How do you chop a number to a specified number of significant digits, not round

Is there a way to chop a number in matlab? I dont want to round it, just chop it off after a number of significants.

like e = 2.71828 eRound=2.72 eChop=2.71

[KSSV]

x = exp(1) ;
iwant = str2num(sprintf('%0.2f\n',x)) ;

[Michael]

This rounds the input.

Answer 1

[Bruno Luong]

2 digits

fix(x*100)/100

[Stephen23]

+1 The simple, traditional way, which can also be used with round and ceil.

[Star Strider]

‘How do you chop a number to a specified number of significant digits, not round’

Note that by definition, fix rounds toward zero.

It does not truncate.

And that is the reason I did not use this approach.

[Stephen23]

"Note that by definition, fix rounds toward zero. It does not truncate."

What is the difference? Disregarding any possible floating-point effects, I do not see how these are different. According to Wikipedia these are the same: "round towards zero (or truncate, ..."

source: https://en.wikipedia.org/wiki/Rounding#Rounding_towards_zero

Indeed the standard definition of truncation is

source: https://en.wikipedia.org/wiki/Truncation

which is exactly what Bruno Luong's answer is doing.

I note that you highlighted the term "rounds" but did not define it: rounding does not only include rounding to integer and rounding half up, but is really a family of functions (which includes fix and floor and ceil). Without defining exactly which one you are referring to by "rounds", your critique is entirely lost on me...

[Bruno Luong]

I also fail to see why the fix method is criticized. I run this code, it does not look like I get different result than Star's solution

a = 1000*randn(1,1e6);
for x=a
    r1=fix(x*100)/100;
    s = sprintf('%.15f',x);
    i = find(s=='.');
    r2 = str2num(s(1:i+2)); 
    if r1~=r2
        keyboard
    end
end