num2str function does not work correctly if you change the default decimal separator and thousand separator in number format.
I mean;
if number is like this it works correctly: 2,450.35
if number is like this it does not work correctly: 2.450,35
for num2str function 2,450.35 is two thousands four hundred fifty dollars 35 penny
for num2str function 2.450,35 is two dollars 45 penny