: forecasting the future can be nearly impossible.