str2num() does not lose those extra digits. Instead, you are not displaying the full width of the number. At the MATLAB command line give the command format long g and try your code again.

You do not need to use |round|, as already has a precision option: >> num2str(pi,2) ans = '3.1' You could also use which converts a number to string and gives control over many format options, including the number of significant digits: >> sprintf('%.2g',pi) ans = '3.1' If you are trying to use this in a plot title, than using will not help you: |fprintf| prints text to a file or the command window. If you want the title of a plot then you need a string and the function, like this: >> str = num2str(pi,2) >> title(str)

Faster and more efficient than using |str2num| (which hides a slow |eval| call inside) is to simply use the low-level function : >> sscanf(strrep('57_77_','_','.'),'%f') ans = 57.770 This is ten times faster than the accepted answer (1e4 iterations): Elapsed time is 0.277028 seconds. % my code Elapsed time is 2.63426 seconds. % accepted answer

myString = 'YYYY MM DD hh mm .0200 .0325 .0375 .0425 .0475 .0525 .0575 .0625 .0675'; out=regexp(myString,'\d?\.?\d+','match')

Write:

num2str(1.2,'%07.2f')

the number befor the . is the total number of digits + the ..

So 7.2 means: 7 total characters, from them 2 are after the ..

Is the comma in the string meant to be a decimal point? E.g. s = '-0,01298784' s(s==',') = '.' str2double(s)

Ahh, yes, this is easily accomplished with MATLAB's num2str function, like so:

num2str(12.000 ,'%.3f')
num2str(4.0, '%.1f')
num2str(34.760000,'%.6f')

WRT " %x.f ", where x equals 3,1, and 6 in the examples above, this is called the formSpec, which I would encourage you to read about more, here. In this case, we are saying that the variable is a floating point number, and we want to preserve x digits after the decimal place. It is useful to know about format specification for parsing text, and to efficiently read from and write to files.

Edit: A point of clarification, and as I'm sure you already know, single quotes (' ') in MATLAB yield a character array rather than a string. These are different data types. If you're really after a string, just add string to the num2str argument, i.e.,

string(num2str(12.000 ,'%.3f'))
string(num2str(4.0, '%.1f'))
string(num2str(34.760000,'%.6f'))