How to use str2double without rounding

Hi , I know this could be a possible duplicate but all those solutions stated there didn't work for me. I am using the str2double function and it always rounds the conversion to the 4 places after the decimal point. Do you guys have any idea on converting the whole string exactly the way it is without rounding ??

[Adam]

It doesn't do this for me at all.

>> str2double( '4.34576543' )

ans =

                  4.34576543

It seems to round to the 14th decimal place when I try it:

>> str2double( '4.34576543197566529101' )

ans =

            4.34576543197567

Answer 1

[Nut]

Hi,

maybe you need a proper set of the output display format:

https://it.mathworks.com/help/matlab/ref/format.html

The default format is "short", with the "long" format you can see more digits, look at the following example.

A = '0.219033048405430510873439814';
>> A

A =

0.219033048405430510873439814

>> str2double(A)

ans =

      0.2190

>> format long
>> str2double(A)

ans =

     0.219033048405431

Answer 2

[Stephen23]

str2double does not do any rounding: does its documentation mention "rounding" anywhere? In fact you are just getting confused by how numbers as displayed in MATLAB. How number values are displayed is a totally different thing to how they are stored in memory. str2double reads all of those digits correctly.

Use format to change how numbers are displayed:

>> format shortg
>> str2double('0.1234567890123456789')
ans =    0.12346
>> format longg
>> str2double('0.1234567890123456789')
ans =    0.123456789012346

There are plenty of format options: read the documentation and try some. Note that the double type is limited as to how many digits of precision it can handle. This is also not str2double's fault.