# automatically apply Chop to outputs? [duplicate]

Is there a common trick to automatically show output with "Chop" applied? I typically get results like below, which hinders readability

{{1., -2.08167*10^-16, -1.73472*10^-18}, {-2.08167*10^-16, 1.,
3.19189*10^-16}, {-1.73472*10^-18, 3.19189*10^-16, 1.}}

• Run $Post = Chop; and try again. – J. M.'s discontentment Apr 5 '17 at 2:37 • $Post = # /. x_Real /; 0 < Abs[x] < 10^-10 :> SetAccuracy[x, -Log10@Abs[x]]& might be preferred sometimes. Since what should be zero is relative, this shows how big the number being treated as zero is. – Michael E2 Apr 5 '17 at 3:02
• The problem with $Post, imo, is that it is applied to every output. I don't think I'd want Chop applied to every output. Hence I don't use it, but apply formatters by hand & when appropriate. – Michael E2 Apr 5 '17 at 3:04 • Do you want your results to be chopped or do you want to show chopped results? – Kuba Apr 5 '17 at 7:15 • What Kuba is saying is that there is $Post, which affects what is stored in Out (i.e. the value of %) and there is $PrePrint, which only affects how it is shown on screen. I think $Post has a high potential for confusion because x=Sin[1], x+1 is going to be different from Sin[1], %+1. – Szabolcs Apr 5 '17 at 8:15