How can I chop this expression?

Question

After some long calculations, Mathematica gives me this output:

$-0.11728 \, G_1^{\phantom{1}2} - 0.0692416\, G_1\, G_2 - 0.000011728 G_2^{\phantom{2}2}$

where G1 and G2 are two coefficients whose value I don't know, but I know that it must be integers and in the range (0; 10) (extremes excluded).

The last term is much smaller than the other two: how can I get rid of it? Chop doesn't work here since it only deals with numerical expressions.

Answer 1

If you want to apply Chop to just the numerical expressions you can use a Rule with a Condition that the subject is a number:

delta = 0.01;
rule = x_ :> Chop[x, delta] /; NumericQ[x]

exp = -1.2 G1^2 - 0.02 G1 G2 - 0.000011 G2^2;

exp /. rule

-1.2 G1^2 - 0.02 G1 G2

Answer 2

Chop accepts a second argument and appears to work only on numerical parts of an expression:

expr = -0.11728 G1^2 - 0.0692416 G1 G2 - 0.000011728 G2^2;

Chop[expr, 10^-3]

-0.11728 G1^2 - 0.0692416 G1 G2