chop doesn't chop very small numbers

I have a small number, say 1e-14, and I want to chop it to three decimals. In this case, it should give 0. Yet:

>> chop(1e-14, 3)
ans =
   1.0000e-14

What is going on?

[James Tursa]

What is the function chop()?

[Star Strider]

The only reference I can find on an InterWeb search is the Wolfram function Chop—Wolfram Language Documentation (link).

I cannot find any documentation for a function of that exact name in MATLAB in a similar search.

[Alec Poulin]

That is weird, I cannot remember where I learned about this function. Anyway, on my computer, the file chop.m is located in /usr/local/MATLAB/R2018a/toolbox/control/ctrlobsolete. But then, I just saw that there is the word "obsolete" in the directory name...

Answer 1

[Steven Lord]

I believe chop is an old function from Control System Toolbox. I recommend using round instead. The default behavior of round is to round to N decimals but you can also use it to round to N significant digits (which is what chop(X, N) does.)

>> x = 1e-14;

>> round(x, 3)
ans =
     0

>> round(x, 3, 'significant')
ans =
   1.0000e-14