truncate decimal numbers in matlab?

Question

Is there a quick and easy way to truncate a decimal number, say beyond 4 digits, in MATLAB?

round() isn't helping, it's still rounding off. I have to use it in for loop, so the quickest way is appreciated.

Thanks for your inputs.

Answer 1

Here's one method to truncate d digits after the decimal.

val = 1.234567;
d = 4;
val_trunc = fix(val*10^d)/10^d

Result

val_trunc =

   1.2345

If you know that val is positive then floor() will work in place of fix().

Answer 2

Yet another option:

x = -3.141592653;
x_trun = x - rem(x,0.0001)

x_trun =

    -3.1415

Kudos to gnovice for the update.

In general, for n decimal places:

x_trun = x - rem(x,10^-n)